//圆的面积 S =PI*R*R
const double PI = 3.1415926;//常量使用const定义 常量名大写
Console.WriteLine("请输入圆的半径");
int r;
r=int.Parse(Console.ReadLine());
double s = PI * r * r;
Console.WriteLine(r + "的面积是:" + s);
Console.ReadLine();
来源:CSDN
作者:白方圆
链接:https://blog.csdn.net/jacky__wang/article/details/104600375