title: preg_match: check birthday format (dd/mm/yyyy)
body: <p>How do I make the expression which checks the birthday input to match a format like this dd/mm/yyyy? Below is what I came out so far, but it takes this too if I put 99/99/9999!</p>
  
  <pre><code>if (!preg_match("/[0-9]{2}\/[0-9]{2}\/[0-9]{4}/", $cnt_birthday))
    {
     $error = true;
     echo '&lt;error elementid="cnt_birthday" message="BIRTHDAY - Only this birthday format - dd/mm/yyyy - is accepted."/&gt;';
    }
  </code></pre>
  
  <p>How can I make sure that its only 01 to 31 for dd and 01 to 12 for mm? but I am sure how to restrict yyyy... I think theoritical 9999 should be acceptable...  let me know if you have a better idea! </p>
  
  <p>thanks,
  Lau </p>