$re = '/\d{4,5}-\d{2,3}|\w{3}\d-\d{2}|\d{4,5}-\w{1}\d{2}|\b|\d{4}-\w\d{1}\w|\d{4,9}/';
$str = '11111-C00';
preg_match($re, $str, $matches, PREG_OFFSET_CAPTURE, 0);
// Print the entire match result
var_dump($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