习题 12.1 在例12.1程序基础上作一些修改。定义Point类，由Point类派生出Circle类，再由Circle类派生出Cylinder类。将类的定义部分分别作为3个头文件，对它们的成员。。。

落日映苍穹つ 2022-05-10 01:48 156阅读 0赞

### C++程序设计（第三版） 谭浩强 习题12.1 个人设计 ###

#### 习题 12.1 在例12.1程序基础上作一些修改。定义Point类，由Point类派生出Circle类，再由Circle类派生出Cylinder类。将类的定义部分分别作为3个头文件，对它们的成员函数的声明部分分别作为3个源文件，在主函数中用\#include命令把它们包含进来，形成一个完整的程序，并上机运行。 ####

代码块：

Point.h头文件

#include <iostream>
    using namespace std;
    class Point
    {
    public:
    	Point(double x=0, double y=0);
    	void setPoint(double, double);
    	double getX() const{return x;}
    	double getY() const{return y;}
    	friend ostream & operator<<(ostream &, const Point &);
    protected:
    	double x, y;
    };

Circle.h头文件

class Circle: public Point
    {
    public:
    	Circle (double x=0, double y=0, double r=0);
    	void setRadius(double);
    	double getRadius() const;
    	double area() const;
    	friend ostream& operator<<(ostream &, const Circle &);
    protected:
    	double radius;
    };

Cylinder.h头文件

class Cylinder: public Circle
    {
    public:
    	Cylinder(double x=0, double y=0, double r=0, double h=0);
    	void setHeight(double);
    	double getHeight() const;
    	double area() const;
    	double volume() const;
    	friend ostream& operator<<(ostream &, const Cylinder &);
    protected:
    	double height;
    };

PointFun函数

#include <iostream>
    #include "Point.h"
    using namespace std;
    Point::Point(double a, double b)
    {
    	x=a; y=b;
    }
    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;
    }

CircleFun函数

#include <iostream>
    #include "Point.h"
    #include "Circle.h"
    using namespace std;
    Circle::Circle(double a, double b, double r): Point(a, b), radius(r){}
    void Circle::setRadius(double r){radius=r;}
    double Circle::getRadius() const { return radius;}
    double Circle::area() const {return 3.14159*radius*radius;}
    ostream& operator<<(ostream &output, const Circle &c)
    {
    	output<<"Center=["<<c.x<<", "<<c.y<<"], r="<<c.radius<<", area="<<c.area()<<endl;
    	return output;
    }

CylinderFun函数

#include <iostream>
    #include "Point.h"
    #include "Circle.h"
    #include "Cylinder.h"
    using namespace std;
    Cylinder::Cylinder(double a, double b, double r, double h)
    	:Circle(a, b, r), height(h){}
    void Cylinder::setHeight(double h) {height=h;}
    double Cylinder::getHeight() const {return height;}
    double Cylinder::area() const {return 2*Circle::area()+2*3.14159*radius*height;}
    double Cylinder::volume() const {return Circle::area()*height;}
    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;
    }

main函数

#include <iostream>
    #include "Point.h"
    #include "Circle.h"
    #include "Cylinder.h"
    using namespace std;
    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;
    	Point &pRef=cy1;
    	cout<<"\npRef as a Point:"<<pRef;
    	Circle &cRef=cy1;
    	cout<<"\ncRef as a Circle:"<<cRef;
    	system("pause");
    	return 0;
    }