How to apply a C preprocessor only to certain (#if/#endif) directives?

Question

I was wondering if it is possible, and if yes how, can I run a C preprocessor, like cpp, on a C++ source file and only process the conditional directives #

Answer 1

The linux unifdef command does what you want:

http://linux.die.net/man/1/unifdef

Even if you're not on linux, there is source available on the web.

BTW, this is a duplicate of another question: Way to omit undefined preprocessor branches by default with unifdef?