Invoke default case in switch c#

Question

For example let i have something like this.

public enum CarEnum { BWM, LadaKalina };

    class Program
    {
        static void Main(string[] args)
        {
            var carEnum = CarEnum.LadaKalina;
            GetMessage(carEnum);
        }
        public static void GetMessage(CarEnum carEnum)
        {
            switch (carEnum)
            {
                case CarEnum.BWM:
                    Console.WriteLine("BWM");
                    break;
                case CarEnum.LadaKalina:
                    Console.WriteLine("LadaKalina");
                    break;
                default:
                    Console.WriteLine("default");
                    break;
            }
        }
    }

I want to Invoke default case in function GetMessage. What it's better to pass like argument?

Answer 1

I'd provide an enum value that can be used as default/unknown:

public enum CarEnum { Unknown, BWM, LadaKalina };

GetMessage(CarEnum.Unknown);

Answer 2

It's a common convention to add a None enum value to indicate none of the values in the enum:

public enum CarEnum { None, BWM, LadaKalina };

And use it like:

GetMessage(CarEnum.None);

Answer 3

You can do something like this:

GetMessage((CarEnum)-1);

EDIT:

Base on Marc Gravell's comment on other answer I've tested and you could use

        CarEnum? car = null;

        switch (car)
        {
            case CarEnum.BWM:
                break;
            default:
                Console.WriteLine("Default");
                break;
        }