System Headers Path?

Is there an environment variable or other mechanism whereby I can get the system headers path? Preferrably I would like to be able to gather this information independant of the flavor of Unix. Thanks, Scott.

To my knowledge, there is no standard cross-platform location for all system include files. This is one of the reasons that when you compile code you type a setup utility (normally ./configure) in the root directory of the distribution. The configure script has conditional code that tests for version, installed libs, installed utilities, headers and the locations (paths). This information is used to create a platform specific Makefile.