How to grab URL parameters using PHP?

Question

I'm trying to grab each URL parameter and display them from first to last, but I want to be able to display any of the parameters anywhere on the page. How can I do this? What do I have to add or modify on my script?

Here is an example of a URL value.

http://www.localhost.com/topics/index.php?cat=3&sub1=sub-1&sub2=sub-2&sub3=sub-3&sub4=sub-4

Here is my PHP script.

$url = $_SERVER['QUERY_STRING'];
$query = array();

if(!empty($url)){
  foreach(explode('&', $url) as $part){
    list($key, $value) = explode('=', $part, 2);
    $query[$key] = $value;
  }
}

Answer 1

You don't need to do that manually, PHP already provides this functionality in the $_GET global variable:

<?php
    foreach($_GET as $key => $value)
        echo $key . " : " . $value;
?>