PHP Using RegEx to get substring of a string

$matches = array();
preg_match('/id=([0-9]+)\?/', $url, $matches);

This is safe for if the format changes. slandau's answer won't work if you ever have any other numbers in the URL.

php.net/preg-match

<?php
$string = "producturl.php?id=736375493?=tm";
preg_match('~id=(\d+)~', $string, $m );
var_dump($m[1]); // $m[1] is your string
?>