05.ConditionalStatementsHomework/11.NumberAsWords

//Problem 11.* Number as Words
//Write a program that converts a number in the range [0…999] to words, corresponding to the English pronunciation.

using System;

class NumberAsWords
{
    static void Main()
    {
        string[] digits = {"zero" ,"one", "two", "three", "four", "five", "six", "seven", "eight","nine" };
        string[] special = {"ten", "eleven", "twelve", "thirdtheen", "fourthen", "fiftheen", "sixtheen", "seventheen", "eightheen", "ninetheen" };
        string[] dec = {"", "", "twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninety"};
        int input = 0;
        Console.WriteLine("Please enter a number in the range [0, 999]");
        bool isValid = int.TryParse(Console.ReadLine(), out input);
        if (isValid && input >= 0 && input < 1000)
        {
            int digit = input % 10;
            int tens = (input / 10) % 10;
            int hundred = (input / 100) % 10;
            if (hundred != 0)
            {
                Console.Write("{0} hundred ", digits[hundred]);
                if (tens != 0 && tens != 1 && input >= 20)
                {
                    Console.Write("and {0} ", dec[tens]);
                    if (digit != 0)
                    {
                        Console.Write("{0} ", digits[digit]);
                    }
                }
                else if (tens == 1)
                {
                    Console.Write("and {0}", special[digit]);
                }
                else
                {
                    if (digit != 0)
                    {
                        Console.Write("and {0} ", digits[digit]);
                    }
                }
            }
            else
            {
                // hundreds = 0
                if (tens != 0 && tens != 1 && input >= 20)
                {
                    Console.Write("{0} ", dec[tens]);
                    Console.Write("{0} ", digits[digit]);
                }
                else if (tens == 1)
                {
                    Console.Write("{0}", special[digit]);
                }
                else
                {
                    Console.Write("{0} ", digits[digit]);
                }
            }
            Console.WriteLine();
        }
        else
        {
            Console.WriteLine("Out of range.Please, try again!");
        }
    }
}