C# FlagAttriute 的 小妙招

FlagAttriute ，指示可将枚举视为位域（即一组标志）。

官网中文解说：https://docs.microsoft.com/zh-cn/dotnet/api/system.flagsattribute?redirectedfrom=MSDN&view=netframework-4.7.2

以下是对应的demo,可以利用该特性，将业务场景中的角色设定为：1，2，4，8 这种按位操作，再判断是否包含该角色~

 public class EnumDemo
    {
        public static void Test()
        { 
            DirectionEnumType type = (DirectionEnumType)13;

            //可以用来判断是否存在right值
            bool IsExistRigth = ((type & DirectionEnumType.Right) == DirectionEnumType.Right);

            Console.WriteLine(type);

            Console.WriteLine(IsExistRigth);
            Console.WriteLine(1 << 5); //2的5次方  32

             //有对应值的会输出 int - string 数据，没有值的，则输出 int -int数据
            for (int val = 0; val <= 16; val++)
                Console.WriteLine("{0,3} - {1:G}", val, (SingleHue)val);

            Console.WriteLine("--------------------------------");


            //有值的，或者有对应的组合值的，会输出int -string数据，否则输出 int-int 数据
            for (int val = 0; val <= 16; val++)
                Console.WriteLine("{0,3} - {1:G}", val, (MultiHue)val);

            /*
Top, Bottom, Left
False
32
  0 - None
  1 - Black
  2 - Red
  3 - 3
  4 - Green
  5 - 5
  6 - 6
  7 - 7
  8 - Blue
  9 - 9
 10 - 10
 11 - 11
 12 - 12
 13 - 13
 14 - 14
 15 - 15
 16 - 16
 --------------------------------
  0 - None
  1 - Black
  2 - Red
  3 - Black, Red
  4 - Green
  5 - Black, Green
  6 - Red, Green
  7 - Black, Red, Green
  8 - Blue
  9 - Black, Blue
 10 - Red, Blue
 11 - Black, Red, Blue
 12 - Green, Blue
 13 - Black, Green, Blue
 14 - Red, Green, Blue
 15 - Black, Red, Green, Blue
 16 - 16
             */
        }

   [Flags]
    public enum DirectionEnumType
    {
        Top = 1,
        Right = 2,
        Bottom = 4,
        Left = 8,
    }

    enum SingleHue : short
    {
        None = 0,
        Black = 1,
        Red = 2,
        Green = 4,
        Blue = 8
    };

    // Define an Enum with FlagsAttribute.
    [FlagsAttribute]
    enum MultiHue : short
    {
        None = 0,
        Black = 1,
        Red = 2,
        Green = 4,
        Blue = 8
    };