Passing arrays as url parameter

What is the best way that I can pass an array as a url parameter? I was thinking if this is possible:

$aValues = array();

$url = 'http://www.example.com?aParam='.$aValues;

or how about this:

$url = 'http://www.example.com?aParam[]='.$aValues;

Ive read examples, but I find it messy:

$url = 'http://www.example.com?aParam[]=value1&aParam[]=value2&aParam[]=value3';

Answer

There is a very simple solution: http_build_query(). It takes your query parameters as an associative array:

$data = array(
    1,
    4,
    'a' => 'b',
    'c' => 'd'
);
$query = http_build_query(array('aParam' => $data));

will return

string(63) "aParam%5B0%5D=1&aParam%5B1%5D=4&aParam%5Ba%5D=b&aParam%5Bc%5D=d"

http_build_query() handles all the necessary escaping for you (%5B => [ and %5D => ]), so this string is equal to aParam[0]=1&aParam[1]=4&aParam[a]=b&aParam[c]=d.