$re = '/(\d{2}(\d{2})?\/\d{2}\/\d{2}(\d{2})?)|(\d{2}:\d{2}(:\d{2})?)/';
$str = '----------17/01/01----------00:00:00-----
-----17/02/02 09:03----------------------
--------------------34:23----------------
-----17/02/04 11:09:24-------------------
------------------17/04/27---------------
-----------------------------------------
';
preg_match_all($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