在数学上，平面直角坐标系上的点用X轴和Y轴上的两个坐标值唯一确定。现在我们封装一个“Point类”来实现平面上的点的操作。

根据“append.cc”，完成Point类的构造方法和show()方法，输出各Point对象的构造和析构次序。实现showPoint()函数。

接口描述：
showPoint()函数按输出格式输出Point对象，调用Point::show()方法实现。
Point::show()方法：按输出格式输出Point对象。

输入多行，每行为一组坐标“x,y”，表示点的x坐标和y坐标，x和y的值都在double数据范围内。

1,2
3,3
2,1

Point : (0, 0) is created.
Point : (1, 2) is created.
Point : (1, 2) is copied.
Point : (1, 2)
Point : (1, 2) is erased.
Point : (1, 2) is erased.
Point : (3, 3) is created.
Point : (3, 3) is copied.
Point : (3, 3)
Point : (3, 3) is erased.
Point : (3, 3) is erased.
Point : (2, 1) is created.
Point : (2, 1) is copied.
Point : (2, 1)
Point : (2, 1) is erased.
Point : (2, 1) is erased.
Point : (0, 0) is copied.
Point : (1, 1) is created.
Point : (0, 0) is copied.
Point : (1, 1) is copied.
Point : (0, 0) is copied.
Point : (0, 0)
Point : (1, 1)
Point : (0, 0)
Point : (0, 0) is erased.
Point : (1, 1) is erased.
Point : (0, 0) is erased.
Point : (1, 1) is erased.
Point : (0, 0) is erased.
Point : (0, 0) is erased.

思考构造函数、拷贝构造函数、析构函数的调用时机。

append.cc,

 

int main()
{
    char c;
    double a, b;
    Point q;
    while(std::cin>>a>>c>>b)
    {
        Point p(a, b);
        showPoint(p);
    }
    Point q1(q), q2(1);
    showPoint(q1, q2, q);
}

 

代码

#include <iostream>
#include <iomanip>

using namespace std;

class Point
{
private:
    double x,y;
public:
    Point():x(0),y(0)
    {
        cout<<setprecision(16)<< "Point : (" << x << ", " << y << ") is created."<<endl;
    }
    Point(double a,double b):x(a),y(b)
    {
        cout<<setprecision(16)<< "Point : (" << x << ", " << y << ") is created."<<endl;
    }
    Point(double a):x(a),y(1)
    {
        cout<<setprecision(16)<< "Point : (" << x << ", " << y << ") is created."<<endl;
    }
    ~Point()
    {
         cout<<setprecision(16)<< "Point : (" << x << ", " << y << ") is erased."<<endl;
    }
    Point(const Point &p)
    {
        x=p.x;
        y=p.y;
        cout <<setprecision(16)<<"Point : ("<<p.x<<", "<<p.y<<")"<<" is copied."<<endl;
    }
    void show()
    {
        cout <<setprecision(16)<<"Point : ("<<x<<", "<<y<<")"<<endl;
    }

};
    void showPoint(Point a)
    {
        a.show();
    }
    void showPoint(Point a,Point b,Point c)
    {
        a.show();
        b.show();
        c.show();
    }
int main()
{
    char c;
    double a, b;
    Point q;
    while(std::cin>>a>>c>>b)
    {
        Point p(a, b);
        showPoint(p);
    }
    Point q1(q), q2(1);
    showPoint(q1, q2, q);
}