// CS2 Chung, Operator Overloading (II)
// Overlaoding Output and Input Operators. 
// Goal: cin >> p1; cout << p2;
#include <iostream.h>
class Point
{
   private:
      double x;
      double y;
   public:
      Point() { x = 0; y = 0; }
      Point(double init_x, double init_y)
      {  x = init_x;
         y = init_y;
      }
      friend istream& operator >> (istream& ins, Point& target)
      {
         cout << "Enter x and y for a point: ";
         ins >> target.x >> target.y;
         return ins;
      }
      friend /* ostream& */ void operator << (ostream& outs, Point& source)
      {
         outs << "(" << source.x << ", ";
         outs << source.y << ")" << endl;
         // return outs;
      }
      friend  bool operator == (const Point& p1, const Point& p2);
      friend  Point operator + (const Point& p1, const Point& p2);
};


bool operator == (const Point& p1, const Point& p2)
{
   return ((p1.x == p2.x) && (p1.y == p2.y));
}

Point operator + (const Point& p1, const Point& p2)
{
   double x_sum, y_sum;
   x_sum = p1.x + p2.x;
   y_sum = p1.y + p2.y;
   Point sum(x_sum, y_sum);
   return sum;
}

void main()
{
   Point p1, p2;
   cin >> p1 >> p2;
   // cout << p1 << p2;  Compile error! No cascading output op.
   cout << "1st point: " << p1;
   cout << "2nd point: " << p2;
   if(p1 == p2)
      cout << "Those points are equal." << endl;
   else
      cout << "Those points are NOT equal." << endl;
   Point p3(p1+p2);
   cout << p3;
   Point p4 = p1 + p2; // This works!
   cout << p4;
}