$re = '/^(?:(0[1-9]|[1-9][0-9])0{6}|(0[1-9]|[1-9][0-9]){2}0{4}|((?:0[1-9]|[1-9][0-9])){3}00|(?:0[1-9]|[1-9][0-9]){4})$/m';
$str = '00000000
01000000
10000000
10440044
99990000
99999900
99000099
77007788
55555555';
preg_match_all($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