Convert Numbers to Words Neatly

#Region "REMARKS (PLEASE DO NOT REMOVE)"

'-----REMARKS-------------------------------------------------------------------------------------------------------
'-------------------------------------------------------------------------------------------------------------------
'Created by: Normz Antonino
'Dated November 07, 2012
'Email: normzant@yahoo.com
'This program converts numbers into words. I created a recursive function to minimize lines of codes and make it neat.
'I added comments for clear idea on the program flow.
'You can remove the comments I put in the function but please, as a gratitude, don't remove these remarks

'NOTE: DO NOT USE any type-casting when putting big numbers such as Trillion, Quadrillion and Quintillion into the function like CAST, CINT, VAL, especially CSNG and CDBL
'for they will tamper the result (See my comments inside the function for reason)
'If you intend to put big numbers, put the values as string type, not double. The function has a trapper for alpha anyway. 
'As clarification on the matter to differentiate the result of the function, use this example: 
'Under the btnConvert_Click, switch between the line of codes below and use any of these values as input: 42326432465566423 or 424212332333412.66 or 282352345233221.66
'               MsgBox(AmountInWords(txtAmount.Text)) 'Correctly displayed
'               MsgBox(AmountInWords(Val(txtAmount.Text))) 'or use MsgBox(AmountInWords(CDbl(txtAmount.Text))) 'Incorrect display or error encountered

'You see? Just for big numbers anyway. No worries for billion and below

'Sample Input Value Used in the Function: 9223372036854775807.75 (9223372036854775807 is the maximum value for LONG datatype) 
'I added the decimal value .75 to test the functionality for decimal values
'-------------------------------------------------------------------------------------------------------------------
'-------------------------------------------------------------------------------------------------------------------

#End Region

Public Class frmNumbersToWords

#Region "Buttons"

    Private Sub btnConvert_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnConvert.Click
        'MsgBox(AmountInWords(txtAmount.Text))
        lblResult.Text = AmountInWords(txtAmount.Text)
    End Sub

    Private Sub btnClose_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClose.Click
        End
    End Sub

#End Region

#Region "Convert To Words Function"

    Public Function AmountInWords(ByVal nAmount As String, Optional ByVal wAmount As String = vbNullString, Optional ByVal nSet As Object = Nothing) As String
        'Let's make sure entered value is numeric
        If Not IsNumeric(nAmount) Then Return "Please enter numeric values only."

        'I used this kind of approach using String instead of Double as datatype then I applied string manipulation
        'and remove the decimal value then store it in tempDecValue and re-attach it to nAmount upon entering the recursion
        'The reason is that I tried using the Double datatype but when it comes to quadrillion values and with decimal values
        'I noticed that the ones and tens values changed, or some errors encountered. I couldn't figure it out until I came up with this concept.

        'tempDecValue gets the decimal value from the original value nAmount 
        'tempDecValue is added to the nAmount every time it enters the recursion
        Dim tempDecValue As String = String.Empty : If InStr(nAmount, ".") Then tempDecValue = nAmount.Substring(nAmount.IndexOf("."))

        'Removing the decimal value from nAmount
        nAmount = Replace(nAmount, tempDecValue, String.Empty)

        Try
            'Assigning the nAmount to intAmount having the LONG datatype
            Dim intAmount As Long = nAmount

            'Let's trap the values entered into the recursion; if greater than 0 then let's evaluate the numbers in set, otherwise, 
            '(1) all numbers have already been evaluated and return the designated word values (for entered whole numbers); or
            '(2) evaluate last set, which is the decimal value
            'either which proceed to else statement and/or return the result
            If intAmount > 0 Then
                'Let's segregate the entered values into 3-digit sets of numbers and count it then store in the nSet
                'For example: 9223372036854775807 has 7 sets; start from right to left (807, 775, 854, 036...), until the last set which is 9 
                nSet = IIf((intAmount.ToString.Trim.Length / 3) > (CLng(intAmount.ToString.Trim.Length / 3)), CLng(intAmount.ToString.Trim.Length / 3) + 1, CLng(intAmount.ToString.Trim.Length / 3))

                'eAmount gets each 3-digit set entered into the recursion
                'Though I said sets start from right to left, we start evaluating each set from left to right of the entered values.
                'For example: 9223372036854775807 (actual: 9,223,372,036,854,775,807), 9 (1st set to be evaluated), 223 (next set), 372 (next set),... and so on
                'and so forth until all are evaluated, including the decimal values, in case there exists
                'NOTE: 9 is in Quintillion range, 223 is in Quadrillion, 372 in Trillion, and so on and so forth
                Dim eAmount As Long = Microsoft.VisualBasic.Left(intAmount.ToString.Trim, (intAmount.ToString.Trim.Length - ((nSet - 1) * 3)))

                'Multiplier gets the 10 to the power of the nSet
                'This is needed to remove the evaluated set from the original values
                'For example: 1st set is 9 (the 1st value of eAmount) and there are 7 sets so:
                '10 ^ (((7 - 1) * 3)) is 1000000000000000000
                '9 multiplied by 1000000000000000000 is 9000000000000000000
                'remove 9000000000000000000 from 9223372036854775807 which results in 223372036854775807, the next value of nAmount within which the decimal value .75 shall be attached
                'the flow goes on and on until nAmount reaches zero, or the decimal value
                'so multiplier has a vital function as we go on and we shall see later
                Dim multiplier As Long = 10 ^ (((nSet - 1) * 3))

                'These are the worded values
                Dim Ones() As String = {"", "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine"}
                Dim Teens() As String = {"", "Eleven", "Twelve", "Thirteen", "Fourteen", "Fifteen", "Sixteen", "Seventeen", "Eighteen", "Nineteen"}
                Dim Tens() As String = {"", "Ten", "Twenty", "Thirty", "Forty", "Fifty", "Sixty", "Seventy", "Eighty", "Ninety"}
                Dim HMBT() As String = {"", "", "Thousand", "Million", "Billion", "Trillion", "Quadrillion", "Quintillion"}

                'Let's reuse the intAmount object
                intAmount = eAmount

                'Remember, we have a 3-digit number in each set
                'from left to right is hundreds, tens, and ones
                'For example 9 is the ones in the first set for evaluation; the next set is 223 (1st 2 is hundreds, next 2 is tens, and 3 is ones)
                'These statements segregate the numbers in the set
                Dim nHundred As Integer = intAmount \ 100 : intAmount = intAmount Mod 100
                Dim nTen As Integer = intAmount \ 10 : intAmount = intAmount Mod 10
                Dim nOne As Integer = intAmount \ 1

                'After the segregation, we now have to evaluate the retrieved numbers and put the corresponding words for each number                
                If nHundred > 0 Then wAmount = wAmount & Ones(nHundred) & " Hundred " 'This is for hundreds                
                If nTen > 0 Then 'This is for tens and teens
                    'In case of teens, like 11 to 19, it will be trapped in here and proceed to the designated word                    
                    If nTen = 1 And nOne > 0 Then 'This is for teens (number ten plus ones succeeding it) Example:
                        wAmount = wAmount & Teens(nOne) & " " '11 is Eleven, 12 is Twelve, 15 is Fifteen, 17 is Seventeen, and so on
                    Else 'This is for tens, 10 to 90
                        wAmount = wAmount & Tens(nTen) & IIf(nOne > 0, "-", " ") 'If there is ones succeeding it, put a dash before the ones, example: Twenty-, Thirty-, Forty-, etc.
                        If nOne > 0 Then wAmount = wAmount & Ones(nOne) & " " 'This is for ones (1-9) with the tens (20-90) preceeding it. Example: 21 is Twenty-One, 34 is Thirty-Four, 48 is Forty-Eight
                    End If
                Else 'This is for ones, 1 to 9
                    If nOne > 0 Then wAmount = wAmount & Ones(nOne) & " "
                End If
                'Let's put in here the ranges (1st set(number 9) is Quintillion, next(number 223) is Quadrillion, next(372) is Trillion, ...so on and so forth)
                wAmount = wAmount & HMBT(nSet) & " "
                'Proceed to next set to evaluate by entering the same function we are in (recursion)
                wAmount = AmountInWords(CStr(CLng(nAmount) - (eAmount * multiplier)).Trim & tempDecValue, wAmount, nSet - 1)
            Else 'When nAmount reaches 0, we proceed to this statement
                'If there is no decimal value then proceed to display the result
                'But if there is a decimal value then let's evaluate each number of the decimal value
                'First we re-attach the decimal value to its original value, the nAmount
                If Val(nAmount) = 0 Then nAmount = nAmount & tempDecValue : tempDecValue = String.Empty
                'Now, if we have decimal value, let's convert it into whole numbers (not rounding it off, but actually converting to whole numbers), 
                'put it into the recursion for the last time, evaluate it, give the corresponding words and then finally, display the result
                If (Math.Round(Val(nAmount), 2) * 100) > 0 Then wAmount = Trim(AmountInWords(CStr(Math.Round(Val(nAmount), 2) * 100), wAmount.Trim & " Pesos And ", 1)) & " Cents"
            End If
        Catch ex As Exception
            'Should there be any error encountered, this will handle it.
            MessageBox.Show("Error Encountered: " & ex.Message, "Convert Numbers To Words", MessageBoxButtons.OK, MessageBoxIcon.Error)
            Return "!#ERROR_ENCOUNTERED"
        End Try

        'Trap null values
        If IsNothing(wAmount) = True Then wAmount = String.Empty Else wAmount = IIf(InStr(wAmount.Trim.ToLower, "pesos"), wAmount.Trim, wAmount.Trim & " Pesos")

        'Display the result
        Return wAmount
    End Function

#End Region

End Class