#include <iostream>

using namespace std;

class Point {

 private:
   int x, y;
 
 public:
  Point() {}
  Point(int px, int py) {
    x = px;
    y = py;
  }

  void show() {
    cout << x << " ";
    cout << y << endl;
  }

  Point operator+(Point op2);
  Point operator-(Point op2);
  Point operator=(Point op2);
  Point operator++();
  
};

// Overload + for Point.
Point Point::operator+(Point op2)
{
  Point temp;

  temp.x = op2.x + x;
  temp.y = op2.y + y;

  return temp;
}

// Overload - for Point.
Point Point::operator-(Point op2)
{
  Point temp;

  // notice order of operands
  temp.x = x - op2.x;
  temp.y = y - op2.y;

  return temp;
}

// Overload asignment for Point.
Point Point::operator=(Point op2)
{
  x = op2.x;
  y = op2.y;

  return *this; // i.e., return object that generated the call
}

// Overload prefix ++ for Point.
Point Point::operator++()
{
  x++;
  y++;

  return *this;
}

int main()
{
  Point ob1(1, 2), ob2(3, 4), ob3(5, 6);

  ob1.show(); // displays 1 2
  ob2.show(); // displays 3 4
  cout << endl;

  ++ob1;
  ob1.show(); // displays 2 3
  cout << endl;

  ob2 = ++ob1;
  ob1.show(); // displays 3 4
  ob2.show(); // displays 3 4
  cout << endl;

  ob1 = ob2 = ob3; // multiple assignment
  ob1.show(); // displays 5 6
  ob2.show(); // displays 5 6

  getchar();
  return 0;
}