ValidateCard , , IBM 1960 . , . . , , . , , .
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ValidateCard. , ( ):
1 Function ValidateCard(CardNumber As String)
' ( )
2 Dim SumOfDigits
3 SumOfDigits = 0
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' (1)
4 Dim OddNumbered
5 OddNumbered = True
2 , . .
6 Dim i
7 For i = Len(CardNumber) To 1 Step -1
8 Dim CurrentNumber
9 CurrentNumber = Mid(CardNumber, i, 1)
10 If OddNumbered = False Then
'
11 CurrentNumber = CurrentNumber * 2
12 If CurrentNumber >= 10 Then '
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' ,
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13 Dim NumText As String
14 NumText = CurrentNumber
15 CurrentNumber = Val(Left(NumText, 1)) +
16 Val(Right(NumText, 1))
17 End If
18 End If
'
19 " SumOfDigits = SumOfDigits + CurrentNumber
.
' True False
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' False True
20 OddNumbered = Not OddNumbered
21 Next
' 10,
22 If SumOfDigits Mod 10 = 0 Then
23 ValidateCard = True
24 Else
25 ValidateCard = False
26 End If
27 End Function
.
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, ValidateCard, .
, , CardNumber:
Private Sub CardNumber_BeforeUpdate(Cancel As Integer)
If ValidateCard(CardNuraber) Then
MsgBox "Your card is valid," Else.
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MsgBox "Your card is invalid. " & _
"Did you forget a number, or are you trying to cheat us?" Cancel = True
End If
End Sub
CardNumber, . 17.3.
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. 17.3. Validate Card AddCreditCard ( ) Boutique Fudge. CardNumber, ,
