C# Numbers to Words example

        public static string NumberToWords(this Decimal d)

        {

            if (d == 0)

            {

                return ("Zero Dollars and No Cents");

            }

            d = Math.Abs(d);

            string[] ones = { "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine" };

            string[] teens = { "Ten", "Eleven", "Twelve", "Thirteen", "Fourteen", "Fifteen", "Sixteen", "Seventeen", "Eighteen", "Nineteen" };

            string[] tens = { "Twenty", "Thirty", "Forty", "Fifty", "Sixty", "Seventy", "Eighty", "Ninety" };

            string[] magnitude = { "Hundred", "Thousand", "Million", "Billion", "Trillion", "Quadrillion", "WholeBunch" };

            byte Digit1, Digit2, Digit3, Digit2And3;

            int ndx;

            ArrayList wordSegments = new ArrayList();

            string wordAmount = string.Empty;

            string wordSegment = string.Empty;

            Int64 dollarAmount = Convert.ToInt64(Math.Floor(d));

            byte centsAmount = Convert.ToByte((System.Convert.ToDouble(d) - System.Convert.ToDouble(dollarAmount)) * 100);

            string segmentedNumber = d.ToString("###,###.00");

            string[] NumericSegments = segmentedNumber.Split(new string[] { ",", "." }, StringSplitOptions.RemoveEmptyEntries);

            for (ndx = 0; ndx < NumericSegments.Length; ndx++)

            {

                NumericSegments[ndx] = NumericSegments[ndx].PadLeft(3, Convert.ToChar("0"));

            }

            foreach (string NumericSegment in NumericSegments)

            {

                Digit1 = Convert.ToByte(Convert.ToString(NumericSegment[0]));

                Digit2 = Convert.ToByte(Convert.ToString(NumericSegment[1]));

                Digit3 = Convert.ToByte(Convert.ToString(NumericSegment[2]));

                Digit2And3 = Convert.ToByte(NumericSegment.Substring(1, 2));

                if (Digit1 > 0)  //in the hundreds

                {

                    wordSegment = ones[Digit1 - 1] + " Hundred";

                }

                if (Digit2And3 > 19) //over the teens

                {

                    wordSegment += (wordSegment.Length > 0 ? " and " : " ") + tens[Digit2 - 2];

                    if (Digit3 > 0) //has a lower decimal

                    {

                        wordSegment += "-" + ones[Digit3 - 1];

                    }

                }

                else

                {

                    if (Digit2And3 > 9) //teens

                    {

                        wordSegment += (wordSegment.Length > 0 ? " and " : " ") + teens[Digit3];

                    }

                    else

                    {

                        if (Digit3 > 0) //under teens

                        {

                            wordSegment += " " + ones[Digit3 - 1];

                        }

                    }

                }

                wordSegments.Add(wordSegment);

                wordSegment = string.Empty;

            }

            wordSegments.Reverse();

            for (ndx = 0; ndx < wordSegments.Count; ndx++)

            {

                string currentSegment = (string)wordSegments[ndx];

                switch (ndx)

                {

                    case 0:

                    wordAmount = (centsAmount == 0 ? " No Cents" : currentSegment + " Cent" + (centsAmount > 1 ? "s" : ""));

                    break;

                    case 1:

                    wordAmount = currentSegment + " Dollar" + (dollarAmount > 1 ? "s" : "") + " and" + wordAmount;

                    break;

                    default:

                    wordAmount = currentSegment + " " + magnitude[ndx - 1] + ", " + wordAmount;

                    break;

                }

            }

            wordAmount = wordAmount.Trim();

            string savedWordAmount = wordAmount;

            //wraps the string once

            try

            {

                const int maxLength = 70;

                if (wordAmount.Length > maxLength)

                {

                    string firstbit = wordAmount.Substring(0, maxLength);

                    int lastSpace = firstbit.LastIndexOf(" ");

                    wordAmount = wordAmount.Remove(lastSpace, 1);

                    wordAmount = wordAmount.Insert(lastSpace, Environment.NewLine);

                }

            }

            catch (Exception ex)

            {

                wordAmount = savedWordAmount;

            }

            return wordAmount;

        }