Shape类派生了Circle类和Rectangle类，请阅读主函数代码，完成Shape类、Circle类、Rectangle类的定义 【样例输入】 无 【样例输出】 Rectangle: Width=3.5,Height=7.2 Area=25.2 Perimeter=21.4 Circle: R=2.3 Area=16.619 Perimeter=14.4513 Shape Area=0 Perimeter=0 #include <iostream> #define PI 3.14159 using namespace std; class Shape { }; class Circle:public Shape { }; class Rectangle:public Shape { }; int main() { Rectangle recObj(7.2,3.5); recObj.print(); cout<<"Area="<<recObj.getArea()<<" Perimeter="<<recObj.getPerimeter()<<endl; Circle circleObj(2.3); circleObj.print(); cout<<"Area="<<circleObj.getArea()<<" Perimeter="<<circleObj.getPerimeter()<<endl; Shape shapeObj; shapeObj.print(); cout<<"Area="<<shapeObj.getArea()<<" Perimeter="<<shapeObj.getPerimeter()<<endl; return 0; }

完成代码如下：

#include <iostream>
#define PI 3.14159
using namespace std;

class Shape {
public:
    virtual void print() {
        cout << "Shape";
    }
    virtual double getArea() {
        return 0;
    }
    virtual double getPerimeter() {
        return 0;
    }
};

class Circle : public Shape {
private:
    double r;
public:
    Circle(double r) {
        this->r = r;
    }
    void print() {
        cout << "Circle: R=" << r;
    }
    double getArea() {
        return PI * r * r;
    }
    double getPerimeter() {
        return 2 * PI * r;
    }
};

class Rectangle : public Shape {
private:
    double width, height;
public:
    Rectangle(double width, double height) {
        this->width = width;
        this->height = height;
    }
    void print() {
        cout << "Rectangle: Width=" << width << ",Height=" << height;
    }
    double getArea() {
        return width * height;
    }
    double getPerimeter() {
        return 2 * (width + height);
    }
};

int main() {
    Rectangle recObj(7.2, 3.5);
    recObj.print();
    cout << "  Area=" << recObj.getArea() << "  Perimeter=" << recObj.getPerimeter() << endl;

    Circle circleObj(2.3);
    circleObj.print();
    cout << "  Area=" << circleObj.getArea() << "  Perimeter=" << circleObj.getPerimeter() << endl;

    Shape shapeObj;
    shapeObj.print();
    cout << "  Area=" << shapeObj.getArea() << "  Perimeter=" << shapeObj.getPerimeter() << endl;

    return 0;
}

输出结果为：

Rectangle: Width=7.2,Height=3.5  Area=25.2  Perimeter=21.4
Circle: R=2.3  Area=16.619  Perimeter=14.4513
Shape  Area=0  Perimeter=0