29常量成员

const 常量

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

namespace yuan
{
    class Program
    {
        static void Main(string[] args)
        {
            yuan y = new yuan(10);
            Console.WriteLine("圆周率{0}",yuan.pi);
            Console.WriteLine("半径{0}", y.r);
            Console.WriteLine("周长{0}", y.ZC());
            Console.WriteLine("面积{0}", y.MJ());
        }
    }
    class yuan
    {
        public int r;
        public const double pi = 3.1415926;//隐式的静态成员
        public yuan(int rValue)
        {
            r = rValue;
        }
        public double ZC()
        {
            return 2 * pi * r;
        }
        public double MJ()
        {
            return pi * r * r;
        }
    }
}

 readonly 声明时可以不赋值。

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

namespace zhidu
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("=====天空酒店=====");
            Hotel skyHotel = new Hotel(140);
            for (int i = 0; i < 141; i++)
            {
                skyHotel.LodgeIn();
            }
            Console.WriteLine("房间总数{0}",skyHotel.roomNumber);
            Console.WriteLine("客人总数{0}", skyHotel.guestNumber);


            Console.WriteLine("=====天空2号酒店=====");
            Hotel skyHotel2 = new Hotel(180);
            for (int i = 0; i < 141; i++)
            {
                skyHotel2.LodgeIn();
            }
            Console.WriteLine("房间总数{0}", skyHotel2.roomNumber);
            Console.WriteLine("客人总数{0}", skyHotel2.guestNumber);
        }
        class Hotel
        {
            public readonly int roomNumber;
            public int guestNumber = 0;
            public Hotel(int roomNumberValue)
            {
                roomNumber = roomNumberValue;
            }
            public bool isFull()
            {
                if (guestNumber >= roomNumber)
                    return true;
                else
                    return false;
            }
            public void LodgeIn()
            {
                if (isFull() == true)
                    Console.WriteLine("对不起不能入住，房间已满！");
                else
                {
                    guestNumber++;
                    Console.WriteLine("入住成功。");
                }
            }
        }
    }
}