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
===========================