What problems might the following macro bring to the application?

Question

Can the following macro bring problems?

#define sq(x) x*x

If yes, then how and why?please help.

Answer 1

Yes, it can present problems. Other than the obvious fact that macros don't respect namespaces at all (which means you can't call anything else sq), try the following:

int result = sq(4) / sq(4);

You should surround x * x with parenthesis so it becomes ((x) * (x)).

Another problem:

int a = 0;
int result = sq(++a);

This is an inherent problem with macros, and is one reason inline functions should be preferred.