Imports System
Module NumberToWords
'
' Convert numbers to English words in VB.NET
' ------------------------------------------
' Supports numbers from 0 to 999,999,999,999,999.
'
' Strategy:
' - Break the number into named groups: trillions, billions, millions,
' thousands, hundreds.
' - Convert each 0–999 group using a helper method.
' - Append group names ("trillion", "billion", etc.) when needed.
' - Build the final string with proper spacing.
'
Private ReadOnly Ones() As String = {
"zero", "one", "two", "three", "four",
"five", "six", "seven", "eight", "nine",
"ten", "eleven", "twelve", "thirteen", "fourteen",
"fifteen", "sixteen", "seventeen", "eighteen", "nineteen"
}
Private ReadOnly TensWords() As String = {
"", "", "twenty", "thirty", "forty",
"fifty", "sixty", "seventy", "eighty", "ninety"
}
'
' appendWord:
' Adds a word to the output with proper spacing.
'
Private Sub AppendWord(ByRef outStr As String, word As String)
If word <> "" Then
If outStr <> "" Then outStr &= " "
outStr &= word
End If
End Sub
'
' convertHundreds:
' Converts numbers from 0 to 999 into words.
'
Private Sub ConvertHundreds(n As Long, ByRef outStr As String)
If n = 0 Then Exit Sub
If n >= 100 Then
AppendWord(outStr, Ones(n \ 100))
AppendWord(outStr, "hundred")
n = n Mod 100
If n > 0 Then AppendWord(outStr, "and")
End If
If n >= 20 Then
AppendWord(outStr, TensWords(n \ 10))
If (n Mod 10) > 0 Then AppendWord(outStr, Ones(n Mod 10))
ElseIf n > 0 Then
AppendWord(outStr, Ones(n))
End If
End Sub
'
' numberToWords:
' Converts any number from 0 to 999,999,999,999,999 into English words.
'
Public Function NumberToWords(num As Long) As String
If num = 0 Then Return "zero"
Dim result As String = ""
Dim trillions As Long = num \ 1000000000000L
Dim billions As Long = (num \ 1000000000L) Mod 1000
Dim millions As Long = (num \ 1000000L) Mod 1000
Dim thousands As Long = (num \ 1000L) Mod 1000
Dim hundreds As Long = num Mod 1000
If trillions > 0 Then
ConvertHundreds(trillions, result)
AppendWord(result, "trillion")
End If
If billions > 0 Then
ConvertHundreds(billions, result)
AppendWord(result, "billion")
End If
If millions > 0 Then
ConvertHundreds(millions, result)
AppendWord(result, "million")
End If
If thousands > 0 Then
ConvertHundreds(thousands, result)
AppendWord(result, "thousand")
End If
If hundreds > 0 Then
ConvertHundreds(hundreds, result)
End If
Return result
End Function
'
' Main:
' Demonstrates usage with multiple test numbers.
'
Sub Main()
Dim tests() As Long = {
1234,
12345,
123456,
1234567,
123456789,
12345678901L,
1234567890123L,
999999999999999L
}
For Each n In tests
Console.WriteLine($"{n} -> {NumberToWords(n)}")
Next
End Sub
End Module
'
' run:
'
' 1234 -> one thousand two hundred and thirty four
' 12345 -> twelve thousand three hundred and forty five
' 123456 -> one hundred and twenty three thousand four hundred and fifty six
' 1234567 -> one million two hundred and thirty four thousand five hundred and sixty seven
' 123456789 -> one hundred and twenty three million four hundred and fifty six thousand seven hundred and eighty nine
' 12345678901 -> twelve billion three hundred and forty five million six hundred and seventy eight thousand nine hundred and one
' 1234567890123 -> one trillion two hundred and thirty four billion five hundred and sixty seven million eight hundred and ninety thousand one hundred and twenty three
' 999999999999999 -> nine hundred and ninety nine trillion nine hundred and ninety nine billion nine hundred and ninety nine million nine hundred and ninety nine thousand nine hundred and ninety nine
'
