filesize

Example

 <span class="token php language-php"><span class="token delimiter important"><?php</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>

Output:

 20