DigitAsWord

using System;

namespace DigitAsWord
{
    class DigitAsWord
    {
        static void Main()
        {
            string inputValue = Console.ReadLine();
            double digit;
            bool parseSuccess = double.TryParse(inputValue, out digit);
            Console.Write(parseSuccess ? inputValue : "{0} not a digit!", inputValue);

            switch (inputValue)
            {
               case "0": Console.WriteLine(" zero"); break;
               case "1": Console.WriteLine(" one"); break;
               case "2": Console.WriteLine(" two"); break;
               case "3": Console.WriteLine(" three"); break;
               case "4": Console.WriteLine(" four"); break;
               case "5": Console.WriteLine(" five"); break;
               case "6": Console.WriteLine(" six"); break;
               case "7": Console.WriteLine(" seven"); break;
               case "8": Console.WriteLine(" eight"); break;
               case "9": Console.WriteLine(" nine"); break;
               default: if ((digit < 0) || (digit > 9))
                   {
                       Console.WriteLine(" not a digit"); ;
                   }
                   break;
            }
        }
    }
}