Preprocessor equality test, is this standard?

Question

I had envisaged one of these in the project preferences

• TESTING = HOST
• TESTING = TARGET

Answer 1

And note that you can do this:

#ifndef TESTING
    ...
#elif TESTING == HOST
    ...
#elif TESTING == TARGET
    ...
#else
    #error "Unexpected value of TESTING."
#endif

Also:

#if defined(TESTING) && TESTING == HOST
    ...
#endif

If you want to collapse the tests. The parenthesis are optional (#if defined TESTING is valid) but I think it's clearer to include them, especially when you start adding additional logic.