Check address

[Anon]

how to check the address in the location bar?
i.e. http://www.domain.com?id=454hd&session=sjfdj7&place=ny.

How to check whether a particular one is empty? If a viewer manipulates and leaves 'id' blank,then it goes to another page. How to do that?
Thanks in advance

[[deleted]]

http://www.php.net/manual/en/language.variables.predefined.php

look for HTTP_GET_VARS and HTTP_POST_VARS