#include <iostream>

// the ## preprocessing operator joins 2 preprocessing tokens and then that token is reevaluated
// see 16.3.3

#define MACONE(x,y) x
#define MACTWO(x,y) y
#define PICK(picker, x, y) MAC ## picker (x,y)

int main(int argc, char** argv)
{
  // prints 5
  std::cout << PICK(ONE, 5, 7) << std::endl;

  // prints 7
  std::cout << PICK(TWO, 5, 7) << std::endl;

  return 0;
}