C++求圆面积和周长

重温一下小学知识，求圆面积和周长

c=πd=2πr 圆的周长=直径×圆周率
s=πrr 圆的面积=半径×半径×圆周率

C++代码实现

#include<iostream>
using namespace std;
const float PI=3.141593;

class Circle 
{
private :
	 float radius;
public:
	Circle(float r);
	Circle(Circle &C);
	float Area();
	float Girth();

};

Circle::Circle(float r)
{
	radius=r;
}

float Circle::Area()
{
	return PI*radius*radius;
}

float Circle::Girth()
{
	return 2*PI*radius;
}


void main()
{
	float radius ;
	cin>>radius;
	Circle Yuan(radius);
	cout<<"面积："<<Yuan.Area()<<endl;
	cout<<"周长："<<Yuan.Girth()<<endl;
}