User Registration and Form Validation Using CodeIgniter

//validate form input
$this->form_validation->set_rules('guest_title', 'Title', 'required|xss_clean');
$this->form_validation->set_rules('first_name', 'First Name', 'required|xss_clean');
$this->form_validation->set_rules('last_name', 'Last Name', 'required|xss_clean');
$this->form_validation->set_rules('birth_date_year', 'Year', 'xss_clean');
$this->form_validation->set_rules('birth_date__nc_month', 'Month', 'xss_clean');
$this->form_validation->set_rules('birth_date__nc_day', 'Day', 'xss_clean');
$this->form_validation->set_rules('company', 'Company', 'xss_clean');
$this->form_validation->set_rules('url', 'Website', 'xss_clean');
$this->form_validation->set_rules('address', 'Address', 'required|xss_clean');
$this->form_validation->set_rules('address_2', 'Address 2', 'xss_clean');
$this->form_validation->set_rules('city', 'City', 'required|xss_clean');
$this->form_validation->set_rules('state', 'State/Province', 'xss_clean');
$this->form_validation->set_rules('country', 'Country', 'required|xss_clean');
$this->form_validation->set_rules('zipcode', 'Zip/Postal code', 'required|xss_clean');
$this->form_validation->set_rules('phone', 'Phone', 'required|xss_clean');
$this->form_validation->set_rules('email', 'Email Address', 'required|valid_email');
$this->form_validation->set_rules('username', 'Username', 'required|xss_clean');
 
$this->form_validation->set_rules('password', 'Password', 'required|matches[password_confirm]');
$this->form_validation->set_rules('password_confirm', 'Password Confirmation', 'required');