$re = '/(?:(?:(?:0*(\d+)d\s)?0*(\d+)h\s)?0*(\d+)m\s)?0*(\d+)s/m';
$str = '98d 01h 23m 45s
01d 02h 03m 04s
02h 03m 04s
03m 04s
04s';
preg_match_all($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