设有一个点类Point的定义如下： Point { public: Point() {x = 0; y = 0; } Point(double xv,double yv) {x = xv;y = yv;} Point(Point& pt) { x = pt.x; y = pt.y; } double getx() { return x; } double gety() { return y; } double Area() { return 0; } void Show() { cout<<"x="<<x<<' '<<"y="<<y<<endl; } private: double x,y; }; 编写程序，以点point类为基类，派生出矩形类Rectangle和圆类Circle。矩形由左上角的顶点和长、宽定义。圆由圆心和半径定义。派生类Circle中新增的成员函数position(Point &pt)用于判断任一坐标点是在圆内、还是在圆的边缘上，还是在圆外。

以下是基于点类Point的派生类Rectangle和Circle的定义：

class Rectangle : public Point {
public:
    Rectangle(): Point(), length(0), width(0) {}
    Rectangle(double xv, double yv, double l, double w): Point(xv, yv), length(l), width(w) {}
    Rectangle(Point& pt, double l, double w): Point(pt), length(l), width(w) {}
    double getLength() { return length; }
    double getWidth() { return width; }
    double Area() { return length * width; }
    void Show() { 
        cout << "Left top corner: ";
        Point::Show();
        cout << "Length: " << length << " Width: " << width << endl; 
    }
private:
    double length, width;
};

class Circle : public Point {
public:
    Circle(): Point(), radius(0) {}
    Circle(double xv, double yv, double r): Point(xv, yv), radius(r) {}
    Circle(Point& pt, double r): Point(pt), radius(r) {}
    double getRadius() { return radius; }
    double Area() { return PI * radius * radius; }
    void Show() { 
        cout << "Center: ";
        Point::Show();
        cout << "Radius: " << radius << endl; 
    }
    int position(Point& pt) {
        double distance = sqrt(pow(pt.getx()-getx(), 2) + pow(pt.gety()-gety(), 2));
        if (distance < radius) return 1;
        else if (distance == radius) return 0;
        else return -1;
    }
private:
    double radius;
    const double PI = 3.14159265358979323846264338327;
};

其中，Rectangle类表示矩形，包含左上角的顶点和长宽，其派生自Point类；Circle类表示圆，包含圆心和半径，其也派生自Point类，新增了成员函数position，用于判断任一坐标点在圆内、圆的边缘上或圆外。