asp.net4.5练习~test3-3

控制台程序

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace test3_3
{
    class Program
    {
        static void Main(string[] args)
        {
            const double PI = 3.1415926;
            Console.WriteLine("请输入圆的半径：");
            double r = int.Parse(Console.ReadLine());
            double area = r * r * PI;
            Console.WriteLine("圆的面积是{0}",area);
            Console.ReadLine();
        }
    }
}