Imports System

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Imports Microsoft.VisualBasic

Public Module Module1

    Public Class TestClass

        Public Function GetFieldByBIN(sCardPAN As String, sDataTable As String) As String

            Dim iStart As Integer

            Dim iEnd As Integer

            Dim sCardMatch As String = String.Empty

            Dim iTestBinLength As Integer

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            For iTestBinLength = 10 To 6 Step -1

                sCardMatch = Mid(sCardPAN, 1, iTestBinLength) & " "

                iStart = InStr(1, sDataTable, sCardMatch, vbBinaryCompare)

                If iStart > 0 Then Exit For ' found it...move on

            Next

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            iStart = InStr(1, sDataTable, sCardMatch, vbTextCompare)

            If Not iStart = 0 Then

                iEnd = InStr(iStart, sDataTable, ",", vbTextCompare)

                If iEnd = 0 Then    ' if at the end of the type table

                    iEnd = Len(sDataTable) + 1

                End If

            Else

                GetFieldByBIN = ""

                Exit Function

            End If

            iStart = iStart + iTestBinLength + 1 ' bump over bin to get format name

            GetFieldByBIN = Mid(sDataTable, iStart, iEnd - iStart) ' convert type to format name

        End Function

    End Class

    Public Sub Main()   

        Dim testClass As TestClass = New TestClass

        Dim cardPrefix = testClass.GetFieldByBIN("1234561234561234", "123456 123457,12345612 123458")   

        Console.WriteLine("Card prefix = " + cardPrefix)

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        cardPrefix = testClass.GetFieldByBIN("1234561334561234", "123456 123457,12345612 123458")   

        Console.WriteLine("Card prefix = " + cardPrefix)

​

        cardPrefix = testClass.GetFieldByBIN("1234561234561234", "")    

        Console.WriteLine("Card prefix = " + cardPrefix)

    End Sub

End Module

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