C# Flags Enumeration Helper

Working in the confines of .NET 2.0 (no extension methods), I was in dire need of a helper that would assist in the checking and manipulating of flags enumerations. Over the years that I have used them, I've been bitten enough times using the wrong operators and having to deal with other people maintaining my code that used these enumerations that I finally wrote an enum helper.

This helper covers the setting, checking, and evaluating the flags that have been set on the enum. I wanted to share it with y'all to save you a little of the grief that I have borne. Here it is:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Diagnostics;

namespace TestFlags

{

class Program

{

[Flags]

public enum Flags

{

None = 0,

First = 1,

Second = 2,

Third = 4

}

static void Main(string[] args)

{

var flag = Flags.None;

Debug.Assert(Enum.EnumHasFlag(flag, Flags.Second));

Debug.Assert(Enum.EnumHasFlag(flag, Flags.Third));

List allFlags = Enum.GetFlagEnumList(flag);

foreach (var allFlag in allFlags)

{

Console.WriteLine(allFlag);

}

Console.ReadKey();

}

}

///

/// Assists with enum operations

///

/// The type of the enum.

public static class Enum where TEnum : struct

{

///

/// Adds the specified flag to an enum.

///

/// The append to.

/// To append.

public static void AddFlagToEnum(ref TEnum appendTo, TEnum toAppend)

{

int appendToInt = Convert.ToInt32(appendTo);

int toAppendInt = Convert.ToInt32(toAppend);

appendTo = (TEnum)(object)(toAppendInt | appendToInt);

}

///

/// Determines whether the enum has a certain flag

///

/// The flags enum value to check to see if it contains the checkAgainst value.

/// The flags enum value to check against.

/// whether the enum contains a certain flag

public static bool EnumHasFlag(TEnum toCheck, TEnum checkAgainst)

{

int checkAgainstInt = Convert.ToInt32(checkAgainst);

int toCheckInt = Convert.ToInt32(toCheck);

return (checkAgainstInt & toCheckInt) == checkAgainstInt;

}

///

/// Gets the flag enum list.

///

/// The flags.

/// The list of enum values contained in the flag

public static List GetFlagEnumList(TEnum flags)

{

List result = new List();

var enumValues = (TEnum[])Enum.GetValues(typeof(TEnum));

foreach (var enumValue in enumValues)

{

if (Convert.ToInt32(enumValue) != 0 && EnumHasFlag(flags, enumValue))

{

result.Add(enumValue);

}

}

return result;

}

}

}