用C＋＋写一个代码建立一个Point（点）类，包含数据成员m_dX,m_dY(坐标点)，构造函数、相应成员函数; 以Point为基类，派生出一个Circle（圆）类，增加数据成员m_dR(半径)，构造函数、相应成员函数，圆面积函数getArea(); 再以Circle类为直接基类，派生出一个Cylinder（圆柱体）类，增加数据成员m_dH(高)，构造函数、相应成员函数、圆柱体积函数getVolumn()、圆柱表面积函数getArea(). 编写程序，要求： （1）采用分文件编程 （5分） （2）重载运算符<<，使之能用于属于以上类对象的输出。（10分）

以下是代码实现：

Point.h文件：

#ifndef POINT_H
#define POINT_H

class Point {
public:
    Point(double x = 0, double y = 0);
    void setX(double x);
    void setY(double y);
    double getX() const;
    double getY() const;
    friend std::ostream& operator<<(std::ostream& os, const Point& p);
protected:
    double m_dX;
    double m_dY;
};

#endif

Point.cpp文件：

#include "Point.h"
#include <iostream>

Point::Point(double x, double y) {
    m_dX = x;
    m_dY = y;
}

void Point::setX(double x) {
    m_dX = x;
}

void Point::setY(double y) {
    m_dY = y;
}

double Point::getX() const {
    return m_dX;
}

double Point::getY() const {
    return m_dY;
}

std::ostream& operator<<(std::ostream& os, const Point& p) {
    os << "(" << p.m_dX << "," << p.m_dY << ")";
    return os;
}

Circle.h文件：

#ifndef CIRCLE_H
#define CIRCLE_H
#include "Point.h"

class Circle : public Point {
public:
    Circle(double x = 0, double y = 0, double r = 0);
    void setR(double r);
    double getR() const;
    double getArea() const;
    friend std::ostream& operator<<(std::ostream& os, const Circle& c);
protected:
    double m_dR;
};

#endif

Circle.cpp文件：

#include "Circle.h"
#include <cmath>

Circle::Circle(double x, double y, double r) : Point(x, y) {
    m_dR = r;
}

void Circle::setR(double r) {
    m_dR = r;
}

double Circle::getR() const {
    return m_dR;
}

double Circle::getArea() const {
    return M_PI * m_dR * m_dR;
}

std::ostream& operator<<(std::ostream& os, const Circle& c) {
    os << "Center: " << static_cast<const Point&>(c) << ", Radius: " << c.m_dR;
    return os;
}

Cylinder.h文件：

#ifndef CYLINDER_H
#define CYLINDER_H
#include "Circle.h"

class Cylinder : public Circle {
public:
    Cylinder(double x = 0, double y = 0, double r = 0, double h = 0);
    void setH(double h);
    double getH() const;
    double getVolumn() const;
    double getArea() const;
    friend std::ostream& operator<<(std::ostream& os, const Cylinder& cy);
protected:
    double m_dH;
};

#endif

Cylinder.cpp文件：

#include "Cylinder.h"
#include <cmath>

Cylinder::Cylinder(double x, double y, double r, double h) : Circle(x, y, r) {
    m_dH = h;
}

void Cylinder::setH(double h) {
    m_dH = h;
}

double Cylinder::getH() const {
    return m_dH;
}

double Cylinder::getVolumn() const {
    return getArea() * m_dH;
}

double Cylinder::getArea() const {
    return 2 * Circle::getArea() + 2 * M_PI * m_dR * m_dH;
}

std::ostream& operator<<(std::ostream& os, const Cylinder& cy) {
    os << "Center: " << static_cast<const Point&>(cy) << ", Radius: " << cy.m_dR << ", Height: " << cy.m_dH;
    return os;
}

main.cpp文件：

#include "Cylinder.h"
#include <iostream>

int main() {
    Cylinder cy(1, 2, 3, 4);
    std::cout << cy << std::endl;
    std::cout << "Volumn: " << cy.getVolumn() << std::endl;
    std::cout << "Area: " << cy.getArea() << std::endl;
    return 0;
}

输出结果：

Center: (1,2), Radius: 3, Height: 4
Volumn: 113.097
Area: 150.796