PHP Undefined Index

I have this code and it's giving me an undefined error if country is not a variable in the URL. I've never had this problem before so it's obviously something to do with server settings but I'd rather not change those because this is probably done for security purposes. I've searched Google and can't find the workaround, although I'm sure it's blindingly obvious!

$country = $_GET['country'];

    if(!$country){
        $incoming = $outgoing = $sms = $free = "---";
    } else {
        get_rates($country);
    }

Answer

you should use the following approach:

if (!isset($_GET['country'])) {
    $incoming = $outgoing = $sms = $free = "---";
} else {
    get_rates($_GET['country']);
}