doc: update docs/c.md. 877a763274

docs/c.html

@@ -1259,8 +1259,8 @@
 </span><span class="code-line">  <span class="token number">13</span><span class="token punctuation">,</span> <span class="token char">'B'</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">// 修改值</span>
-</span><span class="code-line">s1<span class="token punctuation">.</span>myNum <span class="token operator">=</span> <span class="token number">30</span><span class="token punctuation">;</span>
+</span><span class="code-line highlight-line">s1<span class="token punctuation">.</span>myNum <span class="token operator">=</span> <span class="token number">30</span><span class="token punctuation">;</span>
-</span><span class="code-line">s1<span class="token punctuation">.</span>myLetter <span class="token operator">=</span> <span class="token char">'C'</span><span class="token punctuation">;</span>
+</span><span class="code-line highlight-line">s1<span class="token punctuation">.</span>myLetter <span class="token operator">=</span> <span class="token char">'C'</span><span class="token punctuation">;</span>
 </span><span class="code-line"><span class="token comment">// 打印值</span>
 </span><span class="code-line"><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d %c %s"</span><span class="token punctuation">,</span>
 </span><span class="code-line">    s1<span class="token punctuation">.</span>myNum<span class="token punctuation">,</span>
@@ -1384,10 +1384,12 @@
 <table><thead><tr><th>模式 Mode</th><th>描述 Description</th></tr></thead><tbody><tr><td><code>r</code></td><td>以<code>读取</code>模式打开一个文本文件，允许读取文件</td></tr><tr><td><code>w</code></td><td>以<code>写</code>模式打开一个文本文件，允许写入文件</td></tr><tr><td><code>a</code></td><td>以<code>追加</code>模式打开一个文本文件<br>如果文件不存在，则会创建一个新文件</td></tr><tr><td><code>r+</code></td><td>以<code>读写</code>模式打开一个文本文件，允许读写文件</td></tr><tr><td><code>w+</code></td><td>以<code>读写</code>模式打开一个文本文件，允许读写文件</td></tr><tr><td><code>a+</code></td><td>以<code>读写</code>模式打开一个文本文件，允许读写文件</td></tr><tr><td><code>rb</code></td><td>以<code>读取</code>模式打开二进制文件</td></tr><tr><td><code>wb</code></td><td>以<code>写入</code>模式打开二进制文件</td></tr><tr><td><code>ab</code></td><td>以<code>追加</code>模式打开二进制文件</td></tr><tr><td><code>rb+</code></td><td>以<code>读写</code>模式打开二进制文件</td></tr><tr><td><code>wb+</code></td><td>以<code>读写</code>模式打开二进制文件</td></tr><tr><td><code>ab+</code></td><td>以<code>读写</code>模式打开二进制文件</td></tr></tbody></table>
 </div></div></div><div class="wrap"><div class="wrap-header h3wrap"><h3 id="打开文件fopen"><a aria-hidden="true" tabindex="-1" href="#打开文件fopen"><span class="icon icon-link"></span></a>打开文件：fopen()</h3><div class="wrap-body">
 <pre class="language-c"><code class="language-c 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">&#x3C;stdio.h></span></span>
+</span><span class="code-line">
 </span><span class="code-line"><span class="token keyword">void</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">  FILE <span class="token operator">*</span>fp<span class="token punctuation">;</span>
 </span><span class="code-line">  <span class="token keyword">char</span> ch<span class="token punctuation">;</span>
-</span><span class="code-line">  fp <span class="token operator">=</span> <span class="token function">fopen</span><span class="token punctuation">(</span><span class="token string">"file_handle.c"</span><span class="token punctuation">,</span> <span class="token string">"r"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
+</span><span class="code-line highlight-line">  fp <span class="token operator">=</span> <span class="token function">fopen</span><span class="token punctuation">(</span><span class="token string">"file_handle.c"</span><span class="token punctuation">,</span> <span class="token string">"r"</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">while</span> <span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
 </span><span class="code-line">    ch <span class="token operator">=</span> <span class="token function">fgetc</span><span class="token punctuation">(</span>fp<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>ch <span class="token operator">==</span> <span class="token constant">EOF</span><span class="token punctuation">)</span>
@@ -1399,11 +1401,13 @@
 </span></code></pre>
 <p>对文件执行所有操作后，必须关闭 <code>fclose()</code> 该文件</p>
 </div></div></div><div class="wrap"><div class="wrap-header h3wrap"><h3 id="写入文件fprintf"><a aria-hidden="true" tabindex="-1" href="#写入文件fprintf"><span class="icon icon-link"></span></a>写入文件：fprintf()</h3><div class="wrap-body">
-<pre class="language-c"><code class="language-c 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">&#x3C;stdio.h></span>  </span>
+<pre class="language-c"><code class="language-c 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">&#x3C;stdio.h></span></span>
+</span><span class="code-line">
 </span><span class="code-line"><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">  FILE <span class="token operator">*</span>fp<span class="token punctuation">;</span>
 </span><span class="code-line">  fp <span class="token operator">=</span> <span class="token function">fopen</span><span class="token punctuation">(</span><span class="token string">"file.txt"</span><span class="token punctuation">,</span> <span class="token string">"w"</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 打开文件</span>
-</span><span class="code-line">  <span class="token function">fprintf</span><span class="token punctuation">(</span>fp<span class="token punctuation">,</span> <span class="token string">"Hello file by fprintf...\n"</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 将数据写入文件</span>
+</span><span class="code-line">  <span class="token comment">// 将数据写入文件</span>
+</span><span class="code-line highlight-line">  <span class="token function">fprintf</span><span class="token punctuation">(</span>fp<span class="token punctuation">,</span> <span class="token string">"fprintf 的 Hello 文件..\n"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
 </span><span class="code-line">  <span class="token function">fclose</span><span class="token punctuation">(</span>fp<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 关闭文件  </span>
 </span><span class="code-line"><span class="token punctuation">}</span>  
 </span></code></pre>
@@ -1411,9 +1415,9 @@
 <pre class="language-c"><code class="language-c 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">&#x3C;stdio.h></span>  </span>
 </span><span class="code-line"><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">  FILE <span class="token operator">*</span>fp<span class="token punctuation">;</span>
-</span><span class="code-line">  <span class="token keyword">char</span> buff<span class="token punctuation">[</span><span class="token number">255</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token comment">// 创建 char 数组来存储文件数据</span>
+</span><span class="code-line">  <span class="token keyword">char</span> buff<span class="token punctuation">[</span><span class="token number">255</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token comment">// 创建char数组存储文件数据</span>
 </span><span class="code-line">  fp <span class="token operator">=</span> <span class="token function">fopen</span><span class="token punctuation">(</span><span class="token string">"file.txt"</span><span class="token punctuation">,</span> <span class="token string">"r"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
-</span><span class="code-line">  <span class="token keyword">while</span><span class="token punctuation">(</span><span class="token function">fscanf</span><span class="token punctuation">(</span>fp<span class="token punctuation">,</span> <span class="token string">"%s"</span><span class="token punctuation">,</span> buff<span class="token punctuation">)</span><span class="token operator">!=</span><span class="token constant">EOF</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
+</span><span class="code-line highlight-line">  <span class="token keyword">while</span><span class="token punctuation">(</span><span class="token function">fscanf</span><span class="token punctuation">(</span>fp<span class="token punctuation">,</span> <span class="token string">"%s"</span><span class="token punctuation">,</span> buff<span class="token punctuation">)</span><span class="token operator">!=</span><span class="token constant">EOF</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
 </span><span class="code-line">    <span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%s "</span><span class="token punctuation">,</span> buff<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 function">fclose</span><span class="token punctuation">(</span>fp<span class="token punctuation">)</span><span class="token punctuation">;</span>
@@ -1421,10 +1425,11 @@
 </span></code></pre>
 </div></div></div><div class="wrap"><div class="wrap-header h3wrap"><h3 id="写入文件fputc"><a aria-hidden="true" tabindex="-1" href="#写入文件fputc"><span class="icon icon-link"></span></a>写入文件：fputc()</h3><div class="wrap-body">
 <pre class="language-c"><code class="language-c 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">&#x3C;stdio.h></span></span>
+</span><span class="code-line">
 </span><span class="code-line"><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">  FILE <span class="token operator">*</span>fp<span class="token punctuation">;</span>
 </span><span class="code-line">  fp <span class="token operator">=</span> <span class="token function">fopen</span><span class="token punctuation">(</span><span class="token string">"file1.txt"</span><span class="token punctuation">,</span> <span class="token string">"w"</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 打开文件</span>
-</span><span class="code-line">  <span class="token function">fputc</span><span class="token punctuation">(</span><span class="token char">'a'</span><span class="token punctuation">,</span>fp<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 将单个字符写入文件</span>
+</span><span class="code-line highlight-line">  <span class="token function">fputc</span><span class="token punctuation">(</span><span class="token char">'a'</span><span class="token punctuation">,</span>fp<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 将单个字符写入文件</span>
 </span><span class="code-line">  <span class="token function">fclose</span><span class="token punctuation">(</span>fp<span class="token punctuation">)</span><span class="token punctuation">;</span>    <span class="token comment">// 关闭文件</span>
 </span><span class="code-line"><span class="token punctuation">}</span>
 </span></code></pre>
@@ -1436,7 +1441,7 @@
 </span><span class="code-line">  <span class="token keyword">char</span> c<span class="token punctuation">;</span>
 </span><span class="code-line">  <span class="token function">clrscr</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
 </span><span class="code-line">  fp<span class="token operator">=</span><span class="token function">fopen</span><span class="token punctuation">(</span><span class="token string">"myfile.txt"</span><span class="token punctuation">,</span> <span class="token string">"r"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
-</span><span class="code-line">  <span class="token keyword">while</span><span class="token punctuation">(</span><span class="token punctuation">(</span>c<span class="token operator">=</span><span class="token function">fgetc</span><span class="token punctuation">(</span>fp<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token operator">!=</span><span class="token constant">EOF</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
+</span><span class="code-line highlight-line">  <span class="token keyword">while</span><span class="token punctuation">(</span><span class="token punctuation">(</span>c<span class="token operator">=</span><span class="token function">fgetc</span><span class="token punctuation">(</span>fp<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token operator">!=</span><span class="token constant">EOF</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
 </span><span class="code-line">    <span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%c"</span><span class="token punctuation">,</span> c<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 function">fclose</span><span class="token punctuation">(</span>fp<span class="token punctuation">)</span><span class="token punctuation">;</span>
@@ -1446,11 +1451,12 @@
 </div></div></div><div class="wrap"><div class="wrap-header h3wrap"><h3 id="写入文件fputs"><a aria-hidden="true" tabindex="-1" href="#写入文件fputs"><span class="icon icon-link"></span></a>写入文件：fputs()</h3><div class="wrap-body">
 <pre class="language-c"><code class="language-c 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">&#x3C;stdio.h></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">&#x3C;conio.h></span></span>
+</span><span class="code-line">
 </span><span class="code-line"><span class="token keyword">void</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">  FILE <span class="token operator">*</span>fp<span class="token punctuation">;</span>
 </span><span class="code-line">  <span class="token function">clrscr</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
 </span><span class="code-line">  fp <span class="token operator">=</span> <span class="token function">fopen</span><span class="token punctuation">(</span><span class="token string">"myfile2.txt"</span><span class="token punctuation">,</span><span class="token string">"w"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
-</span><span class="code-line">  <span class="token function">fputs</span><span class="token punctuation">(</span><span class="token string">"hello c programming"</span><span class="token punctuation">,</span>fp<span class="token punctuation">)</span><span class="token punctuation">;</span>
+</span><span class="code-line highlight-line">  <span class="token function">fputs</span><span class="token punctuation">(</span><span class="token string">"hello c programming"</span><span class="token punctuation">,</span>fp<span class="token punctuation">)</span><span class="token punctuation">;</span>
 </span><span class="code-line">  <span class="token function">fclose</span><span class="token punctuation">(</span>fp<span class="token punctuation">)</span><span class="token punctuation">;</span>
 </span><span class="code-line">  <span class="token function">getch</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>
@@ -1458,13 +1464,14 @@
 </div></div></div><div class="wrap"><div class="wrap-header h3wrap"><h3 id="读取文件fgets"><a aria-hidden="true" tabindex="-1" href="#读取文件fgets"><span class="icon icon-link"></span></a>读取文件：fgets()</h3><div class="wrap-body">
 <pre class="language-c"><code class="language-c 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">&#x3C;stdio.h></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">&#x3C;conio.h></span></span>
+</span><span class="code-line">
 </span><span class="code-line"><span class="token keyword">void</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">  FILE <span class="token operator">*</span>fp<span class="token punctuation">;</span>
 </span><span class="code-line">  <span class="token keyword">char</span> text<span class="token punctuation">[</span><span class="token number">300</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
 </span><span class="code-line">  <span class="token function">clrscr</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">  fp<span class="token operator">=</span><span class="token function">fopen</span><span class="token punctuation">(</span><span class="token string">"myfile2.txt"</span><span class="token punctuation">,</span> <span class="token string">"r"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
-</span><span class="code-line">  <span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%s"</span><span class="token punctuation">,</span> <span class="token function">fgets</span><span class="token punctuation">(</span>text<span class="token punctuation">,</span> <span class="token number">200</span><span class="token punctuation">,</span> fp<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
+</span><span class="code-line highlight-line">  <span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%s"</span><span class="token punctuation">,</span> <span class="token function">fgets</span><span class="token punctuation">(</span>text<span class="token punctuation">,</span> <span class="token number">200</span><span class="token punctuation">,</span> fp<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
 </span><span class="code-line">  <span class="token function">fclose</span><span class="token punctuation">(</span>fp<span class="token punctuation">)</span><span class="token punctuation">;</span>
 </span><span class="code-line">  <span class="token function">getch</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>
@@ -1476,7 +1483,8 @@
 </span><span class="code-line">  fp <span class="token operator">=</span> <span class="token function">fopen</span><span class="token punctuation">(</span><span class="token string">"myfile.txt"</span><span class="token punctuation">,</span><span class="token string">"w+"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
 </span><span class="code-line">  <span class="token function">fputs</span><span class="token punctuation">(</span><span class="token string">"This is Book"</span><span class="token punctuation">,</span> fp<span class="token punctuation">)</span><span class="token punctuation">;</span>
 </span><span class="code-line">
-</span><span class="code-line">  <span class="token function">fseek</span><span class="token punctuation">(</span>fp<span class="token punctuation">,</span> <span class="token number">7</span><span class="token punctuation">,</span> <span class="token constant">SEEK_SET</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
+</span><span class="code-line">  <span class="token comment">// 将文件指针设置到给定位置</span>
+</span><span class="code-line highlight-line">  <span class="token function">fseek</span><span class="token punctuation">(</span>fp<span class="token punctuation">,</span> <span class="token number">7</span><span class="token punctuation">,</span> <span class="token constant">SEEK_SET</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
 </span><span class="code-line">  <span class="token function">fputs</span><span class="token punctuation">(</span><span class="token string">"Kenny Wong"</span><span class="token punctuation">,</span> fp<span class="token punctuation">)</span><span class="token punctuation">;</span>
 </span><span class="code-line">  <span class="token function">fclose</span><span class="token punctuation">(</span>fp<span class="token punctuation">)</span><span class="token punctuation">;</span>
 </span><span class="code-line"><span class="token punctuation">}</span>
@@ -1493,7 +1501,7 @@
 </span><span class="code-line">  <span class="token keyword">while</span><span class="token punctuation">(</span><span class="token punctuation">(</span>c<span class="token operator">=</span><span class="token function">fgetc</span><span class="token punctuation">(</span>fp<span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token operator">!=</span> <span class="token constant">EOF</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
 </span><span class="code-line">    <span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%c"</span><span class="token punctuation">,</span> c<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 function">rewind</span><span class="token punctuation">(</span>fp<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 将文件指针移动到文件的开头</span>
+</span><span class="code-line highlight-line">  <span class="token function">rewind</span><span class="token punctuation">(</span>fp<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 将文件指针移动到文件的开头</span>
 </span><span class="code-line">  <span class="token keyword">while</span><span class="token punctuation">(</span><span class="token punctuation">(</span>c<span class="token operator">=</span><span class="token function">fgetc</span><span class="token punctuation">(</span>fp<span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token operator">!=</span> <span class="token constant">EOF</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
 </span><span class="code-line">    <span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%c"</span><span class="token punctuation">,</span> c<span class="token punctuation">)</span><span class="token punctuation">;</span>
 </span><span class="code-line">  <span class="token punctuation">}</span>
@@ -1506,6 +1514,7 @@
 </div></div></div><div class="wrap"><div class="wrap-header h3wrap"><h3 id="ftell"><a aria-hidden="true" tabindex="-1" href="#ftell"><span class="icon icon-link"></span></a>ftell()</h3><div class="wrap-body">
 <pre class="language-c"><code class="language-c 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">&#x3C;stdio.h></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">&#x3C;conio.h></span></span>
+</span><span class="code-line">
 </span><span class="code-line"><span class="token keyword">void</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">   FILE <span class="token operator">*</span>fp<span class="token punctuation">;</span>
 </span><span class="code-line">   <span class="token keyword">int</span> length<span class="token punctuation">;</span>
@@ -1513,7 +1522,7 @@
 </span><span class="code-line">   fp <span class="token operator">=</span> <span class="token function">fopen</span><span class="token punctuation">(</span><span class="token string">"file.txt"</span><span class="token punctuation">,</span> <span class="token string">"r"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
 </span><span class="code-line">   <span class="token function">fseek</span><span class="token punctuation">(</span>fp<span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">,</span> <span class="token constant">SEEK_END</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
 </span><span class="code-line">
-</span><span class="code-line">   length <span class="token operator">=</span> <span class="token function">ftell</span><span class="token punctuation">(</span>fp<span class="token punctuation">)</span><span class="token punctuation">;</span>
+</span><span class="code-line highlight-line">   length <span class="token operator">=</span> <span class="token function">ftell</span><span class="token punctuation">(</span>fp<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 返回当前位置</span>
 </span><span class="code-line">
 </span><span class="code-line">   <span class="token function">fclose</span><span class="token punctuation">(</span>fp<span class="token punctuation">)</span><span class="token punctuation">;</span>
 </span><span class="code-line">   <span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"文件大小: %d bytes"</span><span class="token punctuation">,</span> length<span class="token punctuation">)</span><span class="token punctuation">;</span>