继承，虚函数应用，对象向量

#include #include #include #include #include #define PI 3.1416using namespace std;class Shape//定义抽象基类{public:    Shape() {}//构造函数    virtual double GetArea() const =0;//纯虚函数    virtual ~Shape() {}//虚析构函数};double TotalArea(const vector & p)//求面积和{    double total=0;    for(int i=0;iGetArea();    return total;}class Circle : public Shape//圆继承基类shape{private:    double radius;//半径public:    Circle(double r) : radius(r) {}//构造函数，初始化半径    virtual double GetArea() const//返回圆的面积    {        return radius * radius * PI;    }};class Rectangle : public Shape//长方形继承基类shape{private:    double height;//定义长    double width;//定义宽public:    Rectangle(double h, double w) : height(h), width(w) {}//构造函数，初始化长和宽    virtual double GetArea() const//返回长方形的面积    {        return height * width;    }};class Triangle : public Shape//三角形继承基类shape{private:    double a, b, c;//定义边长    double p;//海伦公式public:    Triangle(double A, double B, double C) : a(A), b(B), c(C)//构造函数，初始化边长    {        p = (a + b + c) / 2;    }    virtual double GetArea() const//返回三角形的面积    {        return sqrt(p * (p - a) * (p - b) * (p - c));    }};int main(){    string order;//预处理命令    vector p;//抽象基类指针    double radius, height, width, a, b, c;//定义基本变量    while (cin >> order) {        char Ord;//实际命令        if (order == "circle")            Ord = 'c';        if (order == "rectangle")            Ord = 'r';        if (order == "triangle")            Ord = 't';        switch (Ord) {            case 'c':                cin >> radius;                p.push_back(new Circle(radius));                break;            case 'r':                cin >> height >> width;                p.push_back(new Rectangle(height, width));                break;            case 't':                cin >> a >> b >> c;                p.push_back(new Triangle(a, b, c));                break;            default:                break;        }    }    cout.precision(4);    cout << fixed << TotalArea(p) << endl;    for(int i=0;i