$re = '/^[1-9][^SLOIBZsloibz0-9][^SLOIBZsloibz][0-9]-?[^SLOIBZsloibz0-9][^SLOIBZsloibz][0-9]-?[^SLOIBZsloibz0-9][^SLOIBZsloibz0-9][0-9][0-9]$/m';
$str = '1EG4-TE5-MK73
1EG4TE5MK73
1SG4-TE5-MK73
0EG4-TE5-MK73
9q57xg8ed35
';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php