#include <iostream>

using std::cout;
using std::endl;


class Line
{
public:
 Line(int x1, int y1, int x2, int y2)
 : _pt1(x1, y1)
 , _pt2(x2, y2)
 {
 cout << "Line(int, int, int, int)" << endl;
 }

 void printLine() const
 {
 _pt1.print();
 cout << "----->";
 _pt2.print();
 cout << endl;
 }

 ~Line()
 {
 cout << "~Line()" << endl;
 }

private:
 //内部类
 //一个类A的产生是为另外一个类B服务的,将A作为B的内部类
 class Point
 {
 public:
 Point(int ix = 0, int iy = 0)
 : _ix(ix)
 , _iy(iy)
 {
 cout << "Point(int = 0, int = 0)" << endl;
 }
 
 void print() const
 {
 cout << "(" << _ix 
 << ", " << _iy
 << ")";
 }
 
 
 ~Point()
 {
 cout << "~Point()" << endl;
 }
 
 private:
 int _ix;
 int _iy;
 };

private:
 Point _pt1;
 Point _pt2;
};

int main(int argc, char **argv)
{
 /* Line::Point pt(1, 2);//error */
 Line line(1, 2, 3, 4);
 cout << "line = ";
 line.printLine();
 return 0;
}