Number_as_Words

using System;

namespace Number_as_Words
{
    class MainClass
    {
        static string ContainerOfNumbers(string pointer)
        {
            string convert = "error";

            switch (pointer)
            {
                case "0": convert = "zero";
                    break;
                case "1": convert = "one";
                    break;
                case "2": convert = "two";
                    break;
                case "3": convert = "three";
                    break;
                case "4": convert = "four";
                    break;
                case "5": convert = "five";
                    break;
                case "6": convert = "six";
                    break;
                case "7": convert = "seven";
                    break;
                case "8": convert = "eight";
                    break;
                case "9": convert = "nine";
                    break;
                case "10": convert = "ten";
                    break;
                case "11": convert = "eleven";
                    break;
                case "12": convert = "twelve";
                    break;
                case "13": convert = "thirteen";
                    break;
                case "14": convert = "fourteen";
                    break;
                case "15": convert = "fifteen";
                    break;
                case "16": convert = "sixteen";
                    break;
                case "17": convert = "seventeen";
                    break;
                case "18": convert = "eighteen";
                    break;
                case "19": convert = "nineteen";
                    break;
                case "20": convert = "twenty";
                    break;
                case "30": convert = "thirty";
                    break;
                case "40": convert = "forty";
                    break;
                case "50": convert = "fivty";
                    break;
                case "60": convert = "sixty";
                    break;
                case "70": convert = "seventy";
                    break;
                case "80": convert = "eighty";
                    break;
                case "90": convert = "ninety";
                    break;
            }

            return convert;
        }


        public static void Main(string[] args)
        {
            Console.Write("Write number in the range [0…999]: ");
            string number = Console.ReadLine();
            int length = number.Length;
            string result = "error";

            if (length == 1)
            {
                string pointer = char.ToString(number[0]);
                result = ContainerOfNumbers(pointer);
            }
            else if (length == 2)
            {
                string pointer = number[0] + "0";
                string firstDigit = ContainerOfNumbers(pointer);

                pointer = char.ToString(number[1]);
                string secondDigit = ContainerOfNumbers(pointer);

                result = firstDigit + secondDigit;
            }
            else if (length == 3)
            {
                string pointer = char.ToString(number[0]);
                string firstDigit = ContainerOfNumbers(pointer);

                pointer = number[1] + "0";
                string secondDigit = ContainerOfNumbers(pointer);

                pointer = char.ToString(number[2]);
                string thirdDigit = ContainerOfNumbers(pointer);

                result = firstDigit + "hundred and " + secondDigit + thirdDigit;
            }
            else
            {
                Console.WriteLine("error");
            }

            string ConvertFirstToUppercase = char.ToUpper(result[0]) + result.Substring(1);
            Console.WriteLine(ConvertFirstToUppercase);
        }
    }
}