I do not understand the behaviour of #define macro in C++

Question

I need to understand how this code works:

#define foo1( a ) (a * a)              // How does this work?
inline int foo2(         


        

Answer 1

Macro is not a function. The compiler will expand all macros and then compile it. To see the expanded code, you can use the following command using -E option in gcc:

gcc -E  -o 

Or in Visual C++, under Configuration Properties->C/C++->Preprocessor, set "Generate Preprocessed File".

BTW, your macro is problematic. You should use

#define foo1( a ) ((a) * (a))

instead of

 #define foo1( a ) (a * a)