$re = '~^(?=(?:[^\n\d]*\d){4})[-0-9_,/\s]+$~m';
$str = '1,2
3/5/6
7-8-9
09-12345678
123, 456, 789
12/ 34/ 56
';
preg_match_all($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