平面上的点和线——Point类、Line类 (IV)

Description
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，两点确定一条线段。现在我们封装一个“Point类”和“Line类”来实现平面上的点的操作。
根据“append.cc”，完成Point类和Line类的构造方法和show()方法，输出各Line对象和Point对象的构造和析构次序。
接口描述：
Point::show()方法：按格式输出Point对象。
Line::show()方法：按格式输出Line对象。

Input

输入的第一行为N，表示后面有N行测试样例。

每行为两组坐标“x,y”，分别表示线段起点和终点的x坐标和y坐标，两组坐标间用一个空格分开，x和y的值都在double数据范围内。

Output
输出为多行，每行为一条线段，起点坐标在前终点坐标在后，每个点的X坐标在前，Y坐标在后，Y坐标前面多输出一个空格，用括号包裹起来。输出格式见sample。
C语言的输入输出被禁用。

Sample Input
4
0,0 1,1
1,1 2,3
2,3 4,5
0,1 1,0
Sample Output
Point : (1, -2) is created.
Point : (2, -1) is created.
Point : (0, 0) is created.
Point : (0, 0)
Point : (0, 0) is created.
Point : (0, 0) is created.
Line : (0, 0) to (0, 0) is created.
Point : (0, 0) is created.
Point : (0, 0) is created.
Line : (0, 0) to (0, 0) is created.
Point : (0, 0) is created.
Point : (0, 0) is created.
Line : (0, 0) to (0, 0) is created.
Point : (0, 0) is created.
Point : (0, 0) is created.
Line : (0, 0) to (0, 0) is created.\这里本来没有空格，但是为了格式的需要；

=========================
Line : (0, 0) to (1, 1)\这里本来没有空格，但是为了格式的需要；

=========================
Line : (1, 1) to (2, 3)\这里本来没有空格，但是为了格式的需要；

=========================
Line : (2, 3) to (4, 5)\这里本来没有空格，但是为了格式的需要；

=========================
Line : (0, 1) to (1, 0)\这里本来没有空格，但是为了格式的需要；

=========================
Point : (1, -2) is copied.
Point : (2, -1) is copied.
Line : (1, -2) to (2, -1) is created.
Point : (1, -2) is copied.
Point : (0, 0) is copied.
Line : (1, -2) to (0, 0) is created.
Point : (2, -1) is copied.
Point : (0, 0) is copied.
Line : (2, -1) to (0, 0) is created.
Point : (0, 0) is copied.
Point : (2, -1) is copied.
Line : (0, 0) to (2, -1) is created.
Line : (1, -2) to (2, -1)
Line : (1, -2) to (0, 0)
Line : (2, -1) to (0, 0)
Line : (0, 0) to (2, -1)
Line : (0, 0) to (2, -1) is erased.
Point : (2, -1) is erased.
Point : (0, 0) is erased.
Line : (2, -1) to (0, 0) is erased.
Point : (0, 0) is erased.
Point : (2, -1) is erased.
Line : (1, -2) to (0, 0) is erased.
Point : (0, 0) is erased.
Point : (1, -2) is erased.
Line : (1, -2) to (2, -1) is erased.
Point : (2, -1) is erased.
Point : (1, -2) is erased.
Line : (0, 1) to (1, 0) is erased.
Point : (1, 0) is erased.
Point : (0, 1) is erased.
Line : (2, 3) to (4, 5) is erased.
Point : (4, 5) is erased.
Point : (2, 3) is erased.
Line : (1, 1) to (2, 3) is erased.
Point : (2, 3) is erased.
Point : (1, 1) is erased.
Line : (0, 0) to (1, 1) is erased.
Point : (1, 1) is erased.
Point : (0, 0) is erased.
Point : (0, 0) is erased.
Point : (2, -1) is erased.
Point : (1, -2) is erased.
HINT

Append Code
append.cc,

int main()
{
    char c;
    int num, i;
    double x1, x2, y1, y2;
    Point p(1, -2), q(2, -1), t;
    t.show();
    std::cin>>num;
    Line line[num];
    for(i = 0; i < num; i++)
    {
        std::cout<<"=========================\n";
        std::cin>>x1>>c>>y1>>x2>>c>>y2;
        line[i].SetLine(x1, y1, x2, y2);
        line[i].show();
    }
    std::cout<<"=========================\n";
    Line l1(p, q), l2(p, t), l3(q, t), l4(t, q);
    l1.show();
    l2.show();
    l3.show();
    l4.show();
}

---

AC代码

#include <iostream>

using namespace std;
class Point
{
    friend class Line;
private:
    double _a,_b;
public:
    Point():_a(0),_b(0){cout<<"Point : ("<<_a<<", "<<_b<<") is created."<<endl;}
    Point(double a,double b):_a(a),_b(b){cout<<"Point : ("<<_a<<", "<<_b<<") is created."<<endl;}
    Point(const Point& p):_a(p._a),_b(p._b){cout<<"Point : ("<<_a<<", "<<_b<<") is copied."<<endl;}
    ~Point(){cout<<"Point : ("<<_a<<", "<<_b<<") is erased."<<endl;}
    void show(){cout<<"Point : ("<<_a<<", "<<_b<<")"<<endl;}
};
class Line
{
    friend class Point;
private:
    Point p1,p2;
public:
    Line():p1(0,0),p2(0,0){cout<<"Line : ("<<p1._a<<", "<<p1._b<<") to ("<<p2._a<<", "<<p2._b<<") is created."<<endl;}
    Line(double a,double b,double c,double d):p1(a,b),p2(c,d){cout<<"Line : ("<<p1._a<<", "<<p1._b<<") to ("<<p2._a<<", "<<p2._b<<") is created."<<endl;}
    void SetLine(double a,double b,double c,double d){p1._a=a,p1._b=b,p2._a=c,p2._b=d;}
    void show(){cout<<"Line : ("<<p1._a<<", "<<p1._b<<") to ("<<p2._a<<", "<<p2._b<<")"<<endl;}
    Line(Point& p,Point& q):p1(p),p2(q)//这里之所以Line(Point& p,Point& q)是因为不让其调用上面的拷贝构造函数，因为其后p1(p),p2(q)面已经调用了拷贝构造函数；
    {cout<<"Line : ("<<p1._a<<", "<<p1._b<<") to ("<<p2._a<<", "<<p2._b<<") is created."<<endl;}
    ~Line(){cout<<"Line : ("<<p1._a<<", "<<p1._b<<") to ("<<p2._a<<", "<<p2._b<<") is erased."<<endl;}
};
int main()
{
    char c;
    int num, i;
    double x1, x2, y1, y2;
    Point p(1, -2), q(2, -1), t;
    t.show();
    std::cin>>num;
    Line line[num];//定义同时就要初始化；
    for(i = 0; i < num; i++)
    {
        std::cout<<"=========================\n";
        std::cin>>x1>>c>>y1>>x2>>c>>y2;
        line[i].SetLine(x1, y1, x2, y2);
        line[i].show();
    }
    std::cout<<"=========================\n";
    Line l1(p, q), l2(p, t), l3(q, t), l4(t, q);
    l1.show();
    l2.show();
    l3.show();
    l4.show();
}