问题
I need to write a variadic macro in C which must take zero or more arguments.
In gcc, that can be achieved by adding "##" after the comma, e.g. ,##____VA_ARGS____ as answered in Variadic macros with zero arguments.
However, the compiler in my build system (beyond my control) does not understand the ,## syntax and so does not swallow the comma.
Is there a workaround I can use?
Thanks!
回答1:
Yes, gcc swallowing the comma is non standard and you should not rely on that.
With C99 conforming preprocessors you may achieve a similar effect by testing for a macro arguments that is the empty token. For the ideas of how this works you could see here, for a whole set of preprocessor macros that ease the programming of such features there is P99.
来源：https://stackoverflow.com/questions/8444698/swallowing-comma-in-variadic-macros-on-compilers-that-do-not-recognise