C# 枚举

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

namespace ConsoleApplication1
{
    public enum TimeofDay
    {
        Morning,
        Afternoon,
        Evening
    }
    class Program
    {

        static void WriteGreeting(TimeofDay timeofDay)
        {
            switch (timeofDay)
            {
                case TimeofDay.Morning:
                    Console.WriteLine("good morning");
                    break;
                case TimeofDay.Afternoon:
                    Console.WriteLine("good afternoon");
                    break;
                case TimeofDay.Evening:
                    Console.WriteLine("good evening");
                    break;
            }
        }

      
        static void Main(string[] args)
        {
            WriteGreeting(TimeofDay.Morning);
            WriteGreeting(TimeofDay.Evening);
            WriteGreeting(TimeofDay.Afternoon);           
        }     
    }
}