How to pass multiple parameters from url in Codeigniter?

Question

I am newbie. How to pass multiple parameters from URL in codeigniter? My function showing ads in a given category

    public function show_category($category = false, $subcategory = false, $state = false, $city = false)
{
   // Showing ads...
}

I would like my urls to look like this

localhost/show_category/category/subcategory/state/city

But what if one of the parameters is not given? How to make category not mistaken for a city when I pass only two parameters?

localhost/show_category/category/city

Answer 1

Considering it for SEO purpose, I think it would be safe to leave just the category and the subcategory in the url, and leave the rest as GET variable:

public function show_category($category = false, $subcategory = false)
{
    $state = $_GET['state'];
    $city = $_GET['city'];
   // Showing ads...
}

then you can skip the category and subcategory url segment, and send the state and city as query string:

localhost/show_category/category/subcategory?state=x&city=y