Rpp is a project mainly written in C++ and C, it's free.
C++ preprocessor
Roberto Raggi's C++ parser
Obtained from the qtjambi-gpl-src-4.3.0_01.tar.gz package
To Build: qmake -recursive make
look in the examples directory for a simple example
./example foo.cpp (just outputs any found classes and its functions) ./example -E foo.cpp (outputs the preprocessed file)