How the macro func and function func can be distinguished without any ambiguity?

Question

#include<iostream>
int func(int, int);
#define func(x,y) x/y+x
int main()
{
    int i, j;

    scanf("%d", &i);
    scanf("%d", &j);

    printf("%d ", func(i + j, 3));
    printf("%d\n", func(i + j, 3));

}

int func(int x, int y) {
    return y / x + y;
}

What should be added to this code so that the 1st output is the result of the macro and the 2nd one is the result of the function?

Answer 1

Several ways:

printf("%d ", func(i + j, 3)); // Macro call
#undef func // Macro is no longer defined
printf("%d\n", func(i + j, 3)); // Function call

or

printf("%d ", func(i + j, 3)); // Macro call
printf("%d\n", (func)(i + j, 3)); // Function call

Answer 2

Yet another way:

#define EMPTY

printf("%d\n", func EMPTY (i + j, 3));

Seen in Boost.PP, the EMPTY macro "burns up" the expansion iteration and the resulting func(...) is left untouched.