Credit Card Checksum Checker
Checks to see if a Credit Card Number is valid by performing the LUHN-10 check on it.
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Source Code
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
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