'***************************************************************
' Name: Credit Card Checksum Checker
' Description:Checks to see if a Credit Card Number is valid by p
' erforming the LUHN-10 check on it.
' By: John Anderson
'
'
' Inputs:CCNum as String
'
' Returns:True if Valid, False if Invalid
'
'Assumes:None
'
'Side Effects:May cause skin irritation
'
'Warranty:
'Code provided by Planet Source Code(tm) (http://www.Planet-Sourc
' e-Code.com) 'as is', without warranties as to performance, fitnes
' s, merchantability,and any other warranty (whether expressed or i
' mplied).
'Terms of Agreement:
'By using this source code, you agree to the following terms...
' 1) You may use this source code in personal projects and may co
' mpile it into an .exe/.dll/.ocx and distribute it in binary forma
' t freely and with no charge.
' 2) You MAY NOT redistribute this source code (for example to a 
' web site) without written permission from the original author.Fai
' lure to do so is a violation of copyright laws.
' 3) You may link to this code from another website, provided it 
' is not wrapped in a frame.
' 4) The author of this code may have retained certain additional
' copyright rights.If so, this is indicated in the author's descrip
' tion.
'***************************************************************



Public Function IsValidCCNum(CCNum As String) As Boolean


Dim i As Integer
Dim total As Integer
Dim TempMultiplier As String


For i = Len(CCNum) To 2 Step -2
total = total + CInt(Mid$(CCNum, i, 1))
TempMultiplier = CStr((Mid$(CCNum, i - 1, 1)) * 2)
total = total + CInt(Left$(TempMultiplier, 1))
If Len(TempMultiplier) > 1 Then total = total +
CInt(Right$(TempMultiplier, 1))
Next


If Len(CCNum) Mod 2 = 1 Then total = total + CInt(Left$(CCNum, 1))


If total Mod 10 = 0 Then
IsValidCCNum = True
Else
IsValidCCNum = False
End If


End Function