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Function CheckCard(CCNumber As String) _
As Boolean
Dim Counter As Integer, TmpInt As Integer
Dim Answer As Integer
Counter = 1
TmpInt = 0
While Counter <= Len(CCNumber)
If IsEven(Len(CCNumber)) Then
TmpInt = Val(Mid$(CCNumber, Counter, 1))
If Not IsEven(Counter) Then
TmpInt = TmpInt * 2
If TmpInt > 9 Then TmpInt = TmpInt - 9
End If
Answer = Answer + TmpInt
'Debug.Print Counter, TmpInt, Answer
Counter = Counter + 1
Else
TmpInt = Val(Mid$(CCNumber, Counter, 1))
If IsEven(Counter) Then
TmpInt = TmpInt * 2
If TmpInt > 9 Then TmpInt = TmpInt - 9
End If
Answer = Answer + TmpInt
'Debug.Print Counter, TmpInt, Answer
Counter = Counter + 1
End If
Wend
Answer = Answer Mod 10
If Answer = 0 Then CheckCard = True
End Function
Private Sub cmdCheck_Click()
Msgbox CheckCard(txtNumber)
End Sub