C++
1.点-圆-圆柱
2.覆盖面向对象程序设计中的封装、继承和多态三大基本特征。
3.基类和派生类分别拥有不少于6个成员函数(函数功能可自行确定)，至少包括构造函数、拷贝构造函数和析构函数。
4.在基类或派生类中进行运算符重载的操作，所重载的运算符不限，但个数至少为2个，一个重载为成员函数，一个重载为友元函数。

#include <stdlib.h>
#include <iostream>
using namespace std;
class Point  //点类
{
private:
    int px,py; //x和y坐标值
public:
    Point() {}//默认无参构造函数
    ~Point() {}//析构函数
    Point(int x,int y) {px = x;py = y;} //带参构造函数
    Point(Point &p) {px = p.getX();py = p.getY();} //拷贝构造函数
    int getX() {return px;}
    int getY() {return py;}
    void setX(int x) {px = x;}
    void setY(int y) {py = y;}
};

class Circle : public Point
{
private:
    int radius;
public:
    Circle() {}
    ~Circle() {}
    Circle(int x,int y,int r) : Point(x,y){radius = r;}
    Circle(Circle &c) {radius = c.getR();setX(c.getX());setY(c.getY());}
    int getR() {return radius;}
    void setR(int r) {radius = r;}
    virtual float getArea() {return 3.14159*radius*radius;}  //虚函数，计算面积
};

class Cylinder : public Circle
{
private:
    int high;
public:
    Cylinder() {}
    ~Cylinder() {}
    Cylinder(int x,int y,int r,int h) : Circle(x,y,r){high = h;}
    Cylinder(Cylinder &c) {high = c.getH();setR(c.getR());setX(c.getX());setY(c.getY());}
    int getH() {return high;}
    void setH(int h) {high = h;}
    float getVolume() {return Circle::getArea()*high;}  //计算体积
    float getArea() {return 2*3.14159*getR()*high;} //计算面积
    void operator = (Cylinder &c) {high = c.getH();setR(c.getR());setX(c.getX());setY(c.getY());}  //赋值操作符重载
    friend bool operator == (Cylinder &c1,Cylinder &c2);//等于操作符重载
};
bool operator == (Cylinder &c1,Cylinder &c2)
{
    if(c1.getX() == c2.getX() && c1.getY() == c2.getY() && c1.getR() == c2.getR() && c1.getH() == c2.getH())
        return true;
    return false;
}

int main()
{
    Cylinder c1(10,20,5,20);
    Cylinder c2(c1);            //拷贝构造函数测试
    Cylinder c3 = c1;    //赋值操作符测试
    if(c3 == c2)    //等于操作符测试
        cout<<"c3与c2相等"<<endl;
    cout<<"圆柱体积为"<<c3.getVolume()<<endl;    //强制调用基类虚函数测试
    Circle *p = &c1;
    cout<<"圆柱面积为"<<p->getArea()<<endl;  //虚函数测试
    return 0;
}