定义一个类，由point类派生出circle类（圆），由circle类派生出cylinder类（圆柱体）。将类的定义部分分别做3个头文件，对它们的成员函数的声明与实现分别作为3个源文件。对其成员函数的声音部分分别作为3个不同的源文件做成3个源文件。

好的，这是您要求的类的定义，分别存放在三个头文件中。

point.h：

#ifndef POINT_H
#define POINT_H

class Point {
public:
    Point(double x = 0, double y = 0);
    void setX(double x);
    double getX() const;
    void setY(double y);
    double getY() const;
private:
    double x, y;
};

#endif

circle.h：

#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;
private:
    double r;
};

#endif

cylinder.h：

#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 getVolume() const;
private:
    double h;
};

#endif

这是成员函数的声明，分别存放在三个源文件中。

point.cpp：

#include "point.h"

Point::Point(double x, double y) {
    setX(x);
    setY(y);
}

void Point::setX(double x) {
    this->x = x;
}

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

void Point::setY(double y) {
    this->y = y;
}

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

circle.cpp：

#include "circle.h"

#include <cmath>

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

void Circle::setR(double r) {
    this->r = r;
}

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

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

cylinder.cpp：

#include "cylinder.h"

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

void Cylinder::setH(double h) {
    this->h = h;
}

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

double Cylinder::getVolume() const {
    return getArea() * h;
}

最后，这是成员函数的实现，也分别存放在三个源文件中。

point_impl1.cpp：

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

using namespace std;

int main() {
    Point p(1, 2);
    cout << "x = " << p.getX() << ", y = " << p.getY() << endl;
    return 0;
}

circle_impl1.cpp：

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

using namespace std;

int main() {
    Circle c(1, 2, 3);
    cout << "x = " << c.getX() << ", y = " << c.getY() << ", r = " << c.getR() << endl;
    cout << "area = " << c.getArea() << endl;
    return 0;
}

cylinder_impl1.cpp：

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

using namespace std;

int main() {
    Cylinder c(1, 2, 3, 4);
    cout << "x = " << c.getX() << ", y = " << c.getY() << ", r = " << c.getR() << ", h = " << c.getH() << endl;
    cout << "volume = " << c.getVolume() << endl;
    return 0;
}

point_impl2.cpp：

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

using namespace std;

void printPoint(const Point& p) {
    cout << "x = " << p.getX() << ", y = " << p.getY() << endl;
}

int main() {
    Point p(1, 2);
    printPoint(p);
    return 0;
}

circle_impl2.cpp：

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

using namespace std;

void printCircle(const Circle& c) {
    cout << "x = " << c.getX() << ", y = " << c.getY() << ", r = " << c.getR() << endl;
    cout << "area = " << c.getArea() << endl;
}

int main() {
    Circle c(1, 2, 3);
    printCircle(c);
    return 0;
}

cylinder_impl2.cpp：

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

using namespace std;

void printCylinder(const Cylinder& c) {
    cout << "x = " << c.getX() << ", y = " << c.getY() << ", r = " << c.getR() << ", h = " << c.getH() << endl;
    cout << "volume = " << c.getVolume() << endl;
}

int main() {
    Cylinder c(1, 2, 3, 4);
    printCylinder(c);
    return 0;
}

point_impl3.cpp：

#include "point.h"

Point::Point(double x, double y) {
    setX(x);
    setY(y);
}

void Point::setX(double x) {
    this->x = x;
}

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

void Point::setY(double y) {
    this->y = y;
}

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

circle_impl3.cpp：

#include "circle.h"

#include <cmath>

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

void Circle::setR(double r) {
    this->r = r;
}

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

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

cylinder_impl3.cpp：

#include "cylinder.h"

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

void Cylinder::setH(double h) {
    this->h = h;
}

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

double Cylinder::getVolume() const {
    return getArea() * h;
}