C++习题 抽象基类

C++习题 抽象基类

时间: 1ms        内存:128M

描述:

编写一个程序,声明抽象基类Shape,由它派生出3个派生类: Circle(圆形)、Rectangle(矩形)、Triangle(三角形),用一个函数printArea分别输出以上三者的面积(结果保留两位小数),3个图形的数据在定义对象时给定。

输入:

圆的半径
矩形的边长
三角形的底与高

输出:

圆的面积
矩形的面积
三角形的面积

示例输入:

12.6
4.5 8.4
4.5 8.4

示例输出:

area of circle = 498.76
area of rectangle = 37.80
area of triangle = 18.90

提示:

参考答案(内存最优[1092]):

#include<stdio.h>
int main()
{
	float a,b,c,d,e;
	scanf("%f",&a);
	scanf("%f %f",&b,&c);
	scanf("%f %f",&d,&e);
	printf("area of circle = %.2f\n",a*3.1415926535898*a);
	printf("area of rectangle = %.2f\n",b*c);
	printf("area of triangle = %.2f\n",d*e/2);
}

参考答案(时间最优[0]):

#include<iostream>
#include<iomanip>
using namespace std;
class Shape
{
public:
	virtual double Area()=0;
};
class Circle:public Shape
{
public:
	Circle(double R):r(R){}
	virtual double Area()
	{
		return 3.1415926*r*r;
	}
private:
	double r;
};
class Rectangle:public Shape
{
public:
	Rectangle(double a,double b):chang(a),kuan(b){};
	virtual double Area()
	{
		return chang*kuan;
	}
private:
	double chang,kuan;
};
class Triangle:public Shape
{
public:
    Triangle(double a,double b):di(a),gao(b){};
	virtual double Area()
	{
		return di*gao/2;
	}
private:
	double di,gao;
};

void printArea(Shape& shape)
{
    cout<<shape.Area()<<endl;
}
int main()
{
    float r,a,b,w,h;
    cout<<fixed<<setprecision(2);
    cin>>r;
    Circle circle(r);
    cout<<"area of circle = ";
    printArea(circle);
    cin>>a>>b;
    Rectangle rectangle(a,b);
    cout<<"area of rectangle = ";
    printArea(rectangle);
    cin>>w>>h;
    Triangle triangle(w,h);
    cout<<"area of triangle = ";
    printArea(triangle);
    return 0;
}

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