#1,026 – Checking a Flagged enum Type for Validity

You normally use the Enum.IsDefined method to check whether a particular enum value is a valid value.  This method does not work on flagged enums.

Assuming the following enum type:

    [Flags]
    public enum Talents
    {
        Singing = 1,
        Dancing = 2,
        Juggling = 4,
        JokeTelling = 8
    };

Enum.IsDefined will not work for all values of the flagged enum:

            Talents myTalent = Talents.JokeTelling | Talents.Juggling;
            // Returns false
            bool isDefCheck = Enum.IsDefined(typeof(Talents), myTalent);

To properly check for validity, you can convert the enum to a string and then try parsing as an integer. If the value is invalid, ToString() will convert to a simple integer and the parse will then succeed.

        private static void CheckTalents(Talents t)
        {
            int intTest;
            if (int.TryParse(t.ToString(), out intTest))
                Console.WriteLine("Talents not ok");
            else
                Console.WriteLine("Talents ok");
        }

1026-001

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About Sean
Software developer in the Twin Cities area, passionate about .NET technologies. Equally passionate about my own personal projects related to family history and preservation of family stories and photos.

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