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Credit Card Checksum Checker

Submitted on: 1/1/2015 3:02:00 PM
By: John Anderson (from psc cd)  
Level: Not Given
User Rating: By 106 Users
Compatibility: VB 3.0, VB 4.0 (16-bit), VB 4.0 (32-bit), VB 5.0, VB 6.0
Views: 1775
     Checks to see if a Credit Card Number is valid by performing the LUHN-10 check on it.
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' Name: Credit Card Checksum Checker
' Description:Checks to see if a Credit Card Number is valid by performing the LUHN-10 check on it.
' By: John Anderson (from psc cd)
' Inputs:CCNum as String
' Returns:True if Valid, False if Invalid
' Side Effects:May cause skin irritation

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))
If Len(CCNum) Mod 2 = 1 Then total = total + CInt(Left$(CCNum, 1))
If total Mod 10 = 0 Then
IsValidCCNum = True
IsValidCCNum = False
End If
End Function

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