$re = '/(\d+[x]\d+\w)([a-e])|(\d+[x]\w+)|\bS(?P<Season>\d+)E(?P<Episode>\d+)|(\b[s]\d+[e]\d+)([a-e])/m';
$str = '02x01
03x02a
S03E01
s03e01a
03x02xxxxxxxxxx
s03e01xxxxxxxxx';
preg_match_all($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