Base10 to base64 url shortening

Question

I\'m coding an url shortener function for a project in which I\'m learning php, here is the code (btw I suppose that global here is not a good thing to do :P):<

Answer 1

How about this:

function shorten_int($id){
    $hex = base_convert(id, 10, 16);
    $base64 = base64_encode(pack('H*', $hex));
    //$base64 = str_replace("/", "_", $base64); // remove unsafe url chars
    //$base64 = str_replace("+", "-", $base64);
    //$base64 = rtrim($base64, '='); // Remove the padding "=="
    $replacePairs = array('/' => '_',
                          '+' => '-',
                          '=' => '');
    $base64 = strtr($base64, $replacePairs); // optimisation
    return $base64;
}