C++ increment with macro

Asked May 07 '22 at 06:21

Active May 07 '22 at 06:21

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-2

I have the following code and I want to use increment with macro:

#include <iostream>

#define ABS(x) ((x) < 0 ? -(x) : (x))

int main(int argc, char** argv)
{
    int x = 5;
    const int result = ABS(x++);

    std::cout << "R: " << result << std::endl;
    std::cout << "X: " << x << std::endl;

    return EXIT_SUCCESS;
}

But output will be incorrect:

R: 6
X: 7

Is it possible to somehow use macros with an increment, or should this be abandoned altogether?

edited May 07 '22 at 06:21

kaylum

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asked May 07 '22 at 06:21

QuickDzen

1

What do you expect the result to be? You should note that every `x` in the macro is replaced by `x++`. That is, `x` will always be incremented twice. – kaylum May 07 '22 at 06:24
2

Yes, it's possible (not with *that* macro), and still, It should be abandoned altogether. – WhozCraig May 07 '22 at 06:24
Why not use a templated function ? – wohlstad May 07 '22 at 06:26
Or try `std::abs`? – BoP May 07 '22 at 09:36

C++ increment with macro

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