Retrive paramater from url in ci-3

http://localhost/codeigniter/ci3/index?id=3  (url)

public function index()  (controller)
{
$id = $_GET['id'];
echo $id; die();
$arr['data'] = $this->WelcomeModel->index();
$this->load->view('pages/home', $arr);
}

http://localhost/codeigniter/ci3/index/4

public function index($id = 3, $name = 'homepage')
{
echo $id.' '.$name; die();
$arr['data'] = $this->WelcomeModel->index();
$this->load->view('pages/home', $arr);
}