How to make G++ preprocessor output a newline in a macro?

Question

Is there a way in gcc/g++ 4.* to write a macro that expands into several lines?

The following code:

#define A X \\ Y

Expands into

Answer 1

You can just put a magic character sequence in the macro, e.g.

#define X(y,z) y nl z

run gcc -E infile | sed g/s/nl/\n/ > whatever

(Maybe not exactly right, but you get the idea, right? Pipe it through sed or tr or run Emacs on the output.)

I do this sometimes to use C macros to generate source code and no I don't want to learn how to do it in Perl or M4 or yet another tool.