Is there a nicer way to get the data from registration form?

Is there a way to get the data from an registration form by counting the inputs and textfields but excluding the submit and hidden ones? Lets say I have a form with 5 input fields that contains the data for registration can I make an array for all so when I process the data instead of:

interface userAction {
    public function login();
    public function logout();
    public function isActive();
    **public function addUser($first_name, $last_name, $email, $password, $username, $company_name, $company_address, $zip_code, $city, $country, $phone, $uid, $userIP, $user_level);**
}

I can do: public function addUser($data); <- $data is assoc array