Default include directories

[Miguel Guedes]

Hello list,

In order to find out what the system include directories are, I can run 
`cpp -v </dev/null' or compile a test program with GCC (i.e. gcc -v 
test.c). This works fine but unfortunately I'm in need of a programmatic 
way of finding out what the system include directories are without 
resorting to launching external programs.

Anyone knows how GCC determines the directories?