title: Php regular expression for date
body: <p>something is wrong in my php regular expression which is not accepting <code>0</code> before Month and date. My date formate is <code>MM/DD/YY</code>. It could be 6/6/2014 or 06/06/2014. </p>
  
  <pre><code>if(!empty($datepicker)){
      if(preg_match("/^([0-9]|1[0-2])\/([0-9]|[1-2][0-9]|3[0-1])\/[0-9]{4}$/", $datepicker) !==1)
          $err[] = "Invalid date of birth";
  }
  </code></pre>