实验12：Problem B: 图形计数与求面积

#include<iostream>
#include<iomanip>

using namespace std;
class Shape{
public:
    static int num;
    Shape(){num++;cout<<"A shape is created!"<<endl;}
    virtual ~Shape(){cout<<"A shape is erased!"<<endl;}
    static int getNumOfShapes(){return num;}
    virtual double getArea()=0;
};

class Circle: public Shape{
public:
    double r;
    static int num1;
    Circle(double a=0):r(a){num1++;cout<<"A circle is created!"<<endl;}
    ~Circle(){cout<<"A circle is erased!"<<endl;}
    double getArea(){return 3.14*r*r;}
    static int getNumOfCircles(){return num1;}
};
class Square:public Shape{
public:
    double s;
    static int num2;
    Square(double a=0):s(a){num2++;cout<<"A square is created!"<<endl;}
    ~Square(){cout<<"A square is erased!"<<endl;}
    double getArea(){return s*s;}
    static int getNumOfSquares(){return num2;}
};
int Shape::num=0;
int Circle::num1=0;
int Square::num2=0;
int main()
{
    int cases;
    char type;
    double data;
    Shape *shape;
    cin>>cases;
    cout<<"numOfShapes = "<<Shape::getNumOfShapes();
    cout<<", numOfCircles = "<<Circle::getNumOfCircles();
    cout<<", numOfSquares = "<<Square::getNumOfSquares()<<endl;
    for (int i = 0; i < cases; i++)
    {
        cin>>type>>data;
        switch(type)
        {
        case ‘C‘:
            shape = new Circle(data);
            break;
        case ‘S‘:
            shape = new Square(data);
            break;
        }
        cout<<"Area = "<<setprecision(2)<<fixed<<shape->getArea()<<endl;
        delete shape;
    }
    cout<<"numOfShapes = "<<Shape::getNumOfShapes();
    cout<<", numOfCircles = "<<Circle::getNumOfCircles();
    cout<<", numOfSquares = "<<Square::getNumOfSquares()<<endl;
}