C++面向对象类的实例题目十二

题目描述：

写一个程序计算正方体、球体和圆柱体的表面积和体积

程序代码：

#include<iostream>
#define PAI 3.1415
using namespace std;
class Shape
{
	public:
		virtual void ShapeName()=0;
		virtual void area()
		{
			return ;
		}
		virtual void volume()
		{
			return ;
		}
};
class Cube:public Shape
{
	public:
		Cube(float len):length(len){};
		void ShapeName()
		{
			cout<<"Cube:"<<endl;
		}
		void area()
		{
			double s = 6*length*length;
			cout<<"Area:"<<s<<endl;
		}
		void volume()
		{
			double v = length*length*length;
			cout<<"Volume:"<<v<<endl;
		}
	private:
		float length;
};
class Sphere:public Shape
{
	public:
		Sphere(float r):radius(r){};
		void ShapeName()
		{
			cout<<"Sphere:"<<endl;
		}
		void area()
		{
			double s = 4*radius*radius*PAI;
			cout<<"Area:"<<s<<endl;
		}
		void volume()
		{
			double v = (4*radius*radius*radius*PAI)/3;
			cout<<"Volume:"<<v<<endl;
		}
	private:
		float radius;
};
class Cylinder:public Shape
{
	public:
		Cylinder(float r,float h):radius(r),length(h){};
		void ShapeName()
		{
			cout<<"Cylinder:"<<endl;
		}
		void area()
		{
			double s = radius*radius*PAI + 2*PAI*radius*length;
			cout<<"Area:"<<s<<endl;
		}
		void volume()
		{
			double v = radius*radius*PAI*length;
			cout<<"Volume:"<<v<<endl;
		}
	private:
		float radius;
		float length;
};
int main()
{
	Shape * pt;
	pt = new Cube(2);
	pt->ShapeName();
	pt->area();
	pt->volume();
	cout<<"==========================="<<endl;
	pt = new Sphere(2);
	pt->ShapeName();
	pt->area();
	pt->volume();
	cout<<"==========================="<<endl;
	pt = new Cylinder(2,2);
	pt->ShapeName();
	pt->area();
	pt->volume();
	cout<<"==========================="<<endl; 
} 

结果输出：

Cube:
Area:24
Volume:8
===========================
Sphere:
Area:50.264
Volume:33.5093
===========================
Cylinder:
Area:37.698
Volume:25.132
===========================