c++ precompiler booleans

A short post to show you some of the possible precompiler if booleans you can write. I had to learn how to place several define requirements in one #if statement. Here you go:

#include <iostream>

#define M1

#define M2

using namespace std;

int main()

{

#ifdef M1

      cout << “M1 defined!” << endl;

#endif

#ifdef M2

      cout << “M2 defined!” << endl;

#endif

#ifndef M3

      cout << “M3 not defined!” << endl;

#endif

#ifdef M4

      cout << “M4 defined!” << endl;

#endif

#if defined(M1) && defined(M4)

      cout << “M1 and M4 defined!” << endl;

#endif

#if defined M2 || defined M3

      cout << “M2 or M3 defined!” << endl;

#endif

#if ! defined M3 && ! defined M4

      cout << “neither M3 nor M4 defined!” << endl;

#endif

#if ! defined(M3) && defined M2

      cout << “M3 not defined, M2 defined!” << endl;

#endif

      return 0;

}

This code shows most options I know of. The output is (in case you are too lazy to check..):

M1 defined!

M2 defined!

M3 not defined!

M2 or M3 defined!

neither M3 nor M4 defined!

M3 not defined, M2 defined!

 

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