$re = '/((\d{4}-\D{3})|(\D{3} - \d{4} and earlier))/m';
$str = '2021-SMC
2022-SSC
SMC - 2020 and earlier
SSC - 2021 and earlier
2021 - SMC_copy
2022 - SMC_1';
preg_match_all($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