第十三周实验报告3

/* (程序头部注释开始)
* 程序的版权和版本声明部分
* Copyright (c) 2012, 烟台大学计算机学院学生
* All rights reserved.
* 文件名称：Shape抽象类
* 作 者： 于宸
* 完成日期： 2012 年 05 月 20 日
* 版 本 号： 1.067
* 对任务及求解方法的描述部分
* 输入描述： ......
* 问题描述： ......
* 程序输出： ......
* 程序头部的注释结束
*/

#include<iostream>
using namespace std;
const double PI = 3.14159;
class Shape
{
public:
virtual double area() const =0;
};

class Circle: public Shape
{
public:
Circle(double radius);
virtual double area() const;
protected:
double radius;                                                 //半径
};

class Rectangle: public Shape
{
public:
Rectangle(double length, double width);
virtual double area() const;
protected:
double length;
double width;
};

class Triangle: public Shape
{
public:
Triangle(double base, double height);
virtual double area() const;
protected:
double base;
double height;
};

Circle::Circle(double radius)
{
this->radius = radius;
}

double Circle::area() const
{
return PI * radius * radius;
}

Rectangle::Rectangle(double length, double width)
{
this->length = length;
this->width = width;
}

double Rectangle::area() const
{
return length * width;
}
Triangle::Triangle(double base, double height)
{
this->base = base;
this->height = height;
}

double Triangle::area() const
{
return 0.5 * base * height;
}

int main()
{
Circle c1(12.6), c2(4.9);    //建立Circle类对象c1,c2,参数为圆半径
Rectangle r1(4.5, 8.4), r2(5.0, 2.5);       //建立Rectangle类对象r1,r2,参数为矩形长、宽
Triangle t1(4.5, 8.4), t2(3.4, 2.8);    //建立Triangle类对象t1,t2，参数为三角形底边长与高
Shape *pt[6] = {&c1, &c2, &r1, &r2, &t1, &t2}; //定义基类指针数组pt，各元素指向一个派生类对象
double areas = 0.0;      //areas为总面积
for(int i = 0; i < 6; i++)
{
areas = areas + pt[i]->area();
}

cout << "totol of all areas=" << areas << endl;   //输出总面积
system("pause");
return 0;
}