How to set a value into a cookie or session in Drupal

I am working on a friend reference function, so I pass the user id through the url like this:

www.example.com?fid=22

I need to set this as a session o开发者_如何学运维r cookie with access to all modules in Drupal 6.

If i set the session it returns for the particular module. Setting the cookie is not working at all.

$user->new_property works only on the particular page where it is set, if I move to another page there is no new_property in $user variable object list.

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If you want to save a variable in a users session, you can in Drupal (PHP) use the super global varaible $_SESSION.

$_SESSION['fid'] = $_GET['fid'];

The above code is an example of how this could be done.

Since you are getting the info from the URL the user can change it as his whim. So be careful what you use such data for and never trust it blindly. It could become anything, as the user always freely can alter the url any way he want.