OJ7

/*
* 程序的版权和版本声明部分
* Copyright (c)2013, 烟台大学计算机学院学生
* All rightsreserved.
* 文件名称：.cpp
* 作 者:刘晓晓
* 完成日期：2013 年6月10日
* 版本号： v1.0
* 对任务及求解方法的描述部分：略
* 输入描述：略
* 问题描述：略
*/#include <iostream>
#include <iomanip>
using namespace std;
const double PI =3.1415926;
class Shape
{
public:
    virtual double area() const=0;//纯虚函数
};
class Circle:public Shape
{
public:
    Circle(double r1):r(r1) {}  //结构函数
    virtual double area() const
    {
        return PI*r*r;
    };   //定义虚函数
protected:
    double r;

};
class Triangle:public Shape
{
public:
    Triangle(double w,double h):width(w),height(h) {}
    virtual double area() const
    {
        return (width*height)/2;
    }
protected:
    double width,height;
};
class Rectangle:public Shape
{
public:
    Rectangle(double w,double h ):width(w),height(h) {}
    virtual double area() const
    {
        return (width*height);
    }
protected:
    double width,height;
};
class Square :public Shape
{
public :
Square(double l):length(l){}
virtual double area()const
{

   return (length*length);



}

protected:
double length;

};
class Trapezoid:public Shape
{
  public :
  Trapezoid(double h,double l1,double l2):height(h),length1(l1),length2(l2){}
  virtual double area()const
  {
      return (length1+length2)*height/2;


  }
  private:
  double height ,length1,length2  ;


};
int main()


{


    float r,a,b,w1,w2,w,h;


    cout<<fixed<<setprecision(2);


    cin>>r;


    Circle circle(r);


    cin>>a;


    Square square(a);


    cin>>a>>b;


    Rectangle rectangle(a,b);


    cin>>w1>>w2>>h;


    Trapezoid trapezoid(w1,w1,h);


    cin>>w>>h;


    Triangle triangle(w,h);


    Shape *pt[5]= {&circle,&square,&rectangle,&trapezoid,&triangle};


    double areas=0.0;


    for(int i=0; i<5; i++)


        areas=areas+pt[i]->area();


    cout<<"total of all areas="<<areas<<endl;


    return 0;


}