C++第11周项目4 - 点类、圆类、圆柱类

课程首页地址：http://blog.csdn.net/sxhelijian/article/details/7910565，本周题目链接：http://blog.csdn.net/sxhelijian/article/details/8894095

【项目4】按以下的提示，由基类的设计和测试开始，逐渐地完成各个类的设计，并且完成要求的计算任务：

    （1）先建立一个Point(点)类，包含数据成员x,y(坐标点)；
    （2）以Point为基类，派生出一个Circle(圆)类，增加数据成员 (半径)；
    （3）再以Circle类为直接基类，派生出一个Cylinder(圆柱体)类，再增加数据成员h(高)。
     要求编写程序，设计出各类中基本的成员函数（包括构造函数、析构函数、修改数据成员和获取数据成员的公共接口、用于输出的重载运算符“<<”函数等），使之能用于处理以上类对象，最后求出圆格柱体的表面积、体积并输出。
   （提示：此任务可以分为三个子任务分成若干步骤进行。先声明基类，再声明派生类，逐级进行，分步调试。——这种方法适用于做任何的项目）

参考解答：
(1) 基类Point类及用于测试的main()函数

#include <iostream>using namespace std;class Point{public:    Point(double x=0,double y=0);  //构造函数    void setPoint(double,double);                  //设置坐标值    double getX( ) const    {        return x;    //读x坐标    }    double getY( ) const    {        return y;    //读y坐标    }    friend ostream & operator<<(ostream &,const Point &);//重载运算符“<<”protected:  //受保护成员    double x,y;};//Point的构造函数Point::Point(double a,double b){    x=a;    y=b;}//设置x和y的坐标值void Point::setPoint(double a,double b){    x=a;    y=b;}ostream & operator<<(ostream &output,const Point &p){    output<<"["<<p.x<<","<<p.y<<"]"<<endl;    return output;}int main( ){    Point p(3.5,6.4);    cout<<"x="<<p.getX( )<<",y="<<p.getY( )<<endl;    p.setPoint(8.5,6.8);    cout<<"p:"<<p<<endl;    return 0;}

(2) 声明派生类Circle及其测试函数

#include <iostream>using namespace std;class Point{public:    Point(double x=0,double y=0);  //构造函数    void setPoint(double,double);                  //设置坐标值    double getX( ) const    {        return x;    //读x坐标    }    double getY( ) const    {        return y;    //读y坐标    }    friend ostream & operator<<(ostream &,const Point &);//重载运算符“<<”protected:  //受保护成员    double x,y;};//Point的构造函数Point::Point(double a,double b){    x=a;    y=b;}//设置x和y的坐标值void Point::setPoint(double a,double b){    x=a;    y=b;}ostream & operator<<(ostream &output,const Point &p){    output<<"["<<p.x<<","<<p.y<<"]"<<endl;    return output;}class Circle:public Point   //circle是Point类的公用派生类{public:    Circle(double x=0,double y=0,double r=0);  //构造函数    void setRadius(double);                  //设置半径值    double getRadius( ) const;               //读取半径值    double area ( ) const;                   //计算圆面积    friend ostream &operator<<(ostream &,const Circle &);//重载运算符“<<”protected:    double radius;};//定义构造函数，对圆心坐标和半径初始化Circle::Circle(double a,double b,double r):Point(a,b),radius(r) { }//设置半径值void Circle::setRadius(double r){    radius=r;}//读取半径值double Circle::getRadius( ) const{    return radius;}//计算圆面积double Circle::area( ) const{    return 3.14159*radius*radius;}//重载运算符“<<”，使之按规定的形式输出圆的信息ostream &operator<<(ostream &output,const Circle &c){    output<<"Center=["<<c.x<<", "<<c.y<<"], r="<<c.radius<<", area="<<c.area( )<<endl;    return output;}int main( ){    Circle c(3.5,6.4,5.2);    cout<<"original circle:\nx="<<c.getX()<<", y="<<c.getY()<<", r="<<c.getRadius( ) <<", area="<<c.area( )<<endl;    c.setPoint(5,5);    cout<<"new circle:\n"<<c;    return 0;}

(3) 声明Circle的派生类Cylinder及测试函数

#include <iostream>using namespace std;class Point{public:    Point(double x=0,double y=0);  //构造函数    void setPoint(double,double);                  //设置坐标值    double getX( ) const    {        return x;    //读x坐标    }    double getY( ) const    {        return y;    //读y坐标    }    friend ostream & operator<<(ostream &,const Point &);//重载运算符“<<”protected:  //受保护成员    double x,y;};//Point的构造函数Point::Point(double a,double b){    x=a;    y=b;}//设置x和y的坐标值void Point::setPoint(double a,double b){    x=a;    y=b;}ostream & operator<<(ostream &output,const Point &p){    output<<"["<<p.x<<","<<p.y<<"]"<<endl;    return output;}class Circle:public Point   //circle是Point类的公用派生类{public:    Circle(double x=0,double y=0,double r=0);  //构造函数    void setRadius(double);                  //设置半径值    double getRadius( ) const;               //读取半径值    double area ( ) const;                   //计算圆面积    friend ostream &operator<<(ostream &,const Circle &);//重载运算符“<<”protected:    double radius;};//定义构造函数，对圆心坐标和半径初始化Circle::Circle(double a,double b,double r):Point(a,b),radius(r) { }//设置半径值void Circle::setRadius(double r){    radius=r;}//读取半径值double Circle::getRadius( ) const{    return radius;}//计算圆面积double Circle::area( ) const{    return 3.14159*radius*radius;}//重载运算符“<<”，使之按规定的形式输出圆的信息ostream &operator<<(ostream &output,const Circle &c){    output<<"Center=["<<c.x<<", "<<c.y<<"], r="<<c.radius<<", area="<<c.area( )<<endl;    return output;}class Cylinder:public Circle{public:    Cylinder (double x=0,double y=0,double r=0,double h=0);//构造函数    void setHeight(double);                      //设置圆柱高    double getHeight( ) const;                    //读取圆柱高    double area( ) const;                         //计算圆表面积    double volume( ) const;                       //计算圆柱体积    friend ostream& operator<<(ostream&,const Cylinder&);//重载运算符“<<”protected:    double height;                               //圆柱高};//定义构造函数Cylinder::Cylinder(double a,double b,double r,double h) :Circle(a,b,r),height(h) {}//设置圆柱高void Cylinder::setHeight(double h){    height=h;}//读取圆柱高double Cylinder::getHeight( ) const{    return height;}//计算圆柱表面积double Cylinder::area( ) const{    return 2*Circle::area( )+2*3.14159*radius*height;}//计算圆柱体积double Cylinder::volume() const{    return Circle::area()*height;}//重载运算符“<<”ostream &operator<<(ostream &output,const Cylinder& cy){    output<<"Center=["<<cy.x<<","<<cy.y<<"], r="<<cy.radius<<", h="<<cy.height    <<"\narea="<<cy.area( )<<", volume="<<cy.volume( )<<endl;    return output;}int main( ){    Cylinder cy1(3.5,6.4,5.2,10);    cout<<"\noriginal cylinder:\nx="<<cy1.getX( )<<", y="<<cy1.getY( )<<", r="        <<cy1.getRadius( )<<", h="<<cy1.getHeight( )<<"\narea="<<cy1.area()        <<",volume="<<cy1.volume()<<endl;    cy1.setHeight(15);    cy1.setRadius(7.5);    cy1.setPoint(5,5);    cout<<"\nnew cylinder:\n"<<cy1;    return 0;}