Calling a C++ macro with fewer arguments

Question

Hi,

is it possible to call function-like-macros with less that all the parameters in linux? actually doing this only generates a warning in Visual Studio (warning 4003) and unassigned variables replaces with "".

But compiling it using g++ generates an error in linux ("error: macro * requires ** arguments, but only ** given").

is there any possible way to disable this or overcome it?

Answer 1

The number of arguments in a macro invocation must exactly match the number of parameters in the macro definition. So, no, you cannot invoke a macro with fewer arguments than it has parameters.

To "overcome" it, you can define multiple differently named macros with different numbers of parameters.

C++0x (which is not yet standard, but which your compiler might partially support) adds support for variadic macros which can be called with a variable number of arguments.

Answer 2

The standard (§16.3 - Macro replacement) is clear that you have to pass the same number of arguments:

"If the identifier-list in the macro definition does not end with an ellipsis, the number of arguments (including those arguments consisting of no preprocessing tokens) in an invocation of a function-like macro shall equal the number of parameters in the macro definition."

I don't know of any g++ option to override this.