- var_dump: documentation ( source)
- preg_match: documentation ( source)
<?php
$s = '<iframe width=800><embed width=300>fdgdfg</embed>sfsdfsdf</iframe>';
$matches = array();
var_dump( preg_match('~width=["\']?(\d+)["\']?~', $s, $matshes) );
var_dump($matshes);