How does this code work?

[cgchris99]

My question is how it works

if ($ref) {
$advertiser = $HTTP_GET_VARS["ref"];
if ($advertiser){
tep_session_register('advertiser');
}
}

This code is for oscommerce if that matters at all.

How does the $ref not be empty the first time this code runs?
Does PHP somehow know it is part of the URL ?ref=referallnamehere

Thanks for any advice at all as to how the if ($ref) doesn't fail when this code runs.

[yelvington]

Originally posted by cgchris99

How does the $ref not be empty the first time this code runs?

From the code fragment you posted, it doesn't ... unless register_globals is turned on (which is NOT a good thing) and a value is passed in a GET, POST or COOKIE.