CodeIgniter user profile controller

Why isn't this working? I'm trying to make a php user profile URL.

<?php
class Users extends Controller {
  function Users() {
    parent::Controller();
  }
  function index($id == null) {
    if($id == null) {      
      redirect('/', 'refresh');      
    }
    else {
      $data['title']  = 'User Page';
      $data['result'] = $this->users_model->get_all_data();
      $data['userid'] = $id; // in the view, you can u开发者_如何学JAVAse $userid as a variable
      $this->load->view('users',$data);
    }
  }
}
?>

Parse error: parse error, expecting `')'' in C:\wamp\www\system\application\controllers\users.php on line 7

You probably meant to give $id a default value of null using the = assignment operator, like this:

function index($id = null) {

Your posted code uses the == equality operator in the function declaration, which is a syntax error.

I don't think you can have the index page take any parameters, I've tried it before (if you do that, it will be accessible at example.com/user/index/5, but not example.com/user/5. I would put all that code in another function called profile. Or you can try what some suggest on this forum post:

http://codeigniter.com/forums/viewthread/94028/

Hope this helps!