about regex

[prakash]

i need to validate data using regex. the dati will be of 12 numeric on starting and 5 letters at ending

Here is what I made but think it is not correct.

<?php
$data=strtoupper($_POST['data']);
$validData=preg_replace("/^[0-9]{12}+[A-Z]{5}$/",'',$data)
?>

please let me correct

[effigy]

{12} is already quantifying [0-9], so you do not need the +. I would also replace $ with \z to prevent new lines from sneaking in.