$re = '/^((\d{1,2}(,\d{3})+)|(\d+)(\.\d{2})?)$/m';
$str = '10000000
10,000,000
10000000.00
10,000,000.00';
preg_match_all($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