$re = '/\b(?:\d{2}[-.\s]?){5}\b/m';
$str = '0231000000
02 31 00 00 00
02.31.00.00.00
02-31-00-00-00
0231123456789
02:31:00:00:00';
preg_match_all($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