PHP Function To Convert IP Address to IP Number

function Dot2LongIP ($IPaddr)
{
    if ($IPaddr == "") {
        return 0;
    } else {
        $ips = split ("\.", "$IPaddr");
        return ($ips[3] + $ips[2] * 256 + $ips[1] * 256 * 256 + $ips[0] * 256 * 256 * 256);
    }
}