How do I implement no-op macro (or template) in C++?

Question

How do I implement no-op macro in C++?

#include    

#ifdef NOOP       
    #define conditional_noop(x) what goes here?   
#else       
    #         


        

Answer 1

Like others have said, leave it blank.

A trick you should use is to add (void)0 to the macro, forcing users to add a semicolon after it:

#ifdef NOOP       
    #define conditional_noop(x) (void)0
#else       
    #define conditional_noop(x) std::cout << (x); (void)0
#endif  

In C++, (void)0 does nothing. This article explains other not-as-good options, as well as the rationale behind them.