6-5

来源：互联网发布：软件模块设计文档编辑：程序博客网时间：2024/06/04 17:59

#include <iostream.h>class Shape{public:virtual double area()const =0;};class Circle:public Shape{public:Circle(double r):radius(r){}virtual double area() const{ return 3.1415*radius*radius;}protected:double radius;};class Rectangle :public Shape{public:Rectangle(double l,double w):length(l),width(w){}virtual double area()const{ return length*width;}protected:double length;double width;};class Triangle:public Shape{public:Triangle(double d,double h):dibian(d),height(h){}virtual double area() const{ return 0.5*dibian*height;}protected:double dibian;double height;};class Square:public Shape{public:Square(double s):side(s){}virtual double area() const{ return side*side;}protected:double side;};class Trapezoid:public Shape{public:Trapezoid(double t,double b,double h):top(t),bottem(b),height(h){}virtual double area() const{ return 0.5*(top+bottem)*height;}protected:double top,bottem,height;};void display(const Shape &s){ cout<<s.area()<<endl;}int main(){ Circle c(4); Rectangle r(2,4); Triangle t(1,2); Square s(2); Trapezoid tt(1,2,3); Shape *p[5]={&c,&r,&t,&s,&tt}; double area=0.0; for(int i=0;i<5;i++) {  area=area+p[i]->area(); } cout<<"the sum of area is "<<area<<endl; return 0;}

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