C/C++ #define Macro inside macro?

Question

I would like something like:

#define C_OR_CPP(C__, CPP__) #ifdef __cplusplus\\
CPP__\\
#else\\
C__\\
#endif

Is it possible? Maybe some dirt

Answer 1

What's the problem with

#ifdef __cplusplus
#define C_OR_CPP(C, CPP) CPP
#else
#define C_OR_CPP(C, CPP) C
#endif

(Leaving names with double underscore to the implementation per phresnel remark)