public static function createMobileToken($length = 6) { $randomString = ''; $characters = '0123456789'; $charactersLength = strlen($characters); for ($i = 0; $i < $length; $i++) { $randomString .= $characters[rand(0, $charactersLength - 1)]; } return $randomString; }
「解說」
strlen :回傳字串長度。