Problem with Macros

Question

HI ,

Can some one help me in understanding why the value of SQUARE(x) is 49 ?

I am using Visual C++ 6.0 .

#define SQUARE(X) X * X

int main(i         


        

Answer 1

Because the macro expands to:

++y * ++y

which gives undefined behaviour in C++ - the result could be anything. This very well known problem should be covered in any decent textbook that covers the use of macros. Which one are you using?