title: Calculate Distance between two chars
body: <p>Is there a built in function that can calculate the distance between 2 chars? for example:</p>
  
  <p>if i want to calculate the distance between <code>a</code> and <code>c</code> the result should be <code>1</code> because there is one letter in between <code>a</code> and <code>c</code>.</p>
  
  <p>I did a function to achieve that, but i need to know if there is a built in solution or a simpler one </p>
  
  <pre><code>function str_distance($a, $b){
      $cant = 0;
      while(true){
          if (++$a == $b)
              return $cant;
          $cant++;
      }
  }
  </code></pre>
  
  <p>But this wont work when calculating <code>z</code> to <code>b</code> or any calculations that gets to the end of the alphabet.</p>
  
  <p>Any suggestions?</p>