[Solved] Macros in C++ breaks with postfix increments

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You can’t use this macro outside of a function, because it’s an arbitrary expression, that’s why you’re getting an error.

Just move the invocation of the macro into function scope and it will work:

#define MAX(x, y, r) ((x) > (y) ? (r = x) : (r = y))

int x = 10;
int y = 20;
int r;

int main()
{
    MAX(x, y, r);
}

Using macros in this case is, however, unnecessary (unless this is just an exercise to learn macro usage); making max a function (or, better yet, using std::max) would be a better and less error-prone way.

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solved Macros in C++ breaks with postfix increments