using System;

namespace Worx.CSharp.Basics
{
    class EnumExample
    {
        public static int Main()
        {
            WriteGreeting(TimeOfDay.Morning);
            return 0;
        }

        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;

                default:
                    Console.WriteLine("hello!");
                    break;
            }
        }
    }
}


这段代码是c#高级编程第四版中的一个例子，编译时TimeOfDay下有一道绿线，不知道要怎么写才能不出错。

是不是少了一个类

TimeOfDay，看样子是个枚举，它在什么地方~

没太明白楼上的意思？能不能说的详细一点，谢谢。

应该事定义的一个类吧

public enum TimeOfDay
{
   Morning,
   .......

}

namespace EnumExample
{
    class Program
    {
        public enum TimeOfDay
        {
            Morning = 0,
            Afternoon = 1,
            Evening =2
        }
        public static int Main()
        {
            WriteGreeting(TimeOfDay.Morning);
            return 0;
        }
        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;
                default:
                    Console.WriteLine("Hello!");
                    break;

            }

            Console.ReadLine();
        }
    }
}
没有定义枚举