| Проверить номер кредитной карточки |
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Воспользуйтесь алгоритмом Luhn: Function ValidateLuhn(ByVal Expression As String) As Boolean Dim ChkSum As Integer = 0, DblFlag As Boolean = (Expression.Length Mod 2 = 0) Dim OneChar As Char, OneCharValue As Integer For Each OneChar In Expression OneCharValue = Integer.Parse(OneChar) If DblFlag Then OneCharValue *= 2 If OneCharValue > 9 Then OneCharValue -= 9 End If End If ChkSum += OneCharValue DblFlag = Not DblFlag Next Return (ChkSum Mod 10 = 0) End Function |