$re = '/^([1-9][1-9][1-9]\d{2}\d*|[1-9][2-9]\d{3}\d*|[2-9]\d{4}\d*|\d{6}\d*)$/m';
$str = '1
12
100
101
102
999
444
333
9999
10001
10000
10930
10903
11022
11014
11099
11100
12011
20000
30000
11111
11562
11234
12453
22222
232312
200000
2000000
123123213
12321324343432434';
preg_match_all($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