Macros in macros (C++)

Question

Is it possible to put a macro in a macro in c++?

Something like:

#define Something\
#ifdef SomethingElse\ //do stuff \
#endif\

I tried and it didn't work so my guess is it doesn't work, unless there's some sort of syntax that can fix it?

Answer 1

No, but you can simply refactor this by pulling the #ifdef out as the toplevel, and using two different #define Something ... versions for the true and false branches of the #ifdef.

Answer 2

Macros, yes. Preprocessor directives, which are what you posted, no

Answer 3

No. I answered this in http://stackoverflow.com/questions/2506167/c-macros-with-memory

If you want to inspect or alter the preprocessing environment, in other words to define a preprocessing subroutine rather than a string-replacement macro, you need to use a header, although the legitimate reasons for doing so are few and far between.