第三周 项目2 计算旱冰场的造价

#include  <iostream>
using namespace std;
const double Pi=3.1415926;
class Circle
{
public:
void setRadius(double r);	//半径
double area();				//面积
double circumference();		//周长
private:
double radius;
};
void Circle::setRadius(double r)	//半径
{
radius=r;
}
double Circle::area()				//面积
{
return Pi * radius * radius;
}
double Circle::circumference()		//周长
{
return 2*Pi*radius;
}
int main()
{
double r;
cout<<"请输入旱冰场的半径: ";
cin>>r;
Circle c;
c.setRadius(r);
cout<<"旱冰场的造价为 "<<20*c.area()+35*c.circumference()<<" 元。"<<endl;
return 0;
}