public function signup_validation()
{
    $this ->load->library('form_validation');

    $this->form_validation->set_rules('username', 'Username', 'required|trim|is_unique[userinfo.username]|strtolower');
    $this->form_validation->set_rules('password', 'Password', 'required|trim');
    $this->form_validation->set_rules('cpassword', 'Confirm Password', 'required|trim|matches[password]');

    $this->form_validation->set_message('is_unique', 'That Username Already Exists.');

    if($this->form_validation->run()){
    }else{
        $this->load->view('signup');
    }
}