#include <iostream>
using namespace std;

int main()
{
  void swap(int& x, int& y); // void swap(int &x, int &y); also works
  int a = 1, b = 2;
  cout << "a = " << a << " b = " << b << endl;
  swap(a,b);
  cout << "a = " << a << " b = " << b << endl;
  return 0;
}

void swap(int&x, int& y)
{
  int temp;
  temp = x;
  x = y;
  y = temp;
}