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 : (1, 1) is created.
Line : (0, 0) to (1, 1) is created.
Line : (0, 0) to (1, 1)
Line : (0, 0) to (1, 1) is erased.
Point : (1, 1) is erased.
Point : (0, 0) is erased.
=========================
Point : (1, 1) is created.
Point : (2, 3) is created.
Line : (1, 1) to (2, 3) is created.
Line : (1, 1) to (2, 3)
Line : (1, 1) to (2, 3) is erased.
Point : (2, 3) is erased.
Point : (1, 1) is erased.
=========================
Point : (2, 3) is created.
Point : (4, 5) is created.
Line : (2, 3) to (4, 5) is created.
Line : (2, 3) to (4, 5)
Line : (2, 3) to (4, 5) is erased.
Point : (4, 5) is erased.
Point : (2, 3) is erased.
=========================
Point : (0, 1) is created.
Point : (1, 0) is created.
Line : (0, 1) to (1, 0) is created.
Line : (0, 1) to (1, 0)
Line : (0, 1) to (1, 0) is erased.
Point : (1, 0) is erased.
Point : (0, 1) is erased.
=========================
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.
Point : (0, 0) is erased.
Point : (2, -1) is erased.
Point : (1, -2) is erased.
##代码如下：
#include
using namespace std;
class Point
{
friend class Line;
double x,y;
public:
Point(){x=0;y=0;cout<<"Point : ("<<x<<", "<<y<<") is created."<<endl;}
Point(double a,double b)
{
x=a;y=b;
cout<<"Point : ("<<x<<", "<<y<<") is created."<<endl;
}
void show ()
{
cout<<"Point : ("<<x<<", "<<y<<")"<<endl;
}
double w()
{
return x;
}
double z()
{
return y;
}
~Point()
{
cout<<"Point : ("<<x<<", "<<y<<") is erased."<<endl;
}
Point(const Point &p)
{
x=p.x;
y=p.y;
cout<<"Point : ("<<x<<", "<<y<<") is copied."<<endl;
}
};
class Line
{
friend class Point;
Point q,w;
public:
Line(double x1,double y1,double x2,double y2):q(x1,y1),w(x2,y2)
{
cout<<"Line : ("<<q.x<<", "<<q.y<<") to ("<<w.x<<", "<<w.y<<") is created."<<endl;
}
Line(Point &r,Point &t):q(r),w(t)
{
cout<<"Line : ("<<q.x<<", "<<q.y<<") to ("<<w.x<<", "<<w.y<<") is created."<<endl;
}
void show ()
{
cout<<"Line : ("<<q.x<<", "<<q.y<<") to ("<<w.x<<", "<<w.y<<")"<<endl;
}
~Line()
{
cout<<"Line : ("<<q.x<<", "<<q.y<<") to ("<<w.x<<", "<<w.y<<") 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;
for(i = 1; i <= num; i++)
{
std::cout<<"=========================\n";
std::cin>>x1>>c>>y1>>x2>>c>>y2;
Line line(x1, y1, x2, y2);
line.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();
}
