1.设计一个抽象类Shape。在此基础上派生出类Triangle和Circle，两者都有计算对象面积的函数GetArea和计算对象周长的函数GetPerim。编写测试程序程序：

#include<iostream>

#include <iostream>

using namespace std;

class shape

{

public:

    virtual void getarea() = 0;

    virtual void getperim() = 0;

    virtual void set() = 0;

    virtual void display() = 0;

};

class triangle :public shape

{

public:

    double a,b,c,p;

    double area, perim;

    void set();

    void getperim();

    void getarea();

    void display();

};

void triangle::set()

{

    cout << "请输入三角形三条边长度" << endl;

    cin >> a >> b >> c;

}

void triangle::getperim()

{

    perim = a + b + c;

}

void triangle::getarea()

{

    p = (a + b + c) / 2;

    area = sqrt(p * (p - a) * (p - b) * (p - c));

}

void triangle::display()

{

    cout << "三角形周长为" << perim << endl;

    cout << "三角形面积为" << area << endl;

}

class circle :public shape

{

public:

    double r;

    double area, perim;

    void set();

    void getperim();

    void getarea();

    void display();

};

void circle::set()

{

    cout << "请输入圆的半径" << endl;

    cin >> r;

}

void circle::getperim()

{

    perim = 2 * r * 3.14;

}

void circle::getarea()

{

    area = r * r * 3.14;

}

void circle::display()

{

    cout << "圆形形周长为" << perim << endl;

    cout << "圆形形面积为" << area << endl;

}

int main()

{

    shape* shape[2];

    shape[0] = new triangle();

    shape[1] = new circle();

    for (int i = 0; i < 2; i++) {

         shape[i]->set();

         shape[i]->getarea();

         shape[i]->getperim();

         shape[i]->display();

    }

         return 0;

}