#include <iostream>
#include <cstdlib>
using namespace std;

#define SWAP(T, a, b)   {const T temp = (a); (a) = (b); (b) = temp;}

int main()
{
	int i = 10;
	int j = 20;
	SWAP(int, i, j);           //will compile
	cout << "i == " << i << ", j == " << j << "\n";

	int temp = 30;
	//SWAP(int, i, temp);      //won't compile

	size_t a[] = {10, 20, 30};
	size_t k = 2;
	SWAP(size_t, k, a[k]);     //undefined behavior
	cout << "k == " << k << ", a[2] == " << a[2] << "\n";

	const bool b = true;
	int x = 10, y = 20, z = 30;
	SWAP(int, b ? x : y, z);   //swap x and z
	cout << "x == " << x << ", y == " << y << ", z == " << z << "\n";

	return EXIT_SUCCESS;
}