$re = '/^(?:31([-\/.\x20])(?:0?[13578]|1[02])\1|(?:29|30)([-\/])(?:0?[13-9]|1[0-2])\2)(?:1[6-9]|[2-9]\d)?\d{2}$|^29([-\/])0?2\3(?:(?:1[6-9]|[2-9]\d)?(?:0[48]|[2468][048]|[13579][26])|(?:16|[2468][048]|[3579][26])00)$|^(?:0?[1-9]|1\d|2[0-8])([-\/])(?:0?[1-9]|1[0-2])\4(?:1[6-9]|[2-9]\d)?\d{2}$/m';
$str = '30/,/1601
20/01/2011
19/09/2017
20/01/1601
28/,/1600';
preg_match_all($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