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。
Line::SetLine(double, double, double, double)方法：设置Line对象起点的x,y坐标（第一个和第二参数）和终点的x,y坐标（第三个和第四个坐标），并返回本对象
Line::SetLine(const Point &, const Point &)方法：设置Line对象的起点（第一个参数）和终点（第二个坐标），并返回本对象
Line::SetLine(const Line&)方法：设置Line对象，复制参数的坐标，并返回本对象
Line::readLine()方法：从标准输入上读入坐标，格式见Sample
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.
Line : (0, 0) to (1, 1)
Line : (1, 1) to (2, 3)
Line : (2, 3) to (4, 5)
Line : (0, 1) to (1, 0)
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 : (1, -2) is copied.
Point : (2, -1) is copied.
Line : (1, -2) to (2, -1) is copied.
Line : (1, -2) to (2, -1)
Line : (1, -2) to (2, -1)
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 (2, -1) is erased.
Point : (2, -1) 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
#include <iostream>
using namespace std; class Point{ friend class Line; private: double x, y; public: Point(double a=0,double b=0):x(a),y(b){cout<<"Point : ("<<x<<", "<<y<<") is created."<<endl;} Point(const Point&p):x(p.x),y(p.y){cout<<"Point : ("<<x<<", "<<y<<") is copied."<<endl;} ~Point(){cout<<"Point : ("<<x<<", "<<y<<") is erased."<<endl;} void show(){cout<<"Point : ("<<x<<", "<<y<<")"<<endl;} }; class Line{ friend class Point; private: Point p1,p2; public: Line(const Line &t):p1(t.p1),p2(t.p2){ cout << "Line : (" << p1.x << ", " << p1.y << ") to (" << p2.x <<", " << p2.y << ") is copied." << endl; } Line(Point &p,Point &q):p1(p),p2(q){cout<<"Line : ("<<p1.x<<", "<<p1.y<<") to ("<<p2.x<<", "<<p2.y<<") is created."<<endl;} Line(double x1=0,double y1=0,double x2=0,double y2=0):p1(x1,y1),p2(x2,y2){cout<<"Line : ("<<p1.x<<", "<<p1.y<<") to ("<<p2.x<<", "<<p2.y<<") is created."<<endl;} ~Line(){cout<<"Line : ("<<p1.x<<", "<<p1.y<<") to ("<<p2.x<<", "<<p2.y<<") is erased."<<endl;} void SetLine(double a,double b,double c,double d){p1.x=a;p1.y=b;p2.x=c;p2.y=d;} void readLine() { double x1, y1, x2, y2; char c; cin >> x1 >> c >> y1 >> x2 >> c >> y2; SetLine(x1, y1, x2, y2); } Line &setLine(const Point& t1, const Point& t2){ p1=t1; p2=t2; return *this; } Line &setLine(const Line& t) { p1= t.p1; p2 = t.p2; return *this; } void show(){cout<<"Line : ("<<p1.x<<", "<<p1.y<<") to ("<<p2.x<<", "<<p2.y<<")"<<endl;} };int main(){ int num, i; Point p(1, -2), q(2, -1), t; t.show(); std::cin>>num; Line line[num]; for(i = 0; i < num; i++) { line[i].readLine(); line[i].show(); } Line l1(p, q), l2(p,t), l3(q,t), l4(l1); l1.show(); l2.setLine(l1).show(); l3.show(); l4.setLine(t,q).show();}