setuid() and getenv()?

From: vertigo (none_at_microsoft.com)
Date: 07/16/04 

Date: Fri, 16 Jul 2004 15:59:10 +0200

Hello
i need to read $PATH variable for all users.
I wanted to use something like setuid() and getenv() in C.
Are there similar functions here ?
(if not how can i do it ?)

Thanx
Michal