函数调用求圆面积

#include<stdio.h>

#define Pi 3.14159 

double Square(double r){

   return Pi * r * r;

}

double Perimeter(double r){

   return 2 * Pi * r;

}

int main(){

    double r;

    printf("请输入圆的半径：\n");

    while(scanf("%lf",&r)!= EOF){

        printf("圆的面积是%lf\n",Square(r));

        printf("圆的周长是%lf\n",Perimeter(r));

        printf("请输入圆的半径：\n");

    }

    return 0; //退出

}