How do I check if one of multiple macros is defined in a single #ifdef?

问题

I have some C++ code, and want to perform an action if the __APPLE__ or __linux macros are defined.

If I did it as a normal if conditional, it would be easy using ||:

if (something || something) { .. code .. }

But as of what I know there is no || operator for #ifdef statements. How would I check if __APPLE__ or __linux is defined using a single #ifdef statement?

回答1:

You can't in a single #ifdef would a single #if do instead?

#if defined(__APPLE__) || defined(__linux)

this also works if you prefer

#if defined __APPLE__ || defined __linux

回答2:

In my C++ there is.

#if defined(__APPLE__) || defined(__linux)
  // ...
#endif

来源：https://stackoverflow.com/questions/16378734/how-do-i-check-if-one-of-multiple-macros-is-defined-in-a-single-ifdef