$re = '/\((?=.{0,10}\))([^)]+)\)/m';
$str = '(some text) some other text -> some text
(some) some other text -> some
(12345) some other text -> 12345
(TooLongStri) -> nothing matched because 11 characters';
preg_match_all($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