$re = '/^(?:(?:(?<three>\d+),)?(?<two>\d+),)?(?<one>\d+)$/m';
$str = '1,4,34
5,15
22
1,2,3
11,12
11,12,13
1,2
1
,1,2,3
,1,2
,1
,
1234
1,234
1234,123
1,2
111,222
111,2,4444
11,22
12345,12345,12345
12345,12345,12345,12345
,,
1,
1,2,';
preg_match_all($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