How to Convert a numbers to words in asp.net with C#

Introduction
In this article explains about how to convert a numeric value to words.
For Example: Numeric: 500
 In Words: Five hundred Only

staticclass NumberToWord
{ 
  private static string[] _ones =
   {
     "zero",
     "one",
     "two",
     "three",
     "four",
     "five",
     "six",
     "seven",
     "eight",
     "nine"
   }; 
 private static string[] _teens =
  { 
     "ten",
     "eleven",
     "twelve",
     "thirteen",
     "fourteen",
     "fifteen",
     "sixteen",
     "seventeen",
     "eighteen",
     "nineteen"
  };
 private static string[] _tens =
  {
     "",
     "ten",
     "twenty",
     "thirty",
     "forty",
     "fifty",
     "sixty",
     "seventy",
     "eighty",
     "ninety"
  };
 private static string[] _thousands =
  {
     "",
     "thousand",
     "million",
     "billion",
     "trillion",
     "quadrillion"
  };

 public static string Convert(decimal value)
  { 
    string digits, temp;
    bool showThousands = false;
    bool allZeros = true;           
    StringBuilder builder = new StringBuilder();
    digits = ((long)value).ToString(); 
    for(int i = digits.Length-1; i >= 0; i--)
    {
      int ndigit = (int)(digits[i] - '0');
      int column = (digits.Length - (i + 1));
      switch (column % 3)
      { 
  case 0:   
       showThousands = true; 
       if (i == 0)
         {
           temp =String.Format("{0} ", _ones[ndigit]);
         }
       else if (digits[i - 1] == '1')
         {
           temp = String.Format("{0} ", _teens[ndigit]);
           i--;
         }
       else if (ndigit != 0)
        {
          temp = String.Format("{0} ", _ones[ndigit]);
        }
       else
        {
          temp = String.Empty;
          if (digits[i - 1] != '0' || (i > 1 && digits[i - 2] != '0'))
          showThousands = true;
          else
          showThousands = false;
        }
       if (showThousands)
       {
        if (column > 0)
        {
         temp = String.Format("{0}{1}{2}",
                temp,_thousands[column / 3], allZeros ? " " : " ");
        }
        allZeros = false;
       }
       builder.Insert(0, temp);
       break;

 case 1:
        if (ndigit > 0)
        {
         temp = String.Format("{0}{1}",_tens[ndigit],
         (digits[i + 1] != '0') ? "-" : " ");builder.Insert(0, temp);
       }
       break;
 
case 2:
      if (ndigit > 0)
        {
         temp = String.Format("{0} hundred ", _ones[ndigit]);
                    builder.Insert(0, temp);
       }
       break;
     }}
   builder.AppendFormat("only", (value - (long)value) * 100);
   return String.Format("{0}{1}",
   Char.ToUpper(builder[0]),
   builder.ToString(1, builder.Length - 1));
  }  
}

 
Add following code on Button_Click event

decimal number;
if (!string.IsNullOrEmpty(txtAmount.Text) 

&& decimal.TryParse(txtAmount.Text.Trim(), out number))
{
   lblAmountChar.Text = "(" + NumberToWord.Convert(number) + ")";
}