title: explanation on what this function does... mainly just the regular expressions
body: <p>Can someone give me a brief explanation on this:</p>
  
  <pre><code>function id_zero($id)
      {
      if (preg_match("/^[0-9]+$/", $id) &amp;&amp; $id &gt; 0) return $id;
      return 0;
      }
  </code></pre>
  
  <p>mainly just this part: <code>"/^[0-9]+$/"</code></p>
  
  <p>It's looking for a number in beteween 0 and 9 and i'm really not sure what the other characters are doing...</p>
  
  <p>Thanks in advance.</p>