Question

定义一个抽象类shape，包括公有的计算面积area函数，计算体积volume函数，输出基本信息函

定义一个抽象类shape，包括公有的计算面积area函数，计算体积volume函数，输出基本信息函数printinfo（三个函数均为纯虚函数）。从shape公有派生point类，增加私有数据成员x,y坐标，以及构造函数，析构函数。从point公有派生circle类，增加私有数据成员半径r，以及构造函数，析构函数。从circle公有派生cylinder类，增加私有数据成员高度h，以及构造函数，析构函数。（在定义三个派生类的过程中，自己考虑需要重定义哪个虚函数）。在main函数中，定义shape类的指针，指向派生类的对象，输出三类对象的基本信息，面积，体积；（将shape指针改为引用再尝试）。
不要复制哦

Answer 1

参考下面代码
#include <iostream>
#define pi 3.14

using namespace std;

class Shape
{
protected:
double Area;
public:
virtual void area() = 0;
void showArea(){cout << Area << endl;}
};

class Circle : public Shape
{
double r;
public:
Circle(int r){this->r = r;}
virtual void area(){Area = pi * r * r;}
};

class Rectangle : public Shape
{
double l, w;
public:
Rectangle(int l, int w){this->l = l, this->w = w;}
virtual void area(){Area = l * w;};
};

class Triangle : public Shape
{
double a, b;
public:
Triangle(int a, int b){this->a = a, this->b = b;}
virtual void area(){Area = a * b / 2.0;}
};

void disPlay()
{
cout << "Please input a number:" << endl;
cout << "1. Circle" << endl;
cout << "2. Rectangle" << endl;
cout << "3. Triangle" << endl;
}
int main()
{
int n, num = 0;
int r, l, w, a, b;
cout << "Please input the number of shape:" << endl;
cin >> n;
Shape *temp[100];

disPlay();
while (n--)
{
int elect;
cin >> elect;
switch(elect)
{
case 1:
cout << "Please input r:" << endl;
cin >> r;
temp[num++] = new Circle(r);
break;
case 2:
cout << "Please input l and w:" << endl;
cin >> l >> w;
temp[num++] = new Rectangle(l, w);
break;
case 3:
cout << "Please input a and b:" << endl;
cin >> a >> b;
temp[num++] = new Triangle(a, b);
break;
defult:
cout << "error!" << endl;
}
}

for (int i = 0; i < num; i++)
{
temp[i]->area();
temp[i]->showArea();
}
return 0;
}