$re = '/(\d{4}-\d{2}-\d{2})(\s|T|t)(\d{2}:\d{2}(?::\d{2})?)?/';
$str = '2016-02-01
2016-02-01 00:00
2016-02-01T00:00
2016-11-10 12:30:11
2016-02-01T12:30:11
';
preg_match_all($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