Enum-flags

Flags: allow an enum value to contain many values. An enum type with the [Flags] attribute can have multiple constant values assigned to it. And it is still possible to test for these values in switches and if-statements. This is an attribute that tells .NET to allow you to assign the enum with bitwise operators. 

Enum values. The values 0x0, 0x1, 0x2, 0x4 and so on indicate powers of two. In computer bits, powers of two contain one bit set, moving from the first bit to the final bit. You could use the decimal values, 0, 1, 2, 4, 8... instead.

Example. The [Flags] attribute on an enum allows you to assign multiple values to your enum at once. You can do this with bitwise manipulations, meaning you can store an enum with A and C set, not just A and not just C.

using System;

class Program
{
    [Flags]
    enum RenderType
    {
       None = 0x0,
       DataUri = 0x1,
       GZip = 0x2,
       ContentPage = 0x4,
       ViewPage = 0x8,
       HomePage = 0x10 // Next two values could be 0x20, 0x40
    }

    static void Main()
    {
 // 1.
 // Set the first type.
 RenderType type1 = RenderType.ContentPage;

 // 2.
 // Set the second type if the condition matches.
 if (true)
 {
     type1 |= RenderType.GZip;
 }

 // 3.
 // Check the enum flags.
 Check(type1);

 // 4.
 // Set a new enum in three statements.
 RenderType type2 = RenderType.ViewPage;
 type2 |= RenderType.DataUri;
 type2 |= RenderType.GZip;

 // 5.
 // See if the enum contains this flag.
 if ((type2 & RenderType.DataUri) == RenderType.DataUri)
 {
     Console.WriteLine("True");
 }

 // 6.
 // See if the enum contains this flag.
 if ((type2 & RenderType.ContentPage) == RenderType.ContentPage)
 {
     throw new Exception();
 }

 // 7.
 // Check the enum flags.
 Check(type2);
    }

    static void Check(RenderType type)
    {
 // Switch on the flags.
 switch (type)
 {
     case RenderType.ContentPage | RenderType.DataUri | RenderType.GZip:
  {
      Console.WriteLine("content, datauri, gzip");
      break;
  }
     case RenderType.ContentPage | RenderType.GZip: // < first match
  {
      Console.WriteLine("content, gzip");
      break;
  }
     case RenderType.ContentPage:
  {
      Console.WriteLine("content");
      break;
  }
                // < second match
     case RenderType.ViewPage | RenderType.DataUri | RenderType.GZip: 
  {
      Console.WriteLine("view, datauri, gzip");
      break;
  }
     case RenderType.ViewPage | RenderType.GZip:
  {
      Console.WriteLine("view, gzip");
      break;
  }
     case RenderType.ViewPage:
  {
      Console.WriteLine("view");
      break;
  }
     case RenderType.HomePage | RenderType.DataUri | RenderType.GZip:
  {
      Console.WriteLine("home, datauri, gzip");
      break;
  }
     case RenderType.HomePage | RenderType.GZip:
  {
      Console.WriteLine("home, gzip");
      break;
  }
     case RenderType.HomePage:
  {
      Console.WriteLine("home");
      break;
  }
 }
    }
}

Output

content, gzip
True
view, datauri, gzip

The "|" operator is used in the cases. This simply means the values are combined.

refer link: http://www.dotnetperls.com/enum-flags