Check the parse_string
function http://php.net/manual/en/function.parse-str.php
It will return all the variables from a query string, including arrays.
Example from php.net:
<?php
$str = "first=value&arr[]=foo+bar&arr[]=baz";
parse_str($str);
echo $first; // value
echo $arr[0]; // foo bar
echo $arr[1]; // baz
parse_str($str, $output);
echo $output['first']; // value
echo $output['arr'][0]; // foo bar
echo $output['arr'][1]; // baz
?>