4.试写出所能想到的所有形状（包括二维的和三维的），生成一个形状层次类结构。生成的层次结构一Shape作为基类，并由此派生出TwoDimShape类和ThreeDimShape类。它们的派生类是不同形状类，定义层次结构中的每一个类，并用函数main（）进行测试。

以下是形状层次类结构的代码实现：

#include <iostream>

using namespace std;

class Shape {
public:
    virtual double getArea() = 0;
    virtual double getVolume() = 0;
};

class TwoDimShape : public Shape {
public:
    virtual double getArea() = 0;
};

class ThreeDimShape : public Shape {
public:
    virtual double getArea() = 0;
    virtual double getVolume() = 0;
};

class Circle : public TwoDimShape {
private:
    double radius;
public:
    Circle(double r) : radius(r) {}
    double getArea() {
        return 3.14 * radius * radius;
    }
};

class Square : public TwoDimShape {
private:
    double side;
public:
    Square(double s) : side(s) {}
    double getArea() {
        return side * side;
    }
};

class Rectangle : public TwoDimShape {
private:
    double length, width;
public:
    Rectangle(double l, double w) : length(l), width(w) {}
    double getArea() {
        return length * width;
    }
};

class Sphere : public ThreeDimShape {
private:
    double radius;
public:
    Sphere(double r) : radius(r) {}
    double getArea() {
        return 4 * 3.14 * radius * radius;
    }
    double getVolume() {
        return 4.0 / 3.0 * 3.14 * radius * radius * radius;
    }
};

class Cylinder : public ThreeDimShape {
private:
    double radius, height;
public:
    Cylinder(double r, double h) : radius(r), height(h) {}
    double getArea() {
        return 2 * 3.14 * radius * height + 2 * 3.14 * radius * radius;
    }
    double getVolume() {
        return 3.14 * radius * radius * height;
    }
};

class Cube : public ThreeDimShape {
private:
    double side;
public:
    Cube(double s) : side(s) {}
    double getArea() {
        return 6 * side * side;
    }
    double getVolume() {
        return side * side * side;
    }
};

int main() {
    Circle c(5);
    Square s(4);
    Rectangle r(3, 5);
    Sphere sp(4);
    Cylinder cy(4, 6);
    Cube cu(5);

    cout << "Circle area = " << c.getArea() << endl;
    cout << "Square area = " << s.getArea() << endl;
    cout << "Rectangle area = " << r.getArea() << endl;
    cout << "Sphere area = " << sp.getArea() << ", volume = " << sp.getVolume() << endl;
    cout << "Cylinder area = " << cy.getArea() << ", volume = " << cy.getVolume() << endl;
    cout << "Cube area = " << cu.getArea() << ", volume = " << cu.getVolume() << endl;

    return 0;
}

在这个实现中，我们首先定义了一个基类 Shape，其中包含了两个纯虚函数 getArea 和 getVolume，分别用于计算形状的面积和体积。然后我们定义了两个派生类 TwoDimShape 和 ThreeDimShape，用于区分二维形状和三维形状。接着我们定义了具体的形状类，包括 Circle、Square、Rectangle、Sphere、Cylinder 和 Cube，它们分别继承了 TwoDimShape 或 ThreeDimShape，并实现了相应的计算面积和体积的函数。最后在主函数中，我们创建了不同的形状对象，并调用它们的函数进行计算和输出。