C++ 走向远洋——44（项目一、点—圆—圆柱类族的设计、派生类）

*/
 * Copyright (c) 2016，烟台大学计算机与控制工程学院
 * All rights reserved.
 * 文件名：text.cpp
 * 作者：常轩
 * 微信公众号：Worldhello
 * 完成日期：2016年5月8日
 * 版本号：V1.0
 * 问题描述：类的派生
 * 程序输入：无
 * 程序输出：见运行结果
 */
#include <iostream>      //           点类的实现
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
    void show();
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;
}

void Point::show()
{
    cout<<"（"<<x<<","<<y<<"）"<<endl;
}

int main( )
{
    Point p(2.4,5.1);
    p.show();
    p.setPoint(1.8,3.2);
    p.show();
    return 0;
}

运行结果：

#include <iostream>                     //圆类的实现 
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
    }
    void show();
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;
}

void Point::show()
{
    cout<<"["<<x<<","<<y<<"]"<<endl;
}

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
    void show();
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;
}

//输出圆的信息
void Circle::show()
{
    cout<<"Center=（"<<x<<", "<<y<<"）, r="<<radius<<", area="<<area( )<<endl;
}

int main( )
{
    Circle c(3.1,5,6.7);
    cout<<"original circle:
";
    c.show();
    c.setPoint(3,3);
    cout<<"new circle:
";
    c.show();
    return 0;
}

运行结果：

#include <iostream>                  //圆柱类的实现
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
    }
    void show();
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;
}

void Point::show()
{
    cout<<"["<<x<<","<<y<<"]"<<endl;
}

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
    void show();
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;
}

//输出圆的信息
void Circle::show()
{
    cout<<"Center=["<<x<<", "<<y<<"], r="<<radius<<", area="<<area( )<<endl;
}


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;                         //计算圆柱表面积
    double volume( ) const;                       //计算圆柱体积
    void show();
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;
}

void Cylinder::show()
{
    cout<<"Center=["<<x<<","<<y<<"], r="<<radius<<", h="<<height
        <<"
area="<<area( )<<", volume="<<volume( )<<endl;
}

int main( )
{
    Cylinder cy1(3.5,6.4,5.2,10);
    cout<<"
original cylinder:
x=";
    cy1.show();
    cy1.setHeight(15);
    cy1.setRadius(7.5);
    cy1.setPoint(5,5);
    cout<<"
new cylinder:
";
    cy1.show();
    return 0;
}

运行结果：