#include <iostream>
using namespace std;
// Point类
class Point
{
  // 构造函数与析构函数
  public:
    Point(int _x = 0, int _y = 0) : x(_x), y(_y){}
    ~Point(){}
  // 普通成员函数
  public:
    // 输出点的坐标
    void showPosition(){cout << "(" << x << ", " << y << ")" << endl;}
  // 运算符函数重载
  public:
    // 前置， ++i\--i
    Point operator ++();
    Point operator --();
    // 后置,i++\i--
    Point operator ++(int);
    Point operator --(int);
  private:
    int x;
    int y;
};
Point Point::operator ++()
{
  Point po;
  po.x = x + 1;
  po.y = y + 1;
  x += 1;
  y += 1;
  return po;
}
Point Point::operator --()
{
  Point po;
  po.x = x - 1;
  po.y = y - 1;
  x -= 1;
  y -= 1;
  return po;
}
Point Point::operator ++(int)
{
  Point po;
  po.x = x;
  po.y = y;
  x += 1;
  y += 1;
  return po;
}
Point Point::operator --(int)
{
  Point po;
  po.x = x;
  po.y = y;
  x -= 1;
  y -= 1;
  return po;
}
int main()
{
  Point po(0, 0);
  Point po1(2, 3);
  Point po2(1, 4);
  // 三点初始坐标
  cout << "Position po: "; po.showPosition();
  cout << "Position po1: "; po1.showPosition();
  cout << "Position po2: "; po2.showPosition();
  cout << "_______________" << endl;
  // 后置运算后的坐标
  po = po1++;
  cout << "Pos ++: po = "; po.showPosition();
  cout << "Pos ++: po1 = "; po1.showPosition();
  po = po2--;
  cout << "Pos --: po = "; po.showPosition();
  cout << "Pos --: po2 = "; po2.showPosition();
  cout << "_______________" << endl;
  // 前置运算后的坐标
  po = ++po1;
  cout << "Pre ++: po = "; po.showPosition();
  cout << "Pre ++: po1 = "; po1.showPosition();
  po = --po2;
  cout << "Pre --: po = "; po.showPosition();
  cout << "Pre --: po2 = "; po2.showPosition();
  return 0;
}

Position po: (0, 0)
Position po1: (2, 3)
Position po2: (1, 4)
_______________
# po = po1++;
Pos ++: po = (2, 3)
Pos ++: po1 = (3, 4)
# po = po2--;
Pos --: po = (1, 4)
Pos --: po2 = (0, 3)
_______________
# po = ++po1;
Pre ++: po = (4, 5)
Pre ++: po1 = (4, 5)
# po = --po2;
Pre --: po = (-1, 2)
Pre --: po2 = (-1, 2)