GCC System Headers

["Eddie Diener" <eddielee@xxxxxxxxxxxxxx>]

How does GCC/G++ know where to look for its system header files ?

I am using GCC/G++ with MingW/DevCpp on Windows. In the DevCpp distribution,
which used GCC 3.2.3, the C header files are in the DevCpp\include directory
and the C++ header files are off of the DevCpp\include\c++ directory. Yet
when I downloaded the latest MingW/GCC/G++ implementation, 3.3.1, there are
no C header files in the release and the C++ header files are placed off of
the DevCpp\include\c++\3.3.1 directory.

So I am confused. First, why there are no C header files in the
distribution, and secondly how GCC/G++ knows where to find its system header
files.