title: strlen() php function giving the wrong length of unicode characters
body: <p>I am trying to get the length of this unicode characters string</p>
  
  <pre><code>$text = 'نام سلطان م';
  $length = strlen($text);
  echo $length;
  </code></pre>
  
  <p>output</p>
  
  <pre><code>20
  </code></pre>
  
  <p>How it determines the length of unicode characters string?</p>