System header files usually employ platform-specific extensions not only on the preprocessor side, but in preprocessed code as well AFAIK. That is, the compiler

System header files usually employ platform-specific extensions not only on the preprocessor side, but in preprocessed code as well AFAIK. That is, the compiler has to support them too. My comment was not to say that coding cpp is easy - just that it's not a particularly hard task compared to the compiler itself.