Numbers as words

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Problem_11.Number_as_Words
{
    class NumberAsWords
    {
        static void Main()
        {
            Console.WriteLine("Enter integer number between 0 and 999.");
            string number = Console.ReadLine();
            int non;
            string[] numbers = new string[number.Length];
            string ones = null;
            string tens = null;
            string hundreds = null;
            string numberSentence = null;

            while (!int.TryParse(number,out non) || non < 0 || non > 999)
            {
                if (!int.TryParse(number, out non))
                {
                    Console.WriteLine("Invalid data");
                }
                else
                {
                    Console.WriteLine("Number is out of range.");
                }
                number = Console.ReadLine();
            }

            for (int i = 0; i < number.Length; i++)
            {
                if (number.Length == 3 && i == 0)
                {
                    switch (number[i])
                    {
                        case '0':
                            hundreds = null;
                            break;
                        case '1':
                            hundreds = "one hundred";
                            break;
                        case '2':
                            hundreds = "two hundred";
                            break;
                        case '3':
                            hundreds = "thiree hundred";
                            break;
                        case '4':
                            hundreds = "four hundred";
                            break;
                        case '5':
                            hundreds = "five hundred";
                            break;
                        case '6':
                            hundreds = "six hundred";
                            break;
                        case '7':
                            hundreds = "seven hundred";
                            break;
                        case '8':
                            hundreds = "eight hundred";
                            break;
                        case '9':
                            hundreds = "nine hundred";
                            break;
                    }
                }
                if ((number.Length == 3 && i == 1) || (number.Length == 2 && i == 0))
                {
                    switch (number[i])
                    {
                        case '0':
                            tens = null;
                            break;
                        case '1':
                            tens = "teen";
                            break;
                        case '2':
                            tens = "twenty";
                            break;
                        case '3':
                            tens = "thirty";
                            break;
                        case '4':
                            tens = "forty";
                            break;
                        case '5':
                            tens = "fifty";
                            break;
                        case '6':
                            tens = "sixty";
                            break;
                        case '7':
                            tens = "seventy";
                            break;
                        case '8':
                            tens = "eighty";
                            break;
                        case '9':
                            tens = "ninety";
                            break;
                    }
                }
                if (tens == "teen" && ((number.Length == 3 && i == 2) || (number.Length == 2 && i == 1)))
                {
                    switch (number[i])
                    {
                        case '0':
                            ones = "ten";
                            break;
                        case '1':
                            ones = "eleven";
                            break;
                        case '2':
                            ones = "twelve";
                            break;
                        case '3':
                            ones = "thirteen";
                            break;
                        case '4':
                            ones = "fourteen";
                            break;
                        case '5':
                            ones = "fifteen";
                            break;
                        case '6':
                            ones = "sixteen";
                            break;
                        case '7':
                            ones = "seventeen";
                            break;
                        case '8':
                            ones = "eighteen";
                            break;
                        case '9':
                            ones = "nineteen";
                            break;
                    }
                }
                else if ((number.Length == 3 && i == 2) || (number.Length == 2 && i == 1) || number.Length == 1)
                {
                    switch (number[i])
                    {
                        case '0':
                            if (number.Length == 1)
                            {
                                ones = "Zero";
                            }
                            else
                            {
                                ones = null;
                            }
                            break;
                        case '1':
                            ones = "one";
                            break;
                        case '2':
                            ones = "two";
                            break;
                        case '3':
                            ones = "thiree";
                            break;
                        case '4':
                            ones = "four";
                            break;
                        case '5':
                            ones = "five";
                            break;
                        case '6':
                            ones = "six";
                            break;
                        case '7':
                            ones = "seven";
                            break;
                        case '8':
                            ones = "eight";
                            break;
                        case '9':
                            ones = "nine";
                            break;
                    }
                }
            }

            switch (number.Length)
            {
                case 1:
                    numberSentence = ones;
                    break;
                case 2:
                    if (tens == "teen")
                    {
                        numberSentence = ones;
                    }
                    else if (ones != null)
                    {
                        numberSentence = tens + " " + ones;
                    }
                    else
                    {
                        numberSentence = tens;
                    }
                    break;
                case 3:
                    if (tens == null && ones == null)
                    {
                        numberSentence = hundreds;
                    }
                    else if (tens == "teen")
                    {
                        numberSentence = hundreds + " and " + ones;
                    }
                    else if (ones != null)
                    {
                        numberSentence = hundreds + " and " + tens + " " + ones;
                    }
                    else
                    {
                        numberSentence = hundreds + " and " + tens;
                    }
                    break;
            }

            Console.WriteLine(numberSentence);
        }
    }
}