Function-like macros and strange behavior

Question

I have started reading Effective C++ and at some point in item 2, the following is mentioned:

// call f with the maximum of a and b
#define CALL_WITH_MAX(a,          


        

Answer 1

Use g++ -E myprog.cpp (replace g++ with whatever-your-compiler-is if you are not using g++) - it works on ALMOST all compilers, it will produce the actual stuff after preprocessing.

And this is a great example of why you shouldn't use macros to do function-type stuff.

You'd get much more of what you (probably) expect if you were to use an inline function:

 inline void CallWithMax(int a, int b) 
 {
     f((a) > (b) ? (a) : (b));
 }

Any decent compiler should be able to do this AT LEAST as efficient as a macro, with the added advantage that your a and b are evaluated once in the calling code, and nothing "weird" happens.

You can also step through a inline function if you build your code with debug symbols, so if you want to see what value a and b actually are inside the function, you can do that. Macros, because they expand into the original place in the source code, so you can't really see what's going on inside.