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</svg></div><div class="menu-modal"><a aria-hidden="true" class="leve2 tocs-link" data-num="2" href="#入门">入门</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#hellocpp">hello.cpp</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#变量">变量</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#原始数据类型">原始数据类型</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#用户输入">用户输入</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#交换">交换</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#注释">注释</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#if-语句">If 语句</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#循环">循环</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#函数">函数</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#引用">引用</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#命名空间">命名空间</a><a 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href="#several-variations">Several variations</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#auto">auto</a><a aria-hidden="true" class="leve2 tocs-link" data-num="2" href="#c-函数">C++ 函数</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#参数和返回">参数和返回</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#重载">重载</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#内置函数">内置函数</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#lambda-表达式">Lambda 表达式</a><a aria-hidden="true" class="leve2 tocs-link" data-num="2" href="#c智能指针">C++智能指针</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#智能指针基础">智能指针基础</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#unique_ptr">unique_ptr</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#shared_ptr">shared_ptr</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#weak_ptr">weak_ptr</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#循环引用问题">循环引用问题</a><a aria-hidden="true" class="leve2 tocs-link" data-num="2" href="#c多线程">C++多线程</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#多线程介绍">多线程介绍</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#线程的创建">线程的创建</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#线程的销毁">线程的销毁</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#this_thread">this_thread</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#锁">锁</a><a aria-hidden="true" class="leve4 tocs-link" data-num="4" href="#锁的基本操作">锁的基本操作</a><a aria-hidden="true" class="leve4 tocs-link" data-num="4" href="#更简单的锁--stdlock_guardmutex">更简单的锁 —— std::lock_guard<Mutex></a><a aria-hidden="true" class="leve4 tocs-link" data-num="4" href="#unique_lockmutex">unique_lock<Mutex></a><a aria-hidden="true" class="leve5 tocs-link" data-num="5" href="#stdadopt_lock">std::adopt_lock</a><a aria-hidden="true" class="leve5 tocs-link" data-num="5" href="#stdtry_to_lock">std::try_to_lock</a><a aria-hidden="true" class="leve5 tocs-link" data-num="5" href="#stddefer_lock">std::defer_lock</a><a aria-hidden="true" class="leve5 tocs-link" data-num="5" href="#stdunique_lockmutexrelease">std::unique_lock<Mutex>::release</a><a aria-hidden="true" class="leve4 tocs-link" data-num="4" href="#stdcall_once">std::call_once</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#stdcondition_variable">std::condition_variable</a><a aria-hidden="true" class="leve4 tocs-link" data-num="4" href="#创建条件变量">创建条件变量</a><a aria-hidden="true" class="leve4 tocs-link" data-num="4" href="#等待条件变量被通知">等待条件变量被通知</a><a aria-hidden="true" class="leve4 tocs-link" data-num="4" href="#stdcondition_variablenotify_one">std::condition_variable::notify_one</a><a aria-hidden="true" class="leve4 tocs-link" data-num="4" href="#stdcondition_variablenotify_all">std::condition_variable::notify_all</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#获取线程的运行结果">获取线程的运行结果</a><a aria-hidden="true" class="leve4 tocs-link" data-num="4" href="#创建异步任务">创建异步任务</a><a aria-hidden="true" class="leve4 tocs-link" data-num="4" href="#获取异步任务的返回值">获取异步任务的返回值</a><a aria-hidden="true" class="leve4 tocs-link" data-num="4" href="#stdasync-的额外参数">std::async 的额外参数</a><a aria-hidden="true" class="leve4 tocs-link" data-num="4" href="#返回值的状态">返回值的状态</a><a aria-hidden="true" class="leve4 tocs-link" data-num="4" href="#多个返回值">多个返回值</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#创建线程">创建线程</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#传递参数给线程函数">传递参数给线程函数</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#使用lambda表达式创建线程">使用Lambda表达式创建线程</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#处理线程间的同步">处理线程间的同步：</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#使用stdasync启动异步任务">使用std::async启动异步任务：</a><a aria-hidden="true" class="leve2 tocs-link" data-num="2" href="#c-预处理器">C++ 预处理器</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#预处理器">预处理器</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#includes">Includes</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#defines">Defines</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#if">If</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#error">Error</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#宏">宏</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#令牌连接">令牌连接</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#字符串化">字符串化</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#文件和行">文件和行</a><a aria-hidden="true" class="leve2 tocs-link" data-num="2" href="#各种各样的">各种各样的</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#转义序列">转义序列</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#关键字">关键字</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#预处理器-1">预处理器</a><a aria-hidden="true" class="leve2 tocs-link" data-num="2" href="#另见">另见</a></div></div><div class="h1wrap-body"><div class="wrap h2body-exist"><div class="wrap-header h2wrap"><h2 id="入门"><a aria-hidden="true" tabindex="-1" href="#入门"><span class="icon icon-link"></span></a>入门</h2><div class="wrap-body">
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</div></div><div class="h2wrap-body"><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="hellocpp"><a aria-hidden="true" tabindex="-1" href="#hellocpp"><span class="icon icon-link"></span></a>hello.cpp</h3><div class="wrap-body">
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||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span> <span class="token string"><iostream></span></span>
|
||
</span><span class="code-line"><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"Hello Quick Reference\n"</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> <span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span></code></pre>
|
||
<p>编译运行</p>
|
||
<pre class="language-shell"><code class="language-shell code-highlight"><span class="code-line">$ g++ hello.cpp <span class="token parameter variable">-o</span> hello
|
||
</span><span class="code-line">$ ./hello
|
||
</span><span class="code-line">Hello Quick Reference
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="变量"><a aria-hidden="true" tabindex="-1" href="#变量"><span class="icon icon-link"></span></a>变量</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">int</span> number <span class="token operator">=</span> <span class="token number">5</span><span class="token punctuation">;</span> <span class="token comment">// 整数</span>
|
||
</span><span class="code-line"><span class="token keyword">float</span> f <span class="token operator">=</span> <span class="token number">0.95</span><span class="token punctuation">;</span> <span class="token comment">// 浮点数</span>
|
||
</span><span class="code-line"><span class="token keyword">double</span> PI <span class="token operator">=</span> <span class="token number">3.14159</span><span class="token punctuation">;</span> <span class="token comment">// 浮点数</span>
|
||
</span><span class="code-line"><span class="token keyword">char</span> yes <span class="token operator">=</span> <span class="token char">'Y'</span><span class="token punctuation">;</span> <span class="token comment">// 字符</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>string s <span class="token operator">=</span> <span class="token string">"ME"</span><span class="token punctuation">;</span> <span class="token comment">// 字符串（文本）</span>
|
||
</span><span class="code-line"><span class="token keyword">bool</span> isRight <span class="token operator">=</span> <span class="token boolean">true</span><span class="token punctuation">;</span> <span class="token comment">// 布尔值</span>
|
||
</span><span class="code-line"><span class="token comment">// 常量</span>
|
||
</span><span class="code-line"><span class="token keyword">const</span> <span class="token keyword">float</span> RATE <span class="token operator">=</span> <span class="token number">0.8</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
<hr>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">int</span> age <span class="token punctuation">{</span><span class="token number">25</span><span class="token punctuation">}</span><span class="token punctuation">;</span> <span class="token comment">// 自 C++11</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> age<span class="token punctuation">;</span> <span class="token comment">// 打印 25</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="原始数据类型"><a aria-hidden="true" tabindex="-1" href="#原始数据类型"><span class="icon icon-link"></span></a>原始数据类型</h3><div class="wrap-body">
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
<table class="show-header"><thead><tr><th align="left">数据类型</th><th>大小</th><th>范围</th></tr></thead><tbody><tr><td align="left"><code>int</code></td><td>4 bytes</td><td>-2<sup>31</sup> 到 2<sup>31</sup>-1</td></tr><tr><td align="left"><code>float</code></td><td>4 bytes</td><td><em>N/A</em></td></tr><tr><td align="left"><code>double</code></td><td>8 bytes</td><td><em>N/A</em></td></tr><tr><td align="left"><code>char</code></td><td>1 byte</td><td>-128 到 127</td></tr><tr><td align="left"><code>bool</code></td><td>1 byte</td><td><code>true</code> / <code>false</code></td></tr><tr><td align="left"><code>void</code></td><td><em>N/A</em></td><td><em>N/A</em></td></tr><tr><td align="left"><code>wchar_t</code></td><td>2 到 4 bytes</td><td>1 个宽字符</td></tr></tbody></table>
|
||
<!--rehype:className=show-header-->
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="用户输入"><a aria-hidden="true" tabindex="-1" href="#用户输入"><span class="icon icon-link"></span></a>用户输入</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">int</span> num<span class="token punctuation">;</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"Type a number: "</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>cin <span class="token operator">>></span> num<span class="token punctuation">;</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"You entered "</span> <span class="token operator"><<</span> num<span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="交换"><a aria-hidden="true" tabindex="-1" href="#交换"><span class="icon icon-link"></span></a>交换</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">int</span> a <span class="token operator">=</span> <span class="token number">5</span><span class="token punctuation">,</span> b <span class="token operator">=</span> <span class="token number">10</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span><span class="token function">swap</span><span class="token punctuation">(</span>a<span class="token punctuation">,</span> b<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token comment">// 输出: a=10, b=5</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"a="</span> <span class="token operator"><<</span> a <span class="token operator"><<</span> <span class="token string">", b="</span> <span class="token operator"><<</span> b<span class="token punctuation">;</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment">// 整数交换的奇技淫巧</span>
|
||
</span><span class="code-line"><span class="token punctuation">(</span>x <span class="token operator">^=</span> y<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span>y <span class="token operator">^=</span> x<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span>x <span class="token operator">^=</span> y<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token comment">// 注意！ 以下操作会造成 undefined behavior</span>
|
||
</span><span class="code-line">x <span class="token operator">^=</span> y <span class="token operator">^=</span> x <span class="token operator">^=</span> y<span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="注释"><a aria-hidden="true" tabindex="-1" href="#注释"><span class="icon icon-link"></span></a>注释</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token comment">// C++中的单行注释</span>
|
||
</span><span class="code-line"><span class="token comment">/* 这是一个多行注释
|
||
</span></span><span class="code-line"><span class="token comment"> 在 C++ 中 */</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="if-语句"><a aria-hidden="true" tabindex="-1" href="#if-语句"><span class="icon icon-link"></span></a>If 语句</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">if</span> <span class="token punctuation">(</span>a <span class="token operator">==</span> <span class="token number">10</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token comment">// do something</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span></code></pre>
|
||
<p>查看: <a href="#c-%E6%9D%A1%E4%BB%B6">条件</a></p>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="循环"><a aria-hidden="true" tabindex="-1" href="#循环"><span class="icon icon-link"></span></a>循环</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">int</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> i <span class="token operator"><</span> <span class="token number">10</span><span class="token punctuation">;</span> i<span class="token operator">++</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> i <span class="token operator"><<</span> <span class="token string">"\n"</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span></code></pre>
|
||
<p>查看: <a href="#c-%E5%BE%AA%E7%8E%AF">循环 Loops</a></p>
|
||
</div></div></div><div class="wrap h3body-not-exist row-span-2"><div class="wrap-header h3wrap"><h3 id="函数"><a aria-hidden="true" tabindex="-1" href="#函数"><span class="icon icon-link"></span></a>函数</h3><div class="wrap-body">
|
||
<!--rehype:wrap-class=row-span-2-->
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span> <span class="token string"><iostream></span></span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token keyword">void</span> <span class="token function">hello</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 声明</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> <span class="token comment">// 主函数</span>
|
||
</span><span class="code-line"> <span class="token function">hello</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 执行函数</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token keyword">void</span> <span class="token function">hello</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> <span class="token comment">// 定义</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"Hello Quick Reference!\n"</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span></code></pre>
|
||
<p>查看: <a href="#c-%E5%87%BD%E6%95%B0">函数 Functions</a></p>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="引用"><a aria-hidden="true" tabindex="-1" href="#引用"><span class="icon icon-link"></span></a>引用</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">int</span> i <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token keyword">int</span><span class="token operator">&</span> ri <span class="token operator">=</span> i<span class="token punctuation">;</span> <span class="token comment">// ri 是对 i 的引用</span>
|
||
</span><span class="code-line">ri <span class="token operator">=</span> <span class="token number">2</span><span class="token punctuation">;</span> <span class="token comment">// i 现在改为 2</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"i="</span> <span class="token operator"><<</span> i<span class="token punctuation">;</span>
|
||
</span><span class="code-line">i <span class="token operator">=</span> <span class="token number">3</span><span class="token punctuation">;</span> <span class="token comment">// i 现在改为 3</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"ri="</span> <span class="token operator"><<</span> ri<span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
<p><code>ri</code> 和 <code>i</code> 指的是相同的内存位置</p>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="命名空间"><a aria-hidden="true" tabindex="-1" href="#命名空间"><span class="icon icon-link"></span></a>命名空间</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span> <span class="token string"><iostream></span></span>
|
||
</span><span class="code-line"><span class="token keyword">namespace</span> ns1 <span class="token punctuation">{</span><span class="token keyword">int</span> <span class="token function">val</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">return</span> <span class="token number">5</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||
</span><span class="code-line"><span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> ns1<span class="token double-colon punctuation">::</span><span class="token function">val</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span></code></pre>
|
||
<hr>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span> <span class="token string"><iostream></span></span>
|
||
</span><span class="code-line"><span class="token keyword">namespace</span> ns1 <span class="token punctuation">{</span><span class="token keyword">int</span> <span class="token function">val</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">return</span> <span class="token number">5</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token keyword">using</span> <span class="token keyword">namespace</span> ns1<span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token keyword">using</span> <span class="token keyword">namespace</span> std<span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||
</span><span class="code-line"><span class="token punctuation">{</span>
|
||
</span><span class="code-line"> cout <span class="token operator"><<</span> <span class="token function">val</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span></code></pre>
|
||
<p>名称空间允许名称下的全局标识符</p>
|
||
</div></div></div></div></div><div class="wrap h2body-exist"><div class="wrap-header h2wrap"><h2 id="c-数组"><a aria-hidden="true" tabindex="-1" href="#c-数组"><span class="icon icon-link"></span></a>C++ 数组</h2><div class="wrap-body">
|
||
</div></div><div class="h2wrap-body"><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="定义"><a aria-hidden="true" tabindex="-1" href="#定义"><span class="icon icon-link"></span></a>定义</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line">std<span class="token double-colon punctuation">::</span>array<span class="token operator"><</span><span class="token keyword">int</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token operator">></span> marks<span class="token punctuation">;</span> <span class="token comment">// 定义</span>
|
||
</span><span class="code-line">marks<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token number">92</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">marks<span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token number">97</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">marks<span class="token punctuation">[</span><span class="token number">2</span><span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token number">98</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token comment">// 定义和初始化</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>array<span class="token operator"><</span><span class="token keyword">int</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token operator">></span> marks <span class="token operator">=</span> <span class="token punctuation">{</span><span class="token number">92</span><span class="token punctuation">,</span> <span class="token number">97</span><span class="token punctuation">,</span> <span class="token number">98</span><span class="token punctuation">}</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token comment">// 有空成员</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>array<span class="token operator"><</span><span class="token keyword">int</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token operator">></span> marks <span class="token operator">=</span> <span class="token punctuation">{</span><span class="token number">92</span><span class="token punctuation">,</span> <span class="token number">97</span><span class="token punctuation">}</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> marks<span class="token punctuation">[</span><span class="token number">2</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token comment">// 输出: 0</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="操控"><a aria-hidden="true" tabindex="-1" href="#操控"><span class="icon icon-link"></span></a>操控</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line">┌─────┬─────┬─────┬─────┬─────┬─────┐
|
||
</span><span class="code-line"><span class="token operator">|</span> <span class="token number">92</span> <span class="token operator">|</span> <span class="token number">97</span> <span class="token operator">|</span> <span class="token number">98</span> <span class="token operator">|</span> <span class="token number">99</span> <span class="token operator">|</span> <span class="token number">98</span> <span class="token operator">|</span> <span class="token number">94</span> <span class="token operator">|</span>
|
||
</span><span class="code-line">└─────┴─────┴─────┴─────┴─────┴─────┘
|
||
</span><span class="code-line"> <span class="token number">0</span> <span class="token number">1</span> <span class="token number">2</span> <span class="token number">3</span> <span class="token number">4</span> <span class="token number">5</span>
|
||
</span></code></pre>
|
||
<hr>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line">std<span class="token double-colon punctuation">::</span>array<span class="token operator"><</span><span class="token keyword">int</span><span class="token punctuation">,</span> <span class="token number">6</span><span class="token operator">></span> marks <span class="token operator">=</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token number">92</span><span class="token punctuation">,</span> <span class="token number">97</span><span class="token punctuation">,</span> <span class="token number">98</span><span class="token punctuation">,</span> <span class="token number">99</span><span class="token punctuation">,</span> <span class="token number">98</span><span class="token punctuation">,</span> <span class="token number">94</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token comment">// 打印第一个元素</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> marks<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token comment">// 将第 2 个元素更改为 99</span>
|
||
</span><span class="code-line">marks<span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token number">99</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token comment">// 从用户那里获取输入</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>cin <span class="token operator">>></span> marks<span class="token punctuation">[</span><span class="token number">2</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="展示"><a aria-hidden="true" tabindex="-1" href="#展示"><span class="icon icon-link"></span></a>展示</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">char</span> ref<span class="token punctuation">[</span><span class="token number">5</span><span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token punctuation">{</span><span class="token char">'R'</span><span class="token punctuation">,</span> <span class="token char">'e'</span><span class="token punctuation">,</span> <span class="token char">'f'</span><span class="token punctuation">}</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token comment">// 基于范围的for循环</span>
|
||
</span><span class="code-line"><span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">const</span> <span class="token keyword">int</span> <span class="token operator">&</span>n <span class="token operator">:</span> ref<span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> std<span class="token double-colon punctuation">::</span><span class="token function">string</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span> n<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token comment">// 传统的for循环</span>
|
||
</span><span class="code-line"><span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">int</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> i <span class="token operator"><</span> <span class="token keyword">sizeof</span><span class="token punctuation">(</span>ref<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token operator">++</span>i<span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> ref<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="多维"><a aria-hidden="true" tabindex="-1" href="#多维"><span class="icon icon-link"></span></a>多维</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"> j0 j1 j2 j3 j4 j5
|
||
</span><span class="code-line"> ┌────┬────┬────┬────┬────┬────┐
|
||
</span><span class="code-line">i0 <span class="token operator">|</span> <span class="token number">1</span> <span class="token operator">|</span> <span class="token number">2</span> <span class="token operator">|</span> <span class="token number">3</span> <span class="token operator">|</span> <span class="token number">4</span> <span class="token operator">|</span> <span class="token number">5</span> <span class="token operator">|</span> <span class="token number">6</span> <span class="token operator">|</span>
|
||
</span><span class="code-line"> ├────┼────┼────┼────┼────┼────┤
|
||
</span><span class="code-line">i1 <span class="token operator">|</span> <span class="token number">6</span> <span class="token operator">|</span> <span class="token number">5</span> <span class="token operator">|</span> <span class="token number">4</span> <span class="token operator">|</span> <span class="token number">3</span> <span class="token operator">|</span> <span class="token number">2</span> <span class="token operator">|</span> <span class="token number">1</span> <span class="token operator">|</span>
|
||
</span><span class="code-line"> └────┴────┴────┴────┴────┴────┘
|
||
</span></code></pre>
|
||
<hr>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">int</span> x<span class="token punctuation">[</span><span class="token number">2</span><span class="token punctuation">]</span><span class="token punctuation">[</span><span class="token number">6</span><span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token punctuation">{</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token number">2</span><span class="token punctuation">,</span><span class="token number">3</span><span class="token punctuation">,</span><span class="token number">4</span><span class="token punctuation">,</span><span class="token number">5</span><span class="token punctuation">,</span><span class="token number">6</span><span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token punctuation">{</span><span class="token number">6</span><span class="token punctuation">,</span><span class="token number">5</span><span class="token punctuation">,</span><span class="token number">4</span><span class="token punctuation">,</span><span class="token number">3</span><span class="token punctuation">,</span><span class="token number">2</span><span class="token punctuation">,</span><span class="token number">1</span><span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">int</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> i <span class="token operator"><</span> <span class="token number">2</span><span class="token punctuation">;</span> <span class="token operator">++</span>i<span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">int</span> j <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> j <span class="token operator"><</span> <span class="token number">6</span><span class="token punctuation">;</span> <span class="token operator">++</span>j<span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> x<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">[</span>j<span class="token punctuation">]</span> <span class="token operator"><<</span> <span class="token string">" "</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> <span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token comment">// 输出: 1 2 3 4 5 6 6 5 4 3 2 1</span>
|
||
</span></code></pre>
|
||
</div></div></div></div></div><div class="wrap h2body-exist"><div class="wrap-header h2wrap"><h2 id="c-条件"><a aria-hidden="true" tabindex="-1" href="#c-条件"><span class="icon icon-link"></span></a>C++ 条件</h2><div class="wrap-body">
|
||
</div></div><div class="h2wrap-body"><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="if-clause"><a aria-hidden="true" tabindex="-1" href="#if-clause"><span class="icon icon-link"></span></a>If Clause</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">if</span> <span class="token punctuation">(</span>a <span class="token operator">==</span> <span class="token number">10</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token comment">// do something</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span></code></pre>
|
||
<hr>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">int</span> number <span class="token operator">=</span> <span class="token number">16</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token keyword">if</span> <span class="token punctuation">(</span>number <span class="token operator">%</span> <span class="token number">2</span> <span class="token operator">==</span> <span class="token number">0</span><span class="token punctuation">)</span>
|
||
</span><span class="code-line"><span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"even"</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token keyword">else</span>
|
||
</span><span class="code-line"><span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"odd"</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token comment">// 输出: even</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="else-if-语句"><a aria-hidden="true" tabindex="-1" href="#else-if-语句"><span class="icon icon-link"></span></a>Else if 语句</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">int</span> score <span class="token operator">=</span> <span class="token number">99</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token keyword">if</span> <span class="token punctuation">(</span>score <span class="token operator">==</span> <span class="token number">100</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"Superb"</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token keyword">else</span> <span class="token keyword">if</span> <span class="token punctuation">(</span>score <span class="token operator">>=</span> <span class="token number">90</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"Excellent"</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token keyword">else</span> <span class="token keyword">if</span> <span class="token punctuation">(</span>score <span class="token operator">>=</span> <span class="token number">80</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"Very Good"</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token keyword">else</span> <span class="token keyword">if</span> <span class="token punctuation">(</span>score <span class="token operator">>=</span> <span class="token number">70</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"Good"</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token keyword">else</span> <span class="token keyword">if</span> <span class="token punctuation">(</span>score <span class="token operator">>=</span> <span class="token number">60</span><span class="token punctuation">)</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"OK"</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token keyword">else</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"What?"</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-exist row-span-2"><div class="wrap-header h3wrap"><h3 id="运算符"><a aria-hidden="true" tabindex="-1" href="#运算符"><span class="icon icon-link"></span></a>运算符</h3><div class="wrap-body">
|
||
<!--rehype:wrap-class=row-span-2-->
|
||
<h4 id="关系运算符"><a aria-hidden="true" tabindex="-1" href="#关系运算符"><span class="icon icon-link"></span></a>关系运算符</h4>
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
<table><thead><tr><th align="left">:--</th><th>--</th></tr></thead><tbody><tr><td align="left"><code>a == b</code></td><td>a 等于 b</td></tr><tr><td align="left"><code>a != b</code></td><td>a 不等于 b</td></tr><tr><td align="left"><code>a < b</code></td><td>a 小于 b</td></tr><tr><td align="left"><code>a > b</code></td><td>a 大于 b</td></tr><tr><td align="left"><code>a <= b</code></td><td>a 小于或等于 b</td></tr><tr><td align="left"><code>a >= b</code></td><td>a 大于或等于 b</td></tr></tbody></table>
|
||
<h4 id="赋值运算符"><a aria-hidden="true" tabindex="-1" href="#赋值运算符"><span class="icon icon-link"></span></a>赋值运算符</h4>
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
<table><thead><tr><th align="left">范例</th><th>相当于</th></tr></thead><tbody><tr><td align="left"><code>a += b</code></td><td><em>Aka</em> <code>a = a + b</code></td></tr><tr><td align="left"><code>a -= b</code></td><td><em>Aka</em> <code>a = a - b</code></td></tr><tr><td align="left"><code>a *= b</code></td><td><em>Aka</em> <code>a = a * b</code></td></tr><tr><td align="left"><code>a /= b</code></td><td><em>Aka</em> <code>a = a / b</code></td></tr><tr><td align="left"><code>a %= b</code></td><td><em>Aka</em> <code>a = a % b</code></td></tr></tbody></table>
|
||
<h4 id="逻辑运算符"><a aria-hidden="true" tabindex="-1" href="#逻辑运算符"><span class="icon icon-link"></span></a>逻辑运算符</h4>
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
<table><thead><tr><th>Example</th><th>Meaning</th></tr></thead><tbody><tr><td><code>exp1 && exp2</code></td><td>Both are true <em>(AND)</em></td></tr><tr><td><code>exp1 || exp2</code></td><td>Either is true <em>(OR)</em></td></tr><tr><td><code>!exp</code></td><td><code>exp</code> is false <em>(NOT)</em></td></tr></tbody></table>
|
||
<h4 id="位运算符"><a aria-hidden="true" tabindex="-1" href="#位运算符"><span class="icon icon-link"></span></a>位运算符</h4>
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
<table><thead><tr><th>运算符</th><th>描述</th></tr></thead><tbody><tr><td><code>a & b</code></td><td>按位与</td></tr><tr><td><code>a | b</code></td><td>按位或</td></tr><tr><td><code>a ^ b</code></td><td>按位异或</td></tr><tr><td><code>~a</code></td><td>按位取反</td></tr><tr><td><code>a << b</code></td><td>左移</td></tr><tr><td><code>a >> b</code></td><td>右移</td></tr></tbody></table>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="三元运算符"><a aria-hidden="true" tabindex="-1" href="#三元运算符"><span class="icon icon-link"></span></a>三元运算符</h3><div class="wrap-body">
|
||
<pre><code class="code-highlight"><span class="code-line"> ┌── True ──┐
|
||
</span><span class="code-line">Result = Condition ? Exp1 : Exp2;
|
||
</span><span class="code-line"> └───── False ─────┘
|
||
</span></code></pre>
|
||
<hr>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">int</span> x <span class="token operator">=</span> <span class="token number">3</span><span class="token punctuation">,</span> y <span class="token operator">=</span> <span class="token number">5</span><span class="token punctuation">,</span> max<span class="token punctuation">;</span>
|
||
</span><span class="code-line">max <span class="token operator">=</span> <span class="token punctuation">(</span>x <span class="token operator">></span> y<span class="token punctuation">)</span> <span class="token operator">?</span> x <span class="token operator">:</span> y<span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token comment">// 输出: 5</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> max <span class="token operator"><<</span> std<span class="token double-colon punctuation">::</span>endl<span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
<hr>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">int</span> x <span class="token operator">=</span> <span class="token number">3</span><span class="token punctuation">,</span> y <span class="token operator">=</span> <span class="token number">5</span><span class="token punctuation">,</span> max<span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token keyword">if</span> <span class="token punctuation">(</span>x <span class="token operator">></span> y<span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> max <span class="token operator">=</span> x<span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> max <span class="token operator">=</span> y<span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token comment">// 输出: 5</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> max <span class="token operator"><<</span> std<span class="token double-colon punctuation">::</span>endl<span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="switch-语句"><a aria-hidden="true" tabindex="-1" href="#switch-语句"><span class="icon icon-link"></span></a>switch 语句</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">int</span> num <span class="token operator">=</span> <span class="token number">2</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token keyword">switch</span> <span class="token punctuation">(</span>num<span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token keyword">case</span> <span class="token number">0</span><span class="token operator">:</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"Zero"</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> <span class="token keyword">break</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> <span class="token keyword">case</span> <span class="token number">1</span><span class="token operator">:</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"One"</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> <span class="token keyword">break</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> <span class="token keyword">case</span> <span class="token number">2</span><span class="token operator">:</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"Two"</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> <span class="token keyword">break</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> <span class="token keyword">case</span> <span class="token number">3</span><span class="token operator">:</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"Three"</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> <span class="token keyword">break</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> <span class="token keyword">default</span><span class="token operator">:</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"What?"</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> <span class="token keyword">break</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span></code></pre>
|
||
</div></div></div></div></div><div class="wrap h2body-exist"><div class="wrap-header h2wrap"><h2 id="c-循环"><a aria-hidden="true" tabindex="-1" href="#c-循环"><span class="icon icon-link"></span></a>C++ 循环</h2><div class="wrap-body">
|
||
</div></div><div class="h2wrap-body"><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="while"><a aria-hidden="true" tabindex="-1" href="#while"><span class="icon icon-link"></span></a>While</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">int</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token keyword">while</span> <span class="token punctuation">(</span>i <span class="token operator"><</span> <span class="token number">6</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> i<span class="token operator">++</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token comment">// 输出: 012345</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="do-while"><a aria-hidden="true" tabindex="-1" href="#do-while"><span class="icon icon-link"></span></a>Do-while</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">int</span> i <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token keyword">do</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> i<span class="token operator">++</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span> <span class="token keyword">while</span> <span class="token punctuation">(</span>i <span class="token operator"><=</span> <span class="token number">5</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token comment">// 输出: 12345</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="continue-语句"><a aria-hidden="true" tabindex="-1" href="#continue-语句"><span class="icon icon-link"></span></a>Continue 语句</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">int</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> i <span class="token operator"><</span> <span class="token number">10</span><span class="token punctuation">;</span> i<span class="token operator">++</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token keyword">if</span> <span class="token punctuation">(</span>i <span class="token operator">%</span> <span class="token number">2</span> <span class="token operator">==</span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token keyword">continue</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> <span class="token punctuation">}</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> i<span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span> <span class="token comment">// 输出: 13579</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="无限循环"><a aria-hidden="true" tabindex="-1" href="#无限循环"><span class="icon icon-link"></span></a>无限循环</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">while</span> <span class="token punctuation">(</span><span class="token boolean">true</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> <span class="token comment">// true or 1</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"无限循环"</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span></code></pre>
|
||
<hr>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token punctuation">;</span><span class="token punctuation">;</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"无限循环"</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span></code></pre>
|
||
<hr>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">for</span><span class="token punctuation">(</span><span class="token keyword">int</span> i <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">;</span> i <span class="token operator">></span> <span class="token number">0</span><span class="token punctuation">;</span> i<span class="token operator">++</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"infinite loop"</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="for_each-c11-起"><a aria-hidden="true" tabindex="-1" href="#for_each-c11-起"><span class="icon icon-link"></span></a>for_each (C++11 起)</h3><div class="wrap-body">
|
||
<pre class="wrap-text"><code class="language-cpp code-highlight"><span class="code-line"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span> <span class="token string"><iostream></span></span>
|
||
</span><span class="code-line"><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||
</span><span class="code-line"><span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token keyword">auto</span> print <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">(</span><span class="token keyword">int</span> num<span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> num <span class="token operator"><<</span> std<span class="token double-colon punctuation">::</span>endl<span class="token punctuation">;</span>
|
||
</span><span class="code-line"> <span class="token punctuation">}</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>array<span class="token operator"><</span><span class="token keyword">int</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token operator">></span> arr <span class="token operator">=</span> <span class="token punctuation">{</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">}</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span><span class="token function">for_each</span><span class="token punctuation">(</span>arr<span class="token punctuation">.</span><span class="token function">begin</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span> arr<span class="token punctuation">.</span><span class="token function">end</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span> print<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> <span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span></code></pre>
|
||
<!--rehype:className=wrap-text-->
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="基于范围-c11-起"><a aria-hidden="true" tabindex="-1" href="#基于范围-c11-起"><span class="icon icon-link"></span></a>基于范围 (C++11 起)</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">int</span> n <span class="token operator">:</span> <span class="token punctuation">{</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">}</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> n <span class="token operator"><<</span> <span class="token string">" "</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token comment">// 输出: 1 2 3 4 5</span>
|
||
</span></code></pre>
|
||
<hr>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line">std<span class="token double-colon punctuation">::</span>string hello <span class="token operator">=</span> <span class="token string">"Quick Reference.ME"</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">char</span> c<span class="token operator">:</span> hello<span class="token punctuation">)</span>
|
||
</span><span class="code-line"><span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> c <span class="token operator"><<</span> <span class="token string">" "</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token comment">// 输出: Q u i c k R e f . M E</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="中断语句"><a aria-hidden="true" tabindex="-1" href="#中断语句"><span class="icon icon-link"></span></a>中断语句</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">int</span> password<span class="token punctuation">,</span> times <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token keyword">while</span> <span class="token punctuation">(</span>password <span class="token operator">!=</span> <span class="token number">1234</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token keyword">if</span> <span class="token punctuation">(</span>times<span class="token operator">++</span> <span class="token operator">>=</span> <span class="token number">3</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"Locked!\n"</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> <span class="token keyword">break</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> <span class="token punctuation">}</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"Password: "</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cin <span class="token operator">>></span> password<span class="token punctuation">;</span> <span class="token comment">// input</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="several-variations"><a aria-hidden="true" tabindex="-1" href="#several-variations"><span class="icon icon-link"></span></a>Several variations</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">int</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">,</span> j <span class="token operator">=</span> <span class="token number">2</span><span class="token punctuation">;</span> i <span class="token operator"><</span> <span class="token number">3</span><span class="token punctuation">;</span> i<span class="token operator">++</span><span class="token punctuation">,</span> j<span class="token operator">--</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"i="</span> <span class="token operator"><<</span> i <span class="token operator"><<</span> <span class="token string">","</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"j="</span> <span class="token operator"><<</span> j <span class="token operator"><<</span> <span class="token string">";"</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token comment">// 输出: i=0,j=2;i=1,j=1;i=2,j=0;</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="auto"><a aria-hidden="true" tabindex="-1" href="#auto"><span class="icon icon-link"></span></a>auto</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line">std<span class="token double-colon punctuation">::</span> string s <span class="token operator">=</span> <span class="token string">"hello world"</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token keyword">for</span><span class="token punctuation">(</span><span class="token keyword">auto</span> c<span class="token operator">:</span> s<span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span> cout <span class="token operator"><<</span> c <span class="token operator"><<</span> <span class="token string">" "</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token comment">// 输出: h e l l o w o r l d</span>
|
||
</span></code></pre>
|
||
</div></div></div></div></div><div class="wrap h2body-exist"><div class="wrap-header h2wrap"><h2 id="c-函数"><a aria-hidden="true" tabindex="-1" href="#c-函数"><span class="icon icon-link"></span></a>C++ 函数</h2><div class="wrap-body">
|
||
</div></div><div class="h2wrap-body"><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="参数和返回"><a aria-hidden="true" tabindex="-1" href="#参数和返回"><span class="icon icon-link"></span></a>参数和返回</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span> <span class="token string"><iostream></span></span>
|
||
</span><span class="code-line"><span class="token keyword">int</span> <span class="token function">add</span><span class="token punctuation">(</span><span class="token keyword">int</span> a<span class="token punctuation">,</span> <span class="token keyword">int</span> b<span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token keyword">return</span> a <span class="token operator">+</span> b<span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token function">add</span><span class="token punctuation">(</span><span class="token number">10</span><span class="token punctuation">,</span> <span class="token number">20</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span></code></pre>
|
||
<p><code>add</code> 是一个接受 2 个整数并返回整数的函数</p>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="重载"><a aria-hidden="true" tabindex="-1" href="#重载"><span class="icon icon-link"></span></a>重载</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">void</span> <span class="token function">fun</span><span class="token punctuation">(</span>string a<span class="token punctuation">,</span> string b<span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> a <span class="token operator">+</span> <span class="token string">" "</span> <span class="token operator">+</span> b<span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token keyword">void</span> <span class="token function">fun</span><span class="token punctuation">(</span>string a<span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> a<span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token keyword">void</span> <span class="token function">fun</span><span class="token punctuation">(</span><span class="token keyword">int</span> a<span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> a<span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="内置函数"><a aria-hidden="true" tabindex="-1" href="#内置函数"><span class="icon icon-link"></span></a>内置函数</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span> <span class="token string"><iostream></span></span>
|
||
</span><span class="code-line"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span> <span class="token string"><cmath></span> <span class="token comment">// 导入库</span></span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token comment">// sqrt() 来自 cmath</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token function">sqrt</span><span class="token punctuation">(</span><span class="token number">9</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist col-span-2"><div class="wrap-header h3wrap"><h3 id="lambda-表达式"><a aria-hidden="true" tabindex="-1" href="#lambda-表达式"><span class="icon icon-link"></span></a>Lambda 表达式</h3><div class="wrap-body">
|
||
<!--rehype:wrap-class=col-span-2-->
|
||
<p>Lambda 表达式可以在函数内定义，可以理解为在函数内定义的临时函数。格式：</p>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">auto</span> func <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-></span> return_type <span class="token punctuation">{</span> <span class="token punctuation">}</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
<ul class="style-timeline">
|
||
<li>
|
||
<p><code>[]</code>为捕获列表，能够捕获其所在函数的局部变量</p>
|
||
<ul>
|
||
<li>
|
||
<p>一个空的捕获列表代表Lambda表达式不捕获任何的变量</p>
|
||
</li>
|
||
<li>
|
||
<p>对于值捕获，直接在中括号中填写要捕获的变量即可：</p>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">int</span> val <span class="token operator">=</span> <span class="token number">5</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token keyword">auto</span> func <span class="token operator">=</span> <span class="token punctuation">[</span>val<span class="token punctuation">]</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-></span> return_type <span class="token punctuation">{</span> <span class="token punctuation">}</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
</li>
|
||
</ul>
|
||
</li>
|
||
<li>
|
||
<p>对于引用捕获，需要在捕获的变量前添加<code>&</code>：</p>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line">string <span class="token function">str</span><span class="token punctuation">(</span><span class="token string">"hello world!"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token keyword">auto</span> func <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token operator">&</span>str<span class="token punctuation">]</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-></span> return_type <span class="token punctuation">{</span> <span class="token punctuation">}</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
</li>
|
||
<li>
|
||
<p>如果变量太多，需要编译器根据我们编写的代码自动捕获，可以采用隐式捕获的方式。</p>
|
||
<ul>
|
||
<li>
|
||
<p>全部值捕获：</p>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">int</span> val1<span class="token punctuation">,</span> val2<span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token keyword">auto</span> func <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token operator">=</span><span class="token punctuation">]</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-></span> <span class="token keyword">int</span>
|
||
</span><span class="code-line"> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token keyword">return</span> val1 <span class="token operator">+</span> val2<span class="token punctuation">;</span>
|
||
</span><span class="code-line"> <span class="token punctuation">}</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
</li>
|
||
<li>
|
||
<p>全部引用捕获：</p>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line">string <span class="token function">str1</span><span class="token punctuation">(</span><span class="token string">"hello"</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token function">str2</span><span class="token punctuation">(</span><span class="token string">"word!"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token keyword">auto</span> func <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token operator">&</span><span class="token punctuation">]</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-></span> string
|
||
</span><span class="code-line"> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token keyword">return</span> str1 <span class="token operator">+</span> str2<span class="token punctuation">;</span>
|
||
</span><span class="code-line"> <span class="token punctuation">}</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
</li>
|
||
<li>
|
||
<p>混合隐式捕获：</p>
|
||
<p>如果希望对一部分变量采用值捕获，对其他变量采用引用捕获，可以混合使用：</p>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">int</span> val1 <span class="token operator">=</span> <span class="token number">123</span><span class="token punctuation">,</span> val2 <span class="token operator">=</span> <span class="token number">456</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">string <span class="token function">str1</span><span class="token punctuation">(</span><span class="token string">"123"</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token function">str2</span><span class="token punctuation">(</span><span class="token number">456</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token keyword">auto</span> func1 <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token operator">=</span><span class="token punctuation">,</span> <span class="token operator">&</span>str1<span class="token punctuation">]</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-></span> <span class="token keyword">int</span>
|
||
</span><span class="code-line"> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token keyword">return</span> val1 <span class="token operator">==</span> std<span class="token double-colon punctuation">::</span><span class="token function">stoi</span><span class="token punctuation">(</span>str1<span class="token punctuation">)</span>
|
||
</span><span class="code-line"> <span class="token operator">?</span> val1 <span class="token operator">:</span> val2<span class="token punctuation">;</span>
|
||
</span><span class="code-line"> <span class="token punctuation">}</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token keyword">auto</span> func2 <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token operator">&</span><span class="token punctuation">,</span> val1<span class="token punctuation">]</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-></span> string
|
||
</span><span class="code-line"> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token keyword">return</span> str1 <span class="token operator">==</span> std<span class="token double-colon punctuation">::</span><span class="token function">to_string</span><span class="token punctuation">(</span>val1<span class="token punctuation">)</span>
|
||
</span><span class="code-line"> <span class="token operator">?</span> str1 <span class="token operator">:</span> str2<span class="token punctuation">;</span>
|
||
</span><span class="code-line"> <span class="token punctuation">}</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
</li>
|
||
</ul>
|
||
</li>
|
||
<li>
|
||
<p><code>()</code> 是参数列表，我们只需要按照普通函数的使用方法来使用即可</p>
|
||
</li>
|
||
<li>
|
||
<p><code>return_type</code> 是函数的返回类型，<code>-> return_type</code> 可以不写，编译器会自动推导</p>
|
||
</li>
|
||
<li>
|
||
<p><code>{}</code> 中的内容就是函数体，依照普通函数的使用方法使用即可</p>
|
||
</li>
|
||
</ul>
|
||
<!--rehype:className=style-timeline-->
|
||
<p>此处给出一个 Lambda 表达式的实际使用例子(当然可以使用 <code>str::copy</code>):</p>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token comment">// vec中包含1, 2, 3, 4, 5</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>vector<span class="token operator"><</span><span class="token keyword">int</span><span class="token operator">></span> <span class="token function">vec</span><span class="token punctuation">(</span><span class="token punctuation">{</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span><span class="token function">for_each</span><span class="token punctuation">(</span>vec<span class="token punctuation">.</span><span class="token function">begin</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span> vec<span class="token punctuation">.</span><span class="token function">end</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||
</span><span class="code-line"> <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">(</span><span class="token keyword">int</span><span class="token operator">&</span> ele<span class="token punctuation">)</span> <span class="token operator">-></span> <span class="token keyword">void</span>
|
||
</span><span class="code-line"> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> ele
|
||
</span><span class="code-line"> <span class="token operator"><<</span> <span class="token string">" "</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> <span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
</div></div></div></div></div><div class="wrap h2body-exist"><div class="wrap-header h2wrap"><h2 id="c智能指针"><a aria-hidden="true" tabindex="-1" href="#c智能指针"><span class="icon icon-link"></span></a>C++智能指针</h2><div class="wrap-body">
|
||
</div></div><div class="h2wrap-body"><div class="wrap h3body-not-exist row-span-2"><div class="wrap-header h3wrap"><h3 id="智能指针基础"><a aria-hidden="true" tabindex="-1" href="#智能指针基础"><span class="icon icon-link"></span></a>智能指针基础</h3><div class="wrap-body">
|
||
<!--rehype:wrap-class=row-span-2-->
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span> <span class="token string"><memory></span></span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment">// 创建独占所有权的指针</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>unique_ptr<span class="token operator"><</span><span class="token keyword">int</span><span class="token operator">></span> p1 <span class="token operator">=</span> std<span class="token double-colon punctuation">::</span><span class="token generic-function"><span class="token function">make_unique</span><span class="token generic class-name"><span class="token operator"><</span><span class="token keyword">int</span><span class="token operator">></span></span></span><span class="token punctuation">(</span><span class="token number">42</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token comment">// 不能复制，只能移动</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>unique_ptr<span class="token operator"><</span><span class="token keyword">int</span><span class="token operator">></span> p2 <span class="token operator">=</span> std<span class="token double-colon punctuation">::</span><span class="token function">move</span><span class="token punctuation">(</span>p1<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token comment">// p1 现在为 nullptr</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment">// 创建共享所有权的指针</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>shared_ptr<span class="token operator"><</span><span class="token keyword">int</span><span class="token operator">></span> sp1 <span class="token operator">=</span> std<span class="token double-colon punctuation">::</span><span class="token generic-function"><span class="token function">make_shared</span><span class="token generic class-name"><span class="token operator"><</span><span class="token keyword">int</span><span class="token operator">></span></span></span><span class="token punctuation">(</span><span class="token number">42</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token comment">// 可以复制，引用计数增加</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>shared_ptr<span class="token operator"><</span><span class="token keyword">int</span><span class="token operator">></span> sp2 <span class="token operator">=</span> sp1<span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token comment">// 获取引用计数</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> sp1<span class="token punctuation">.</span><span class="token function">use_count</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 输出: 2</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment">// 创建弱引用，不增加引用计数</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>weak_ptr<span class="token operator"><</span><span class="token keyword">int</span><span class="token operator">></span> wp <span class="token operator">=</span> sp1<span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="unique_ptr"><a aria-hidden="true" tabindex="-1" href="#unique_ptr"><span class="icon icon-link"></span></a>unique_ptr</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token comment">// 创建方式1：使用 make_unique (C++14)</span>
|
||
</span><span class="code-line"><span class="token keyword">auto</span> p1 <span class="token operator">=</span> std<span class="token double-colon punctuation">::</span><span class="token generic-function"><span class="token function">make_unique</span><span class="token generic class-name"><span class="token operator"><</span><span class="token keyword">int</span><span class="token operator">></span></span></span><span class="token punctuation">(</span><span class="token number">42</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment">// 创建方式2：直接构造</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>unique_ptr<span class="token operator"><</span><span class="token keyword">int</span><span class="token operator">></span> <span class="token function">p2</span><span class="token punctuation">(</span><span class="token keyword">new</span> <span class="token keyword">int</span><span class="token punctuation">(</span><span class="token number">42</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment">// 访问资源</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token operator">*</span>p1 <span class="token operator"><<</span> std<span class="token double-colon punctuation">::</span>endl<span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token operator">*</span>p1 <span class="token operator">=</span> <span class="token number">100</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment">// 获取原始指针（不转移所有权）</span>
|
||
</span><span class="code-line"><span class="token keyword">int</span><span class="token operator">*</span> raw <span class="token operator">=</span> p1<span class="token punctuation">.</span><span class="token function">get</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment">// 释放所有权并返回原始指针</span>
|
||
</span><span class="code-line"><span class="token keyword">int</span><span class="token operator">*</span> released <span class="token operator">=</span> p1<span class="token punctuation">.</span><span class="token function">release</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token comment">// p1 现在为 nullptr</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment">// 替换管理的对象</span>
|
||
</span><span class="code-line">p1<span class="token punctuation">.</span><span class="token function">reset</span><span class="token punctuation">(</span><span class="token keyword">new</span> <span class="token keyword">int</span><span class="token punctuation">(</span><span class="token number">50</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="shared_ptr"><a aria-hidden="true" tabindex="-1" href="#shared_ptr"><span class="icon icon-link"></span></a>shared_ptr</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token comment">// 创建方式1：使用 make_shared</span>
|
||
</span><span class="code-line"><span class="token keyword">auto</span> sp1 <span class="token operator">=</span> std<span class="token double-colon punctuation">::</span><span class="token generic-function"><span class="token function">make_shared</span><span class="token generic class-name"><span class="token operator"><</span><span class="token keyword">int</span><span class="token operator">></span></span></span><span class="token punctuation">(</span><span class="token number">42</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment">// 创建方式2：直接构造</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>shared_ptr<span class="token operator"><</span><span class="token keyword">int</span><span class="token operator">></span> <span class="token function">sp2</span><span class="token punctuation">(</span><span class="token keyword">new</span> <span class="token keyword">int</span><span class="token punctuation">(</span><span class="token number">42</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment">// 复制和共享所有权</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>shared_ptr<span class="token operator"><</span><span class="token keyword">int</span><span class="token operator">></span> sp3 <span class="token operator">=</span> sp1<span class="token punctuation">;</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> sp1<span class="token punctuation">.</span><span class="token function">use_count</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 输出: 2</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment">// 访问资源</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token operator">*</span>sp1 <span class="token operator"><<</span> std<span class="token double-colon punctuation">::</span>endl<span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token operator">*</span>sp1 <span class="token operator">=</span> <span class="token number">100</span><span class="token punctuation">;</span> <span class="token comment">// 所有指向该资源的shared_ptr都会看到这个修改</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment">// 重置指针</span>
|
||
</span><span class="code-line">sp1<span class="token punctuation">.</span><span class="token function">reset</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// sp1变为nullptr，引用计数减1</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="weak_ptr"><a aria-hidden="true" tabindex="-1" href="#weak_ptr"><span class="icon icon-link"></span></a>weak_ptr</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line">std<span class="token double-colon punctuation">::</span>shared_ptr<span class="token operator"><</span><span class="token keyword">int</span><span class="token operator">></span> sp <span class="token operator">=</span> std<span class="token double-colon punctuation">::</span><span class="token generic-function"><span class="token function">make_shared</span><span class="token generic class-name"><span class="token operator"><</span><span class="token keyword">int</span><span class="token operator">></span></span></span><span class="token punctuation">(</span><span class="token number">42</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>weak_ptr<span class="token operator"><</span><span class="token keyword">int</span><span class="token operator">></span> wp <span class="token operator">=</span> sp<span class="token punctuation">;</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment">// 检查引用对象是否存在</span>
|
||
</span><span class="code-line"><span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token keyword">auto</span> locked <span class="token operator">=</span> wp<span class="token punctuation">.</span><span class="token function">lock</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token operator">*</span>locked <span class="token operator"><<</span> std<span class="token double-colon punctuation">::</span>endl<span class="token punctuation">;</span> <span class="token comment">// 输出: 42</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"对象已被销毁"</span> <span class="token operator"><<</span> std<span class="token double-colon punctuation">::</span>endl<span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment">// 检查是否过期</span>
|
||
</span><span class="code-line"><span class="token keyword">bool</span> is_expired <span class="token operator">=</span> wp<span class="token punctuation">.</span><span class="token function">expired</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// false</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment">// 获取引用计数</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> wp<span class="token punctuation">.</span><span class="token function">use_count</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 输出: 1</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment">// 当所有shared_ptr都被销毁时</span>
|
||
</span><span class="code-line">sp<span class="token punctuation">.</span><span class="token function">reset</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token keyword">if</span> <span class="token punctuation">(</span>wp<span class="token punctuation">.</span><span class="token function">expired</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"对象已被销毁"</span> <span class="token operator"><<</span> std<span class="token double-colon punctuation">::</span>endl<span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="循环引用问题"><a aria-hidden="true" tabindex="-1" href="#循环引用问题"><span class="icon icon-link"></span></a>循环引用问题</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">struct</span> <span class="token class-name">Node</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>string name<span class="token punctuation">;</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>shared_ptr<span class="token operator"><</span>Node<span class="token operator">></span> next<span class="token punctuation">;</span>
|
||
</span><span class="code-line"> <span class="token comment">// 使用weak_ptr避免循环引用</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>weak_ptr<span class="token operator"><</span>Node<span class="token operator">></span> parent<span class="token punctuation">;</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"> <span class="token function">Node</span><span class="token punctuation">(</span><span class="token keyword">const</span> std<span class="token double-colon punctuation">::</span>string<span class="token operator">&</span> n<span class="token punctuation">)</span> <span class="token operator">:</span> <span class="token function">name</span><span class="token punctuation">(</span>n<span class="token punctuation">)</span> <span class="token punctuation">{</span><span class="token punctuation">}</span>
|
||
</span><span class="code-line"> <span class="token operator">~</span><span class="token function">Node</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"销毁: "</span> <span class="token operator"><<</span> name <span class="token operator"><<</span> std<span class="token double-colon punctuation">::</span>endl<span class="token punctuation">;</span> <span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment">// 创建循环引用</span>
|
||
</span><span class="code-line"><span class="token keyword">void</span> <span class="token function">createCycle</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token keyword">auto</span> node1 <span class="token operator">=</span> std<span class="token double-colon punctuation">::</span><span class="token generic-function"><span class="token function">make_shared</span><span class="token generic class-name"><span class="token operator"><</span>Node<span class="token operator">></span></span></span><span class="token punctuation">(</span><span class="token string">"Node1"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> <span class="token keyword">auto</span> node2 <span class="token operator">=</span> std<span class="token double-colon punctuation">::</span><span class="token generic-function"><span class="token function">make_shared</span><span class="token generic class-name"><span class="token operator"><</span>Node<span class="token operator">></span></span></span><span class="token punctuation">(</span><span class="token string">"Node2"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"> node1<span class="token operator">-></span>next <span class="token operator">=</span> node2<span class="token punctuation">;</span>
|
||
</span><span class="code-line"> node2<span class="token operator">-></span>parent <span class="token operator">=</span> node1<span class="token punctuation">;</span> <span class="token comment">// 使用weak_ptr避免循环引用</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"> <span class="token comment">// 函数结束时，node1和node2会被正确销毁</span>
|
||
</span><span class="code-line"> <span class="token comment">// 如果parent也是shared_ptr，则会造成内存泄漏</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span></code></pre>
|
||
</div></div></div></div></div><div class="wrap h2body-exist"><div class="wrap-header h2wrap"><h2 id="c多线程"><a aria-hidden="true" tabindex="-1" href="#c多线程"><span class="icon icon-link"></span></a>C++多线程</h2><div class="wrap-body">
|
||
</div></div><div class="h2wrap-body"><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="多线程介绍"><a aria-hidden="true" tabindex="-1" href="#多线程介绍"><span class="icon icon-link"></span></a>多线程介绍</h3><div class="wrap-body">
|
||
<p>g++编译选项：<code>-std=c++11</code>。包含头文件：</p>
|
||
<ul>
|
||
<li><code>#include <thread></code>：C++多线程库</li>
|
||
<li><code>#include <mutex></code>：C++互斥量库</li>
|
||
<li><code>#include <future></code>：C++异步库</li>
|
||
</ul>
|
||
</div></div></div><div class="wrap h3body-not-exist row-span-2"><div class="wrap-header h3wrap"><h3 id="线程的创建"><a aria-hidden="true" tabindex="-1" href="#线程的创建"><span class="icon icon-link"></span></a>线程的创建</h3><div class="wrap-body">
|
||
<!--rehype:wrap-class=row-span-2-->
|
||
<p>以普通函数作为线程入口函数：</p>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">void</span> <span class="token function">entry_1</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> <span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token keyword">void</span> <span class="token function">entry_2</span><span class="token punctuation">(</span><span class="token keyword">int</span> val<span class="token punctuation">)</span> <span class="token punctuation">{</span> <span class="token punctuation">}</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>thread <span class="token function">my_thread_1</span><span class="token punctuation">(</span>entry_1<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>thread <span class="token function">my_thread_2</span><span class="token punctuation">(</span>entry_2<span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
<p>以类对象作为线程入口函数：</p>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">class</span> <span class="token class-name">Entry</span>
|
||
</span><span class="code-line"><span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token keyword">void</span> <span class="token keyword">operator</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> <span class="token punctuation">}</span>
|
||
</span><span class="code-line"> <span class="token keyword">void</span> <span class="token function">entry_function</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> <span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line">Entry entry<span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token comment">// 调用operator()()</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>thread <span class="token function">my_thread_1</span><span class="token punctuation">(</span>entry<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token comment">// 调用Entry::entry_function</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>thread <span class="token function">my_thread_2</span><span class="token punctuation">(</span><span class="token operator">&</span>Entry<span class="token double-colon punctuation">::</span>entry_function<span class="token punctuation">,</span> <span class="token operator">&</span>entry<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
<p>以lambda表达式作为线程入口函数：</p>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line">std<span class="token double-colon punctuation">::</span>thread <span class="token function">my_thread</span><span class="token punctuation">(</span><span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-></span> <span class="token keyword">void</span>
|
||
</span><span class="code-line"> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token comment">// ...</span>
|
||
</span><span class="code-line"> <span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="线程的销毁"><a aria-hidden="true" tabindex="-1" href="#线程的销毁"><span class="icon icon-link"></span></a>线程的销毁</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line">thread my_thread<span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token comment">// 阻塞</span>
|
||
</span><span class="code-line">my_thread<span class="token punctuation">.</span><span class="token function">join</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token comment">// 非阻塞</span>
|
||
</span><span class="code-line">my_thread<span class="token punctuation">.</span><span class="token function">detach</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="this_thread"><a aria-hidden="true" tabindex="-1" href="#this_thread"><span class="icon icon-link"></span></a><code>this_thread</code></h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token comment">// 获取当前线程ID</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>this_thread<span class="token double-colon punctuation">::</span><span class="token function">get_id</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token comment">// 使当前线程休眠一段指定时间</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>this_thread<span class="token double-colon punctuation">::</span><span class="token function">sleep_for</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token comment">// 使当前线程休眠到指定时间</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>this_thread<span class="token double-colon punctuation">::</span><span class="token function">sleep_until</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token comment">// 暂停当前线程的执行，让别的线程执行</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>this_thread<span class="token double-colon punctuation">::</span><span class="token function">yield</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-exist row-span-5"><div class="wrap-header h3wrap"><h3 id="锁"><a aria-hidden="true" tabindex="-1" href="#锁"><span class="icon icon-link"></span></a>锁</h3><div class="wrap-body">
|
||
<!--rehype:wrap-class=row-span-5-->
|
||
<blockquote>
|
||
<p><code>#include <mutex></code></p>
|
||
</blockquote>
|
||
<h4 id="锁的基本操作"><a aria-hidden="true" tabindex="-1" href="#锁的基本操作"><span class="icon icon-link"></span></a>锁的基本操作</h4>
|
||
<p>创建锁</p>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line">std<span class="token double-colon punctuation">::</span>mutex m<span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
<p>上锁</p>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line">m<span class="token punctuation">.</span><span class="token function">lock</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
<p>解锁</p>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line">m<span class="token punctuation">.</span><span class="token function">unlock</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
<p>尝试上锁：成功返回<code>true</code>，失败返回<code>false</code></p>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line">m<span class="token punctuation">.</span><span class="token function">try_lock</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
<p>解锁</p>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line">m<span class="token punctuation">.</span><span class="token function">unlock</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
<h4 id="更简单的锁--stdlock_guardmutex"><a aria-hidden="true" tabindex="-1" href="#更简单的锁--stdlock_guardmutex"><span class="icon icon-link"></span></a>更简单的锁 —— <code>std::lock_guard<Mutex></code></h4>
|
||
<p>构造时上锁，析构时解锁</p>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line">std<span class="token double-colon punctuation">::</span>mutex m<span class="token punctuation">;</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>lock_guard<span class="token operator"><</span>std<span class="token double-colon punctuation">::</span>mutex<span class="token operator">></span> <span class="token function">lock</span><span class="token punctuation">(</span>m<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
<p>额外参数：<code>std::adopt_lock</code>：只需解锁，无需上锁</p>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token comment">// 手动上锁</span>
|
||
</span><span class="code-line">m<span class="token punctuation">.</span><span class="token function">lock</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>lock_guard<span class="token operator"><</span>mutex<span class="token operator">></span> <span class="token function">lock</span><span class="token punctuation">(</span>m<span class="token punctuation">,</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>adopt_lock<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
<h4 id="unique_lockmutex"><a aria-hidden="true" tabindex="-1" href="#unique_lockmutex"><span class="icon icon-link"></span></a><code>unique_lock<Mutex></code></h4>
|
||
<p>构造上锁，析构解锁</p>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line">std<span class="token double-colon punctuation">::</span>mutex m<span class="token punctuation">;</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>unique_lock<span class="token operator"><</span>mutex<span class="token operator">></span> <span class="token function">lock</span><span class="token punctuation">(</span>m<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
<h5 id="stdadopt_lock"><a aria-hidden="true" tabindex="-1" href="#stdadopt_lock"><span class="icon icon-link"></span></a><code>std::adopt_lock</code></h5>
|
||
<p>只需解锁，无需上锁</p>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token comment">// 手动上锁</span>
|
||
</span><span class="code-line">m<span class="token punctuation">.</span><span class="token function">lock</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>unique_lock<span class="token operator"><</span>mutex<span class="token operator">></span> <span class="token function">lock</span><span class="token punctuation">(</span>m<span class="token punctuation">,</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>adopt_lock<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
<h5 id="stdtry_to_lock"><a aria-hidden="true" tabindex="-1" href="#stdtry_to_lock"><span class="icon icon-link"></span></a><code>std::try_to_lock</code></h5>
|
||
<p>尝试上锁，可以通过<code>std::unique_lock<Mutex>::owns_lock()</code>查看状态</p>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line">std<span class="token double-colon punctuation">::</span>unique_lock<span class="token operator"><</span>mutex<span class="token operator">></span> <span class="token function">lock</span><span class="token punctuation">(</span>m<span class="token punctuation">,</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>try_to_lock<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token keyword">if</span> <span class="token punctuation">(</span>lock<span class="token punctuation">.</span><span class="token function">owns_lock</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span>
|
||
</span><span class="code-line"><span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token comment">// 拿到了锁</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token keyword">else</span>
|
||
</span><span class="code-line"><span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token comment">// 没有</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span></code></pre>
|
||
<h5 id="stddefer_lock"><a aria-hidden="true" tabindex="-1" href="#stddefer_lock"><span class="icon icon-link"></span></a><code>std::defer_lock</code></h5>
|
||
<p>绑定锁，但不上锁</p>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line">std<span class="token double-colon punctuation">::</span>unique_lock<span class="token operator"><</span>mutex<span class="token operator">></span> <span class="token function">lock</span><span class="token punctuation">(</span>m<span class="token punctuation">,</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>defer_lock<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">lock<span class="token punctuation">.</span><span class="token function">lock</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">lock<span class="token punctuation">.</span><span class="token function">unlock</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
<h5 id="stdunique_lockmutexrelease"><a aria-hidden="true" tabindex="-1" href="#stdunique_lockmutexrelease"><span class="icon icon-link"></span></a><code>std::unique_lock<Mutex>::release</code></h5>
|
||
<p>返回所管理的<code>mutex</code>对象指针，**释放所有权。**一旦释放了所有权，那么如果原来互斥量处于互斥状态，程序员有责任手动解锁。</p>
|
||
<h4 id="stdcall_once"><a aria-hidden="true" tabindex="-1" href="#stdcall_once"><span class="icon icon-link"></span></a><code>std::call_once</code></h4>
|
||
<p>当多个线程通过这个函数调用一个可调用对象时，只会有一个线程成功调用。</p>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line">std<span class="token double-colon punctuation">::</span>once_flag flag<span class="token punctuation">;</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token keyword">void</span> <span class="token function">foo</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> <span class="token punctuation">}</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span><span class="token function">call_once</span><span class="token punctuation">(</span>flag<span class="token punctuation">,</span> foo<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-exist"><div class="wrap-header h3wrap"><h3 id="stdcondition_variable"><a aria-hidden="true" tabindex="-1" href="#stdcondition_variable"><span class="icon icon-link"></span></a><code>std::condition_variable</code></h3><div class="wrap-body">
|
||
<h4 id="创建条件变量"><a aria-hidden="true" tabindex="-1" href="#创建条件变量"><span class="icon icon-link"></span></a>创建条件变量</h4>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line">std<span class="token double-colon punctuation">::</span>condition_variable cond<span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
<h4 id="等待条件变量被通知"><a aria-hidden="true" tabindex="-1" href="#等待条件变量被通知"><span class="icon icon-link"></span></a>等待条件变量被通知</h4>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line">std<span class="token double-colon punctuation">::</span>unique_lock<span class="token operator"><</span>std<span class="token double-colon punctuation">::</span>mutex<span class="token operator">></span>
|
||
</span><span class="code-line"> lock<span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token keyword">extern</span> <span class="token keyword">bool</span> <span class="token function">predicate</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment">// 调用方式 1</span>
|
||
</span><span class="code-line">cond<span class="token punctuation">.</span><span class="token function">wait</span><span class="token punctuation">(</span>lock<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token comment">// 调用方式 2</span>
|
||
</span><span class="code-line">cond<span class="token punctuation">.</span><span class="token function">wait</span><span class="token punctuation">(</span>lock<span class="token punctuation">,</span> predicate<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
<hr>
|
||
<ul>
|
||
<li><code>wait</code>不断地尝试重新获取并加锁该互斥量，如果获取不到，它就卡在这里并反复尝试重新获取，如果获取到了，执行流程就继续往下走</li>
|
||
<li><code>wait</code>在获取到互斥量并加锁了互斥量之后：
|
||
<ul>
|
||
<li>如果<code>wait</code>被提供了可调用对象，那么就执行这个可调用对象：
|
||
<ul>
|
||
<li>如果返回值为<code>false</code>，那么<code>wait</code>继续加锁，直到再次被 notified</li>
|
||
<li>如果返回值为<code>true</code>，那么<code>wait</code>返回，继续执行流程</li>
|
||
</ul>
|
||
</li>
|
||
<li>如果<code>wait</code>没有第二个参数，那么直接返回，继续执行</li>
|
||
</ul>
|
||
</li>
|
||
</ul>
|
||
<h4 id="stdcondition_variablenotify_one"><a aria-hidden="true" tabindex="-1" href="#stdcondition_variablenotify_one"><span class="icon icon-link"></span></a><code>std::condition_variable::notify_one</code></h4>
|
||
<p><code>notify_one</code> 唤醒一个调用 <code>wait</code> 的线程。注意在唤醒之前要解锁，否则调用 <code>wait</code> 的线程也会因为无法加锁而阻塞。</p>
|
||
<h4 id="stdcondition_variablenotify_all"><a aria-hidden="true" tabindex="-1" href="#stdcondition_variablenotify_all"><span class="icon icon-link"></span></a><code>std::condition_variable::notify_all</code></h4>
|
||
<p>唤醒所有调用 <code>wait</code> 的线程。</p>
|
||
</div></div></div><div class="wrap h3body-exist row-span-5"><div class="wrap-header h3wrap"><h3 id="获取线程的运行结果"><a aria-hidden="true" tabindex="-1" href="#获取线程的运行结果"><span class="icon icon-link"></span></a>获取线程的运行结果</h3><div class="wrap-body">
|
||
<!--rehype:wrap-class=row-span-5-->
|
||
<blockquote>
|
||
<p><code>#include <future></code></p>
|
||
</blockquote>
|
||
<h4 id="创建异步任务"><a aria-hidden="true" tabindex="-1" href="#创建异步任务"><span class="icon icon-link"></span></a>创建异步任务</h4>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">double</span> <span class="token function">func</span><span class="token punctuation">(</span><span class="token keyword">int</span> val<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment">// 使用std::async创建异步任务</span>
|
||
</span><span class="code-line"><span class="token comment">// 使用std::future获取结果</span>
|
||
</span><span class="code-line"><span class="token comment">// future模板中存放返回值类型</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>future<span class="token operator"><</span><span class="token keyword">double</span><span class="token operator">></span> result <span class="token operator">=</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span><span class="token function">async</span><span class="token punctuation">(</span>func<span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
<h4 id="获取异步任务的返回值"><a aria-hidden="true" tabindex="-1" href="#获取异步任务的返回值"><span class="icon icon-link"></span></a>获取异步任务的返回值</h4>
|
||
<p>等待异步任务结束，但是不获取返回值：</p>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line">result<span class="token punctuation">.</span><span class="token function">wait</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
<p>获取异步任务的返回值：</p>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">int</span> val <span class="token operator">=</span> result<span class="token punctuation">.</span><span class="token function">get</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
<p>注：</p>
|
||
<ul>
|
||
<li><code>get()</code>返回右值，因此只可调用一次</li>
|
||
<li>只要调用上述任意函数，线程就会一直阻塞到返回值可用（入口函数运行结束）</li>
|
||
</ul>
|
||
<h4 id="stdasync-的额外参数"><a aria-hidden="true" tabindex="-1" href="#stdasync-的额外参数"><span class="icon icon-link"></span></a><code>std::async</code> 的额外参数</h4>
|
||
<p>额外参数可以被放在 <code>std::async</code> 的第一个参数位置，用于设定 <code>std::async</code> 的行为：</p>
|
||
<ul>
|
||
<li><code>std::launch::deferred</code>：入口函数的运行会被推迟到<code>std::future<T>::get()</code>或者<code>std::future<T>::wait()</code>被调用时。此时调用线程会直接运行线程入口函数，换言之，<strong>不会创建子线程</strong></li>
|
||
<li><code>std::launch::async</code>：立即创建子线程，并运行线程入口函数</li>
|
||
<li><code>std::launch::deferred | std::launch::async</code>：默认值，由系统自行决定</li>
|
||
</ul>
|
||
<h4 id="返回值的状态"><a aria-hidden="true" tabindex="-1" href="#返回值的状态"><span class="icon icon-link"></span></a>返回值的状态</h4>
|
||
<p>让当前线程等待一段时间（等待到指定时间点），以期待返回值准备好：</p>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">extern</span> <span class="token keyword">double</span> <span class="token function">foo</span><span class="token punctuation">(</span><span class="token keyword">int</span> val<span class="token punctuation">)</span> <span class="token punctuation">{</span><span class="token punctuation">}</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>future<span class="token operator"><</span><span class="token keyword">double</span><span class="token operator">></span> result <span class="token operator">=</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span><span class="token function">async</span><span class="token punctuation">(</span>foo<span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment">//返回值类型</span>
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>future_status status<span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token comment">// 等待一段时间</span>
|
||
</span><span class="code-line">status <span class="token operator">=</span> result<span class="token punctuation">.</span><span class="token function">wait_for</span><span class="token punctuation">(</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>chrono<span class="token double-colon punctuation">::</span><span class="token function">seconds</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>
|
||
</span><span class="code-line"> <span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token comment">// 等待到某一时间点</span>
|
||
</span><span class="code-line">status <span class="token operator">=</span> result<span class="token punctuation">.</span><span class="token function">wait_until</span><span class="token punctuation">(</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>chrono<span class="token double-colon punctuation">::</span><span class="token function">now</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">+</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>chrono<span class="token double-colon punctuation">::</span><span class="token function">seconds</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>
|
||
</span><span class="code-line"> <span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
<p>在指定的时间过去后，可以获取等待的结果：</p>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token comment">// 返回值已经准备好</span>
|
||
</span><span class="code-line"><span class="token keyword">if</span> <span class="token punctuation">(</span>status <span class="token operator">==</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>future_status<span class="token double-colon punctuation">::</span>ready<span class="token punctuation">)</span>
|
||
</span><span class="code-line"><span class="token punctuation">{</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token comment">// 超时：尚未准备好</span>
|
||
</span><span class="code-line"><span class="token keyword">else</span> <span class="token keyword">if</span> <span class="token punctuation">(</span>status <span class="token operator">==</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>future_status<span class="token double-colon punctuation">::</span>timeout<span class="token punctuation">)</span>
|
||
</span><span class="code-line"><span class="token punctuation">{</span> <span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token comment">// 尚未启动: std::launch::deferred</span>
|
||
</span><span class="code-line"><span class="token keyword">else</span> <span class="token keyword">if</span> <span class="token punctuation">(</span>status <span class="token operator">==</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>future_status<span class="token double-colon punctuation">::</span>deferred<span class="token punctuation">)</span>
|
||
</span><span class="code-line"><span class="token punctuation">{</span> <span class="token punctuation">}</span>
|
||
</span></code></pre>
|
||
<h4 id="多个返回值"><a aria-hidden="true" tabindex="-1" href="#多个返回值"><span class="icon icon-link"></span></a>多个返回值</h4>
|
||
<p>如果要多次获取结果，可以使用<code>std::shared_future</code>，其会返回结果的一个<strong>拷贝</strong>。</p>
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line">std<span class="token double-colon punctuation">::</span>shared_future<span class="token operator"><</span>T<span class="token operator">></span> result<span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
<p>对于不可拷贝对象，可以在<code>std::shared_future</code>中存储对象的指针，而非指针本身。</p>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="创建线程"><a aria-hidden="true" tabindex="-1" href="#创建线程"><span class="icon icon-link"></span></a>创建线程</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">void</span> <span class="token function">threadFunction</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token comment">// 线程函数体</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"From thread"</span> <span class="token operator"><<</span> std<span class="token double-colon punctuation">::</span>endl<span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token comment">// 创建线程并开始执行线程函数</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>thread <span class="token function">t</span><span class="token punctuation">(</span>threadFunction<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"> <span class="token comment">// 等待线程执行完毕</span>
|
||
</span><span class="code-line"> t<span class="token punctuation">.</span><span class="token function">join</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"> <span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="传递参数给线程函数"><a aria-hidden="true" tabindex="-1" href="#传递参数给线程函数"><span class="icon icon-link"></span></a>传递参数给线程函数</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">void</span> <span class="token function">threadFunction</span><span class="token punctuation">(</span><span class="token keyword">int</span> value<span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token comment">// 线程函数体</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"Received value: "</span> <span class="token operator"><<</span> value <span class="token operator"><<</span> std<span class="token double-colon punctuation">::</span>endl<span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token keyword">int</span> data <span class="token operator">=</span> <span class="token number">42</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>thread <span class="token function">t</span><span class="token punctuation">(</span>threadFunction<span class="token punctuation">,</span> data<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> t<span class="token punctuation">.</span><span class="token function">join</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> <span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="使用lambda表达式创建线程"><a aria-hidden="true" tabindex="-1" href="#使用lambda表达式创建线程"><span class="icon icon-link"></span></a>使用Lambda表达式创建线程</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token keyword">int</span> data <span class="token operator">=</span> <span class="token number">42</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>thread <span class="token function">t</span><span class="token punctuation">(</span><span class="token punctuation">[</span>data<span class="token punctuation">]</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token comment">// Lambda 表达式作为线程函数</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"Received value: "</span> <span class="token operator"><<</span> data <span class="token operator"><<</span> std<span class="token double-colon punctuation">::</span>endl<span class="token punctuation">;</span>
|
||
</span><span class="code-line"> <span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> t<span class="token punctuation">.</span><span class="token function">join</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> <span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="处理线程间的同步"><a aria-hidden="true" tabindex="-1" href="#处理线程间的同步"><span class="icon icon-link"></span></a><strong>处理线程间的同步：</strong></h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span> <span class="token string"><mutex></span></span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line">std<span class="token double-colon punctuation">::</span>mutex mtx<span class="token punctuation">;</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token keyword">void</span> <span class="token function">threadFunction</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>lock_guard<span class="token operator"><</span>std<span class="token double-colon punctuation">::</span>mutex<span class="token operator">></span> <span class="token function">lock</span><span class="token punctuation">(</span>mtx<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"Thread safe output."</span> <span class="token operator"><<</span> std<span class="token double-colon punctuation">::</span>endl<span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>thread <span class="token function">t1</span><span class="token punctuation">(</span>threadFunction<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>thread <span class="token function">t2</span><span class="token punctuation">(</span>threadFunction<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> t1<span class="token punctuation">.</span><span class="token function">join</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> t2<span class="token punctuation">.</span><span class="token function">join</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"> <span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="使用stdasync启动异步任务"><a aria-hidden="true" tabindex="-1" href="#使用stdasync启动异步任务"><span class="icon icon-link"></span></a><strong>使用<code>std::async</code>启动异步任务：</strong></h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span> <span class="token string"><future></span></span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token keyword">int</span> <span class="token function">taskFunction</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token comment">// 异步任务</span>
|
||
</span><span class="code-line"> <span class="token keyword">return</span> <span class="token number">42</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token comment">// 启动异步任务</span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>future<span class="token operator"><</span><span class="token keyword">int</span><span class="token operator">></span> fut <span class="token operator">=</span> std<span class="token double-colon punctuation">::</span><span class="token function">async</span><span class="token punctuation">(</span>std<span class="token double-colon punctuation">::</span>launch<span class="token double-colon punctuation">::</span>async<span class="token punctuation">,</span> taskFunction<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"> <span class="token comment">// 获取异步任务的结果</span>
|
||
</span><span class="code-line"> <span class="token keyword">int</span> result <span class="token operator">=</span> fut<span class="token punctuation">.</span><span class="token function">get</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"Result: "</span> <span class="token operator"><<</span> result <span class="token operator"><<</span> std<span class="token double-colon punctuation">::</span>endl<span class="token punctuation">;</span>
|
||
</span><span class="code-line"> <span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span></code></pre>
|
||
</div></div></div></div></div><div class="wrap h2body-exist"><div class="wrap-header h2wrap"><h2 id="c-预处理器"><a aria-hidden="true" tabindex="-1" href="#c-预处理器"><span class="icon icon-link"></span></a>C++ 预处理器</h2><div class="wrap-body">
|
||
</div></div><div class="h2wrap-body"><div class="wrap h3body-not-exist row-span-3"><div class="wrap-header h3wrap"><h3 id="预处理器"><a aria-hidden="true" tabindex="-1" href="#预处理器"><span class="icon icon-link"></span></a>预处理器</h3><div class="wrap-body">
|
||
<!--rehype:wrap-class=row-span-3-->
|
||
<ul class="style-none cols-2">
|
||
<li><a href="https://zh.cppreference.com/w/cpp/preprocessor/conditional">if</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/preprocessor/conditional">elif</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/preprocessor/conditional">else</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/preprocessor/conditional">endif</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/preprocessor/conditional">ifdef</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/preprocessor/conditional">ifndef</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/preprocessor/replace">define</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/preprocessor/replace">undef</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/preprocessor/include">include</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/preprocessor/line">line</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/preprocessor/error">error</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/preprocessor/impl">pragma</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/preprocessor/conditional">defined</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/feature_test">__has_include</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/feature_test">__has_cpp_attribute</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/export">export</a></li>
|
||
<li><a href="https://zh.cppreference.com/mwiki/index.php?title=cpp/keyword/import&action=edit&redlink=1">import</a></li>
|
||
<li><a href="https://zh.cppreference.com/mwiki/index.php?title=cpp/keyword/module&action=edit&redlink=1">module</a></li>
|
||
</ul>
|
||
<!--rehype:className=style-none cols-2-->
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="includes"><a aria-hidden="true" tabindex="-1" href="#includes"><span class="icon icon-link"></span></a>Includes</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span> <span class="token string">"iostream"</span></span>
|
||
</span><span class="code-line"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span> <span class="token string"><iostream></span></span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="defines"><a aria-hidden="true" tabindex="-1" href="#defines"><span class="icon icon-link"></span></a>Defines</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">define</span> <span class="token macro-name">FOO</span></span>
|
||
</span><span class="code-line"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">define</span> <span class="token macro-name">FOO</span> <span class="token string">"hello"</span></span>
|
||
</span><span class="code-line"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">undef</span> <span class="token expression">FOO</span></span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist row-span-2"><div class="wrap-header h3wrap"><h3 id="if"><a aria-hidden="true" tabindex="-1" href="#if"><span class="icon icon-link"></span></a>If</h3><div class="wrap-body">
|
||
<!--rehype:wrap-class=row-span-2-->
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">ifdef</span> <span class="token expression">DEBUG</span></span>
|
||
</span><span class="code-line"> std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"hi"</span> <span class="token operator"><<</span> std<span class="token double-colon punctuation">::</span>endl<span class="token punctuation">;</span>
|
||
</span><span class="code-line"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">elif</span> <span class="token expression">defined VERBOSE</span></span>
|
||
</span><span class="code-line"> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>
|
||
</span><span class="code-line"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">else</span></span>
|
||
</span><span class="code-line"> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>
|
||
</span><span class="code-line"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">endif</span></span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="error"><a aria-hidden="true" tabindex="-1" href="#error"><span class="icon icon-link"></span></a>Error</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">if</span> <span class="token expression">VERSION <span class="token operator">==</span> <span class="token number">2.0</span></span></span>
|
||
</span><span class="code-line"> <span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">error</span> <span class="token expression">Unsupported</span></span>
|
||
</span><span class="code-line"> <span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">warning</span> <span class="token expression">Not really supported</span></span>
|
||
</span><span class="code-line"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">endif</span></span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="宏"><a aria-hidden="true" tabindex="-1" href="#宏"><span class="icon icon-link"></span></a>宏</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">define</span> <span class="token macro-name function">DEG</span><span class="token expression"><span class="token punctuation">(</span>x<span class="token punctuation">)</span> <span class="token punctuation">(</span><span class="token punctuation">(</span>x<span class="token punctuation">)</span> <span class="token operator">*</span> <span class="token number">57.29</span><span class="token punctuation">)</span></span></span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="令牌连接"><a aria-hidden="true" tabindex="-1" href="#令牌连接"><span class="icon icon-link"></span></a>令牌连接</h3><div class="wrap-body">
|
||
<pre class="language-cpp"><code class="language-cpp code-highlight"><span class="code-line"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">define</span> <span class="token macro-name function">DST</span><span class="token expression"><span class="token punctuation">(</span>name<span class="token punctuation">)</span> name</span><span class="token punctuation">##</span><span class="token expression">_s name</span><span class="token punctuation">##</span><span class="token expression">_t</span></span>
|
||
</span><span class="code-line"><span class="token function">DST</span><span class="token punctuation">(</span>object<span class="token punctuation">)</span><span class="token punctuation">;</span> #<span class="token operator">=</span><span class="token operator">></span> object_s object_t<span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="字符串化"><a aria-hidden="true" tabindex="-1" href="#字符串化"><span class="icon icon-link"></span></a>字符串化</h3><div class="wrap-body">
|
||
<pre class="wrap-text"><code class="language-cpp code-highlight"><span class="code-line"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">define</span> <span class="token macro-name function">STR</span><span class="token expression"><span class="token punctuation">(</span>name<span class="token punctuation">)</span> #name</span></span>
|
||
</span><span class="code-line"><span class="token keyword">char</span> <span class="token operator">*</span> a <span class="token operator">=</span> <span class="token function">STR</span><span class="token punctuation">(</span>object<span class="token punctuation">)</span><span class="token punctuation">;</span> #<span class="token operator">=</span><span class="token operator">></span> <span class="token keyword">char</span> <span class="token operator">*</span> a <span class="token operator">=</span> <span class="token string">"object"</span><span class="token punctuation">;</span>
|
||
</span></code></pre>
|
||
<!--rehype:className=wrap-text-->
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="文件和行"><a aria-hidden="true" tabindex="-1" href="#文件和行"><span class="icon icon-link"></span></a>文件和行</h3><div class="wrap-body">
|
||
<pre class="wrap-text"><code class="language-cpp code-highlight"><span class="code-line"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">define</span> <span class="token macro-name function">LOG</span><span class="token expression"><span class="token punctuation">(</span>msg<span class="token punctuation">)</span> console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token constant">__FILE__</span><span class="token punctuation">,</span> <span class="token constant">__LINE__</span><span class="token punctuation">,</span> msg<span class="token punctuation">)</span></span></span>
|
||
</span><span class="code-line">#<span class="token operator">=</span><span class="token operator">></span> console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">"file.txt"</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token string">"hey"</span><span class="token punctuation">)</span>
|
||
</span></code></pre>
|
||
<!--rehype:className=wrap-text-->
|
||
</div></div></div></div></div><div class="wrap h2body-exist"><div class="wrap-header h2wrap"><h2 id="各种各样的"><a aria-hidden="true" tabindex="-1" href="#各种各样的"><span class="icon icon-link"></span></a>各种各样的</h2><div class="wrap-body">
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</div></div><div class="h2wrap-body"><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="转义序列"><a aria-hidden="true" tabindex="-1" href="#转义序列"><span class="icon icon-link"></span></a>转义序列</h3><div class="wrap-body">
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<table><thead><tr><th align="left">转义序列</th><th>说明</th></tr></thead><tbody><tr><td align="left"><code>\b</code></td><td>退格键</td></tr><tr><td align="left"><code>\f</code></td><td>换页</td></tr><tr><td align="left"><code>\n</code></td><td>换行</td></tr><tr><td align="left"><code>\r</code></td><td>返回</td></tr><tr><td align="left"><code>\t</code></td><td>水平制表符</td></tr><tr><td align="left"><code>\v</code></td><td>垂直制表符</td></tr><tr><td align="left"><code>\\</code></td><td>反斜杠</td></tr><tr><td align="left"><code>\'</code></td><td>单引号</td></tr><tr><td align="left"><code>\"</code></td><td>双引号</td></tr><tr><td align="left"><code>\?</code></td><td>问号</td></tr><tr><td align="left"><code>\0</code></td><td>空字符</td></tr></tbody></table>
|
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</div></div></div><div class="wrap h3body-not-exist row-span-2 col-span-2"><div class="wrap-header h3wrap"><h3 id="关键字"><a aria-hidden="true" tabindex="-1" href="#关键字"><span class="icon icon-link"></span></a>关键字</h3><div class="wrap-body">
|
||
<!--rehype:wrap-class=row-span-2 col-span-2-->
|
||
<ul class="style-none cols-5">
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/alignas">alignas</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/alignof">alignof</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/and">and</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/and_eq">and_eq</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/asm">asm</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/atomic_cancel">atomic_cancel</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/atomic_commit">atomic_commit</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/atomic_noexcept">atomic_noexcept</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/auto">auto</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/bitand">bitand</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/bitor">bitor</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/bool">bool</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/break">break</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/case">case</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/catch">catch</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/char">char</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/char8_t">char8_t</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/char16_t">char16_t</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/char32_t">char32_t</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/class">class</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/compl">compl</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/concept">concept</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/const">const</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/consteval">consteval</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/constexpr">constexpr</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/constinit">constinit</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/const_cast">const_cast</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/continue">continue</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/co_await">co_await</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/co_return">co_return</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/co_yield">co_yield</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/decltype">decltype</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/default">default</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/delete">delete</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/do">do</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/double">double</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/dynamic_cast">dynamic_cast</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/else">else</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/enum">enum</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/explicit">explicit</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/export">export</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/extern">extern</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/false">false</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/float">float</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/for">for</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/friend">friend</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/goto">goto</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/if">if</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/inline">inline</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/int">int</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/long">long</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/mutable">mutable</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/namespace">namespace</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/new">new</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/noexcept">noexcept</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/not">not</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/not_eq">not_eq</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/nullptr">nullptr</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/operator">operator</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/or">or</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/or_eq">or_eq</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/private">private</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/protected">protected</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/public">public</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/reflexpr">reflexpr</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/register">register</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/reinterpret_cast">reinterpret_cast</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/requires">requires</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/language/return">return</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/short">short</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/signed">signed</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/sizeof">sizeof</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/static">static</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/static_assert">static_assert</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/static_cast">static_cast</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/struct">struct</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/switch">switch</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/synchronized">synchronized</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/template">template</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/this">this</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/thread_local">thread_local</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/throw">throw</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/true">true</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/try">try</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/typedef">typedef</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/typeid">typeid</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/typename">typename</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/union">union</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/unsigned">unsigned</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/using">using</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/virtual">virtual</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/void">void</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/volatile">volatile</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/wchar_t">wchar_t</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/while">while</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/xor">xor</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/xor_eq">xor_eq</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/language/final">final</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/language/override">override</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/language/transactional_memory">transaction_safe</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/language/transactional_memory">transaction_safe_dynamic</a></li>
|
||
</ul>
|
||
<!--rehype:className=style-none cols-5-->
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="预处理器-1"><a aria-hidden="true" tabindex="-1" href="#预处理器-1"><span class="icon icon-link"></span></a>预处理器</h3><div class="wrap-body">
|
||
<ul class="style-none cols-2">
|
||
<li><a href="https://zh.cppreference.com/w/cpp/preprocessor/conditional">if</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/preprocessor/conditional">elif</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/preprocessor/conditional">else</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/preprocessor/conditional">endif</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/preprocessor/conditional">ifdef</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/preprocessor/conditional">ifndef</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/preprocessor/replace">define</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/preprocessor/replace">undef</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/preprocessor/include">include</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/preprocessor/line">line</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/preprocessor/error">error</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/preprocessor/impl">pragma</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/preprocessor/conditional">defined</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/feature_test">__has_include</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/feature_test">__has_cpp_attribute</a></li>
|
||
<li><a href="https://zh.cppreference.com/w/cpp/keyword/export">export</a></li>
|
||
<li><a href="https://zh.cppreference.com/mwiki/index.php?title=cpp/keyword/import&action=edit&redlink=1">import</a></li>
|
||
<li><a href="https://zh.cppreference.com/mwiki/index.php?title=cpp/keyword/module&action=edit&redlink=1">module</a></li>
|
||
</ul>
|
||
<!--rehype:className=style-none cols-2-->
|
||
</div></div></div></div></div><div class="wrap h2body-not-exist"><div class="wrap-header h2wrap"><h2 id="另见"><a aria-hidden="true" tabindex="-1" href="#另见"><span class="icon icon-link"></span></a>另见</h2><div class="wrap-body">
|
||
<ul>
|
||
<li><a href="https://hackingcpp.com/cpp/cheat_sheets.html">C++ Infographics & Cheat Sheets</a> <em>(hackingcpp.com)</em></li>
|
||
<li><a href="https://zh.cppreference.com/w/">C++ reference</a> <em>(cppreference.com)</em></li>
|
||
<li><a href="http://www.cplusplus.com/doc/tutorial/">C++ Language Tutorials</a> <em>(cplusplus.com)</em></li>
|
||
</ul>
|
||
</div></div><div class="h2wrap-body"></div></div></div><script src="https://giscus.app/client.js" data-repo="jaywcjlove/reference" data-repo-id="R_kgDOID2-Mw" data-category="Q&A" data-category-id="DIC_kwDOID2-M84CS5wo" data-mapping="pathname" data-strict="0" data-reactions-enabled="1" data-emit-metadata="0" data-input-position="bottom" data-theme="dark" data-lang="zh-CN" crossorigin="anonymous" async></script><div class="giscus"></div></div><footer class="footer-wrap"><footer class="max-container">© 2022 <a href="https://wangchujiang.com/#/app" target="_blank">Kenny Wang</a>.</footer></footer><script src="../data.js?v=1.8.3" defer></script><script src="../js/fuse.min.js?v=1.8.3" defer></script><script src="../js/main.js?v=1.8.3" defer></script><div id="mysearch"><div class="mysearch-box"><div class="mysearch-input"><div><svg xmlns="http://www.w3.org/2000/svg" height="1em" width="1em" viewBox="0 0 18 18">
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