C#语言知识点整理 - 枚举

发布时间：2020-06-12 08:23:12 作者：勇闯天涯X
来源：网络阅读：451

一、枚举定义：

enum 关键字用于声明枚举，即一种由一组称为枚举数列表的命名常量组成的独特类型。

二、枚举规则：

1. 默认情况下，第一个枚举数的值为 0，后面每个枚举数的值依次递增 1；也可强制元素序列从设定值而不是 0 开始

2. 准许使用的枚举类型有 byte、sbyte、short、ushort、int、uint、long 或 ulong。

3. 枚举类型作为位标志，应用 System.FlagsAttribute 特性，每个值都是 2 的若干次幂，可以对这些值执行 AND、OR、NOT 和 XOR 按位运算；避免标志指定零值。

三、枚举例子:

   1: using System;

   2: using System.Collections.Generic;

   3: using System.Linq;

   4: using System.Text;

5:

   6: namespace CSharp.Enum

   7: {

8:

   9:     [Flags]

  10:     enum Days2

  11:     {

  12:         None = 0x0,

  13:         Sunday = 0x1,

  14:         Monday = 0x2,

  15:         Tuesday = 0x4,

  16:         Wednesday = 0x8,

  17:         Thursday = 0x10,

  18:         Friday = 0x20,

  19:         Saturday = 0x40

  20:     }

21:

  22:     class Program

  23:     {

  24:         static void Main(string[] args)

  25:         {

  26:             // Initialize with two flags using bitwise OR.

  27:             Days2 meetingDays = Days2.Tuesday | Days2.Thursday | Days2.Friday;

  28:             Console.WriteLine("Meeting days are {0}", meetingDays);

29:

  30:             // Remove a flag using bitwise XOR.

  31:             meetingDays = meetingDays ^ Days2.Tuesday;

  32:             Console.WriteLine("Meeting days are {0}", meetingDays);

33:

  34:             //若要确定是否设置了特定标志，请使用按位 AND 运算

  35:             bool test = (meetingDays & Days2.Thursday) == Days2.Thursday;

  36:             Console.WriteLine("Thursday {0} a meeting day.", test == true ? "is" : "is not");

37:

  38:             string saturday=System.Enum.GetName(typeof(Days2), 0x40);

  39:             Console.WriteLine("0x40 's Name is {0}",saturday);

40:

  41:             Console.WriteLine("The values of the Days2 Enum are:");

  42:             foreach (int i in System.Enum.GetValues(typeof(Days2)))

  43:             {

  44:                 Console.WriteLine(i);

  45:             }

46:

  47:             Console.WriteLine("The names of the Days2 Enum are:");

  48:             foreach (string str in System.Enum.GetNames(typeof(Days2)))

  49:                 Console.WriteLine(str);

50:

  51:             Days2 saturday2= (Days2)System.Enum.Parse(typeof(Days2), "Saturday");

  52:             if(System.Enum.IsDefined(typeof(Days2),saturday2))

  53:             {

  54:                 Console.WriteLine(" \"Saturday\" 转换为对象 Days2.Saturday ");

  55:             }

56:

  57:         }

  58:     }

  59: }

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