题目要求如下:
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代码如下:
/*
* Copyright (c) 2013, 烟台大学计算机学院
* All rights reserved.
* 作 者: 沈远宏
* 完成日期:2014 年06月19日
* 版 本 号:v1.0
* 问题描述:Description
编写一个程序,定义抽象基类Shape,由它派生出5个派生类: Circle(圆形)、Square(正方形)、Rectangle(矩形)、Trapezoid(梯形)、Triangle(三角形)。
用虚函数分别计算几种图形面积,并求它们之和。
要求用基类指针数组,使它每一个元素指向一个派生类对象。
Input
圆的半径
正方形的边长
矩形的边长
梯形的上底和下底,高
三角形的底与高
Output
所有图形面积之和(结果保留两位小数)
*/#include <iostream>
#include <iomanip>
#define PI 3.1415926
using namespace std;
class Shape
{
public:
virtual double area()=0;
};
class Circle:virtual public Shape
{
protected:
double r;
double c_area;
public:
Circle(double rr):r(rr){}
double area()
{
return c_area=PI*r*r;
}
};
class Rectangle:virtual public Shape
{
protected:
double width;
double length;
double c_area;
public:
Rectangle(double ww,double ll):width(ww),length(ll){}
double area()
{
c_area=width*length;
return c_area;
}
};
class Triangle:virtual public Shape
{
protected:
double width;
double height;
double c_area;
public:
Triangle(double ww,double hh):width(ww),height(hh){}
double area()
{
c_area=width*height/2;
return c_area;
}
};
class Square:virtual public Shape
{
protected:
double length;
double c_area;
public:
Square(double ll):length(ll){}
double area()
{
c_area=length*length;
return c_area;
}
};
class Trapezoid:virtual public Shape
{
protected:
double length_s;
double length_x;
double height;
double c_area;
public:
Trapezoid(double ss,double xx,double hh):length_s(ss),length_x(xx),height(hh){}
double area()
{
c_area=(length_s+length_x)*height/2;
return c_area;
}
};
//主函数已给定如下,提交时不需要包含,会自动添加到程序尾部
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;
}
运行结果:
OJ要求结果输出例样: