How to Convert Number to Words using Recursion in ASP.NET (c#.net)

The purpose of this article is to make beginners to understand practical use of recursion in ASP.NET (c#.net). I have taken a practical scenario which occurs widely in most of the applications. Hence I have come up with code for converting a number into Indian Rupees.

Here is a function “ConvertToWords” recursively called since same notation applies for digits in Thousands, Lakhs and Crores place in number once number crosses 999.  

using System;

namespace NumberConvertor.Models

{

    public class NumberConverter

    {

        public static string ConvertToWords(double num,bool appendCurrency=true)

        {

            string[] tens = new string[] { "Ten", "Twenty", "Thirty", "Fourty", "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" };

            string result = "";

            //Finding Number of Crores in a given number

            int noOfCrores = ((int)num) / 10000000;

            if (noOfCrores > 0) result += ones[noOfCrores] +" Crore ";

            num-= 10000000 * noOfCrores;

            //Finding Number of lakhs in a given number

            int noOfLakhs = ((int)num) / 100000;

            if (noOfLakhs > 0) result += ConvertToWords(noOfLakhs,false) + " Lakh ";

            num -= noOfLakhs * 100000;

            //Finding Number of thousands in a given number

            int noOfThousands=((int)num)/1000;

            if (noOfThousands > 0) result += ConvertToWords(noOfThousands,false) + " Thounsand ";

            num -= noOfThousands * 1000;

            //Finding Number of hundreds in a given number

            int noOfHundreds = (int)num / 100;

            if (noOfHundreds > 0) result += ones[noOfHundreds - 1] + " Hundred ";

            num -= noOfHundreds * 100;

            if (num < 20)

                result += ones[(int)num - 1];

            else

                result += tens[((int)num / 10) - 1] + " "+ones[(int)num % 10 - 1];

            if (appendCurrency) result += " Rupees";

          

            //extract digits after decimal point

            num = (int)(Math.Round((num - (int)num) * 100));

           

           

            if (num > 0)

            {

                result +=" "+ ConvertToWords(num,false);

                if (appendCurrency) result += " Paise";

            }

            return result;

        }

}

}