Question

Why is this even possible? Is it a bug?

using System;

public class InvalidEnumParse
{
    public enum Number
    {
        One,
        Two,
        Three,
        Four
    }

    public static void Main()
    {
        string input = "761";
        Number number = (Number)Enum.Parse(typeof(Number), input);
        Console.WriteLine(number); //outputs 761
    }
}

Answer 1

That’s just the way enums work in .NET. The enum isn’t a restrictive set of values, it’s really just a set of names for numbers (and a type to collect those names together) – and I agree that’s a pain sometimes.

If you want to test whether a value is really defined in the enum, you can use Enum.IsDefined after parsing it. If you want to do this in a more type-safe manner, you might want to look at my Unconstrained Melody project which contains a bunch of constrained generic methods.