#ifndef CIRCLE_H
#define CIRCLE_H

#include <iostream>

using namespace std;

#define PI 3.14

class Circle
{
private:
    double r;//半径
public:
    Circle();//构造函数
    Circle(double R);//构造函数
    double Area();//求面积函数
};

Circle::Circle()
{
    this->r=5.0;
}

Circle::Circle(double R)
{
    this->r=R;
}

double Circle::Area()
{
    return PI*r*r;

}


#endif