using System;

​

enum Status

{

    M = 1,

    F = 2

}

​

public class Program

{

    public static void Main()

    {

        string gender = "F";//"M", "F", "20"

         var test = Enum.IsDefined(typeof(Status), gender);   // exists = false

​

        Console.WriteLine(test);

    }

}