ftruncate

实例

<span class="token php language-php"><span class="token delimiter important"><?php</span>
<span class="token comment">//检查文件大小</span>
<span class="token keyword">echo</span> <span class="token function">filesize</span><span class="token punctuation">(</span><span class="token string double-quoted-string">"test.txt"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">echo</span> <span class="token string double-quoted-string">"<br />"</span><span class="token punctuation">;</span>

<span class="token variable">$file</span> <span class="token operator">=</span> <span class="token function">fopen</span><span class="token punctuation">(</span><span class="token string double-quoted-string">"test.txt"</span><span class="token punctuation">,</span> <span class="token string double-quoted-string">"a+"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token function">ftruncate</span><span class="token punctuation">(</span><span class="token variable">$file</span><span class="token punctuation">,</span><span class="token number">100</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token function">fclose</span><span class="token punctuation">(</span><span class="token variable">$file</span><span class="token punctuation">)</span><span class="token punctuation">;</span>

<span class="token comment">//清空缓存，再次检查文件大小</span>
<span class="token function">clearstatcache</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">echo</span> <span class="token function">filesize</span><span class="token punctuation">(</span><span class="token string double-quoted-string">"test.txt"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token delimiter important">?></span></span>

输出类似：

792
100