CodeIgniter Parameter in middle of route - php

Question

I'm currently learning codeigniter but I'm having a bit of an issue with routing. My routes file is as below:
<?php
defined('BASEPATH') OR exit('No direct script access allowed');
$route['images/(:num)/upload/'] = 'image/upload/$1';
$route['images/(:num)'] = 'image/index/$1';
$route['yoyo/(:num)'] = 'yoyo/view/$1';
$route['default_controller'] = 'yoyo';
$route['404_override'] = '';
$route['translate_uri_dashes'] = FALSE;
My issue is with the first route; I'm unable to get it to work without moving (:num) to the end of the route. Based on other routes I've seen after browsing stackoverflow it get the impression that this should work. Any ideas?
So just to be clear it works if I add the follow route instead:
$route['images/upload/(:num)/'] = 'image/upload/$1';

Answer 1

$route['images/(:num)/upload/'] = 'image/$1/upload';
Edit: What was I thinking..sorry.
Of course you can't do the code I told you, because the route images/$1/upload means that you will access the controller images ...and the function $1.
Obviously, you can't do that. This is what you should do:
$route['images/upload/(:num)'] = 'image/upload/$1';
public class image extends CI_Controller
{
public function upload($arg0) {}
}
And then if you want to pass more args, you just need to continue the route path.
$route['images/upload/(:num)/(:any)'] = 'image/upload/$1/$2';
public function upload($arg0, $arg1) {}