8-6定义一个Shape抽象类,在此基础上派生出Rectangle和Circle,二者都有getArea()函数计算对象的面积,getPerim()函数计算对象的周长。
#include <iostream>
using namespace std;
class Shape
{
public:
Shape(){}
~Shape(){}
virtual float getArea() = 0;
virtual float getPerim() = 0;
};
class Rectangle : public Shape
{
public:
Rectangle(float len,float wid):length(len),width(wid){}
~Rectangle(){}
float getArea() {return length * width;}
float getPerim(){return 2*(length + width);}
virtual getlength(){return length;}
virtual getwidth(){return width;}
private:
float length;
float width;
};
class Circle : public Shape
{
public:
Circle(float ri):r(ri){}
~Circle(){}
float getArea() {return 3.14 * r * r;}
float getPerim(){return 2 * 3.14 * r;}
virtual getr(){return r;}
private:
float r;
};
int main()
{
Shape *a;
a = new Rectangle(1,2);
cout << "The area of the Rectangle is " << a->getArea() << endl;
cout << "The perimeter of the Rectangle is " << a->getPerim () << endl;
delete a;
a = new Circle(2);
cout << "The area of the Circle is " << a->getArea () << endl;
cout << "The perimeter of the Circle is " << a->getPerim () << endl;
delete a;
return 0;
}