C#: Printing Bank Check Amounts (Converting Numbers to Words)


I needed to add the ability to print checks from an application I was writing and a portion of that process included converting a number into its english text representation (ie $25.00 to Twenty Five Dollars). I thought that the .Net Framework would have some sort of conversion function built in but I could not find one so I went to the internet and found a pretty good one here. Firstly, I found a bug in the code when converting anything that was a multiple of 100,000; it wouldn’t include the ‘Thousand’ in the resulting string and thus converting 100,000 would result in ‘One Hundred’. I fixed that pretty quickly but it still wasn’t exactly what I needed as it didn’t handle decimal or floating point numbers. I wrote another method that utilized it but handeled decimal numbers.

        public static string NumberToCurrencyText(decimal number, MidpointRounding midpointRounding)
        {
            // Round the value just in case the decimal value is longer than two digits
            number = decimal.Round(number, 2, midpointRounding);

            string wordNumber = string.Empty;

            // Divide the number into the whole and fractional part strings
            string[] arrNumber = number.ToString().Split('.');

            // Get the whole number text
            long wholePart = long.Parse(arrNumber[0]);
            string strWholePart = NumberToText(wholePart);

            // For amounts of zero dollars show 'No Dollars...' instead of 'Zero Dollars...'
            wordNumber = (wholePart == 0 ? "No" : strWholePart) + (wholePart == 1 ? " Dollar and " : " Dollars and ");

            // If the array has more than one element then there is a fractional part otherwise there isn't
            // just add 'No Cents' to the end
            if (arrNumber.Length > 1)
            {
                // If the length of the fractional element is only 1, add a 0 so that the text returned isn't,
                // 'One', 'Two', etc but 'Ten', 'Twenty', etc.
                long fractionPart = long.Parse((arrNumber[1].Length == 1 ? arrNumber[1] + "0" : arrNumber[1]));
                string strFarctionPart = NumberToText(fractionPart);

                wordNumber += (fractionPart == 0 ? " No" : strFarctionPart) + (fractionPart == 1 ? " Cent" : " Cents");
            }
            else
                wordNumber += "No Cents";

            return wordNumber;           
        }


        public static string NumberToText(long number)
        {
            StringBuilder wordNumber = new StringBuilder();                       

            string[] powers = new string[] { "Thousand ", "Million ", "Billion " };
            string[] tens = new string[] { "Twenty", "Thirty", "Forty", "Fifty", "Sixty", "Seventy", "Eighty", "Ninety" };
            string[] ones = new string[] { "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine", "Ten", 
                                           "Eleven", "Twelve", "Thirteen", "Fourteen", "Fifteen", "Sixteen", "Seventeen", "Eighteen", "Nineteen" };

            if (number == 0) { return "Zero"; }
            if (number < 0) 
            { 
                wordNumber.Append("Negative ");
                number = -number;
            }

            long[] groupedNumber = new long[] { 0, 0, 0, 0 };
            int groupIndex = 0;

            while (number > 0)
            {
                groupedNumber[groupIndex++] = number % 1000;
                number /= 1000;
            }

            for (int i = 3; i >= 0; i--)
            {
                long group = groupedNumber[i];

                if (group >= 100)
                {
                    wordNumber.Append(ones[group / 100 - 1] + " Hundred ");
                    group %= 100;

                    if (group == 0 && i > 0)
                        wordNumber.Append(powers[i - 1]);
                }

                if (group >= 20)
                {
                    if ((group % 10) != 0)
                        wordNumber.Append(tens[group / 10 - 2] + " " + ones[group % 10 - 1] + " ");
                    else
                        wordNumber.Append(tens[group / 10 - 2] + " ");                    
                }
                else if (group > 0)
                    wordNumber.Append(ones[group - 1] + " ");

                if (group != 0 && i > 0)
                    wordNumber.Append(powers[i - 1]);
            }

            return wordNumber.ToString().Trim();
        }
    }

I have tested this quite a bit but I make no guarantees.

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