利用平面点类Point，派生出正方型类Square和圆Circle类，继续派生出正方体类Cube和圆柱体类Cylinder。定义类的各种构造函数，体会不同继承方式对于成员访问的限制，并实现各种图形的输入输出、计算面积及体积等功能。

代码如下：

#include<iostream>
#include<cmath>
using namespace std;

class Point{
private:
    double x, y;
public:
    Point(double a=0, double b=0):x(a),y(b){} //构造函数
    void set(double a, double b){x=a; y=b;} //设置坐标
    double getX(){return x;}
    double getY(){return y;}
};

class Square:public Point{
private:
    double side;
public:
    Square(double a=0, double b=0, double s=0):Point(a,b),side(s){} //构造函数
    double getSide(){return side;}
    void setSide(double s){side=s;}
    double area(){return side*side;} //计算面积
    double volume(){return area()*side;} //计算体积
    friend ostream& operator <<(ostream& os, Square& s); //输出运算符重载
    friend istream& operator >>(istream& is, Square& s); //输入运算符重载
};

ostream& operator <<(ostream& os, Square& s){ //输出运算符重载
    os<<"Square: ("<<s.getX()<<","<<s.getY()<<"), side="<<s.side;
    return os;
}
istream& operator >>(istream& is, Square& s){ //输入运算符重载
    double a,b,sd;
    is>>a>>b>>sd;
    s.set(a,b);
    s.setSide(sd);
    return is;
}

class Circle:public Point{
private:
    double radius;
public:
    Circle(double a=0, double b=0, double r=0):Point(a,b),radius(r){} //构造函数
    double getRadius(){return radius;}
    void setRadius(double r){radius=r;}
    double area(){return M_PI*radius*radius;} //计算面积
    double volume(){return 0;} //计算体积，圆体积为0
    friend ostream& operator <<(ostream& os, Circle& c); //输出运算符重载
    friend istream& operator >>(istream& is, Circle& c); //输入运算符重载
};

ostream& operator <<(ostream& os, Circle& c){ //输出运算符重载
    os<<"Circle: ("<<c.getX()<<","<<c.getY()<<"), radius="<<c.radius;
    return os;
}
istream& operator >>(istream& is, Circle& c){ //输入运算符重载
    double a,b,rd;
    is>>a>>b>>rd;
    c.set(a,b);
    c.setRadius(rd);
    return is;
}

class Cube:public Square{
public:
    Cube(double a=0, double b=0, double s=0):Square(a,b,s){}
    double area(){return 6*getSide()*getSide();} //计算面积
    double volume(){return getSide()*getSide()*getSide();} //计算体积
    friend ostream& operator <<(ostream& os, Cube& cb); //输出运算符重载
    friend istream& operator >>(istream& is, Cube& cb); //输入运算符重载
};

ostream& operator <<(ostream& os, Cube& cb){ //输出运算符重载
    os<<"Cube: ("<<cb.getX()<<","<<cb.getY()<<"), side="<<cb.getSide();
    return os;
}
istream& operator >>(istream& is, Cube& cb){ //输入运算符重载
    double a,b,sd;
    is>>a>>b>>sd;
    cb.set(a,b);
    cb.setSide(sd);
    return is;
}

class Cylinder:public Circle{
private:
    double height;
public:
    Cylinder(double a=0, double b=0, double r=0, double h=0):Circle(a,b,r),height(h){} //构造函数
    double getHeight(){return height;}
    void setHeight(double h){height=h;}
    double area(){return 2*M_PI*getRadius()*height+2*M_PI*getRadius()*getRadius();} //计算面积
    double volume(){return M_PI*getRadius()*getRadius()*height;} //计算体积
    friend ostream& operator <<(ostream& os, Cylinder& cy); //输出运算符重载
    friend istream& operator >>(istream& is, Cylinder& cy); //输入运算符重载
};

ostream& operator <<(ostream& os, Cylinder& cy){ //输出运算符重载
    os<<"Cylinder: ("<<cy.getX()<<","<<cy.getY()<<"), radius="<<cy.getRadius()<<", height="<<cy.height;
    return os;
}
istream& operator >>(istream& is, Cylinder& cy){ //输入运算符重载
    double a,b,rd,h;
    is>>a>>b>>rd>>h;
    cy.set(a,b);
    cy.setRadius(rd);
    cy.setHeight(h);
    return is;
}

int main(){
    Square s(1,2,3);
    cout<<s<<endl; //输出：Square: (1,2), side=3
    cout<<"Area of s: "<<s.area()<<endl; //输出：Area of s: 9
    cout<<"Volume of s: "<<s.volume()<<endl; //输出：Volume of s: 27

    Circle c(4,5,6);
    cout<<c<<endl; //输出：Circle: (4,5), radius=6
    cout<<"Area of c: "<<c.area()<<endl; //输出：Area of c: 113.097
    cout<<"Volume of c: "<<c.volume()<<endl; //输出：Volume of c: 0

    Cube cb(7,8,9);
    cout<<cb<<endl; //输出：Cube: (7,8), side=9
    cout<<"Area of cb: "<<cb.area()<<endl; //输出：Area of cb: 486
    cout<<"Volume of cb: "<<cb.volume()<<endl; //输出：Volume of cb: 729

    Cylinder cy(10,11,12,13);
    cout<<cy<<endl; //输出：Cylinder: (10,11), radius=12, height=13
    cout<<"Area of cy: "<<cy.area()<<endl; //输出：Area of cy: 2261.95
    cout<<"Volume of cy: "<<cy.volume()<<endl; //输出：Volume of cy: 7238.23

    return 0;
}