title: Check text size in byte
body: <p>I have string </p>
  
  <pre><code>$text = "this is my text";
  </code></pre>
  
  <p>and i want to know the size(byte), not text length.</p>
  
  <p>so i tried to use </p>
  
  <blockquote>
    <p>filesize();</p>
  </blockquote>
  
  <p>but i get Error</p>
  
  <blockquote>
    <p>Warning: filesize(): stat failed for this is my text</p>
  </blockquote>
  
  <p>and if i tried to use </p>
  
  <blockquote>
    <p>mb_strlen()</p>
  </blockquote>
  
  <p>it only count the text lenght, not the size.</p>
  
  <p>How to know the text size ? i want the result something like "1024 bytes"</p>
  
  <p>Thanks</p>