C#: Flags attribute

Flags attribute indicates that an enumeration can be treated as bit fields (Set of flags).

    [Flags]

    enum DaysWithFlags

    {

        SUNDAY = 1,

        MONDAY = 2,

        TUESDAY = 4,

        WEDNESDAY = 8,

        THRUSDAY = 16,

        FRIDAY = 32,

        SATURDAY = 64

    }

Note that [Flags] by itself doesn't change this at all - all it does is enable a nice representation by the .ToString() method

String result1 = (DaysWithFlags.MONDAY | DaysWithFlags.TUESDAY | DaysWithFlags.WEDNESDAY | DaysWithFlags.THRUSDAY | DaysWithFlags.FRIDAY).ToString();

‘result1’ has the value "MONDAY, TUESDAY, WEDNESDAY, THRUSDAY, FRIDAY".

If you don’t specify the [Flags] attribute on enum type, the | operator performs bit wise or and toString method return the result of bitwise or’s of the enum constants.

Following is the working application.

Program.cs

using System;

class Program
{
    [Flags]
    enum DaysWithFlags
    {
        SUNDAY = 1,
        MONDAY = 2,
        TUESDAY = 4,
        WEDNESDAY = 8,
        THRUSDAY = 16,
        FRIDAY = 32,
        SATURDAY = 64
    }

    enum DaysWithOutFlags
    {
        SUNDAY = 1,
        MONDAY = 2,
        TUESDAY = 4,
        WEDNESDAY = 8,
        THRUSDAY = 16,
        FRIDAY = 32,
        SATURDAY = 64
    }


    static void Main()
    {
        String resultWithFlags = (DaysWithFlags.MONDAY | DaysWithFlags.TUESDAY | DaysWithFlags.WEDNESDAY | DaysWithFlags.THRUSDAY | DaysWithFlags.FRIDAY).ToString();

        String resultWithoutFlags = (DaysWithOutFlags.MONDAY | DaysWithOutFlags.TUESDAY | DaysWithOutFlags.WEDNESDAY | DaysWithOutFlags.THRUSDAY | DaysWithOutFlags.FRIDAY).ToString();

        Console.WriteLine("resultWithFlags {0}", resultWithFlags);
        Console.WriteLine("resultWithoutFlags {0}", resultWithoutFlags);
    }

}

Output

resultWithFlags MONDAY, TUESDAY, WEDNESDAY, THRUSDAY, FRIDAY
resultWithoutFlags 62

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