How can I determine if a variable is assigned a value that is present in an Enum?

Question

I have this Enum:

namespace J.Enums
{
    public enum TH
    {
        Light = 0,
        Dark = 1
    }

    public static partial class Extensions
    {
        public static string Text(this TH theme)
        {
            switch (theme)
            {
                default:
                case TH.Light: return "Light";
                case TH.Dark: return "Dark";
            }
        }

        public static TH ToTheme(this string theme)
        {
            switch (theme)
            {
                default:
                case "Light": return TH.Light;
                case "Dark": return TH.Dark;
            }
        }
    }
}

If I have a variable a as follows:

var a = 88;

How can I determine if the value of a is a valid value for the Enum? Which in this case, it won't be.

Use [Enum.TryParse()](https://learn.microsoft.com/en-us/dotnet/api/system.enum.tryparse?view=netframework-4.8)... — Idle_Mind, Apr 25 '19 at 13:28
[Enum.IsDefined](https://learn.microsoft.com/en-us/dotnet/api/system.enum.isdefined?view=netframework-4.8) — 001, Apr 25 '19 at 13:29
Hi Amy, Would it be better to have a different line with default: return TH.Light; I'm not sure if there's any difference but welcome your advice. Thanks — Alan2, Apr 25 '19 at 13:42
Possible duplicate of [Is there a way to check if int is legal enum in C#?](https://stackoverflow.com/questions/2674730/is-there-a-way-to-check-if-int-is-legal-enum-in-c) — Sinatr, Apr 25 '19 at 14:23

score 6 · Accepted Answer · answered Apr 25 '19 at 13:28

6

var isDefined = Enum.IsDefined(typeof(TH), a);

answered Apr 25 '19 at 13:28

Metheny

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Thanks, this works and will accept. Unfortunately I now realise I have another problem but your answer was a big help. I'll write up another question for the next problem I have. – Alan2 Apr 25 '19 at 13:33

How can I determine if a variable is assigned a value that is present in an Enum?

1 Answers1