示例-用类的继承计算球圆柱圆锥的表面积体积

/*计算球、圆柱和圆锥的表面积和体积*/ #include<iostream> #include<math.h> using namespace std; const double PI=3.1415926; class Circle //圆类 { protected: double r; public: Circle(double radius=0):r(radius){} double Area() { return PI*r*r; //计算圆的面积 } double Volume() { return 0; //计算圆的体积 } }; class Sphere:public Circle //球体类 { public: Sphere(double radius=0):Circle(radius){} double Area() //计算球的表面积 { return 4*PI*r*r;//返回表达式可以用4*Circle::Area()来代替 } double Volume() //计算球的体积 { return 4*PI*pow(r,3)/3; //pow(r,3)求出r的立方值 } }; class Cylinder:public Circle //圆柱体类 { double h; //高度 public: Cylinder(double radius=0,double height=0):Circle(radius) { h=height; } double Area() //计算圆柱体的表面积 { return 2*PI*r*r*h; } double Volume()//计算圆柱体的体积 { return PI*r*r*h;//返回表达式可以用Circle::Area()*h来代替 } }; class Cone:public Circle //圆锥体类 { double h;//高度 public: Cone(double radius=0,double height=0):Circle(radius) { h=height; } double Area() //计算圆锥体的表面积 { double l=sqrt(h*h+r*r);//sqrt函数救出参数值的平方根 return PI*r*(r+1); } double Volume()//计算圆锥体的体积 { return PI*r*r*h/3; } }; void main() { Circle r1(2); Sphere r2(2); Cylinder r3(2,3); Cone r4(2,3); cout<<"Circle: "<<r1.Area()<<' '<<r1.Volume()<<endl; cout<<"Sphere: "<<r2.Area()<<' '<<r2.Volume()<<endl; cout<<"Cylinder: "<<r3.Area()<<' '<<r3.Volume()<<endl; cout<<"Cone: "<<r4.Area()<<' '<<r4.Volume()<<endl; }