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  1. #1

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    Resolved [RESOLVED] how to calculate EAN8 barcode checksum

    hello,
    in my app the user scans a barcode (EAN8) and i need my app to verify that barcode is correct,that is to check the checksum.

    i found online just the algorithm for the EAN13 but no EAN8.Someone worked with this one before?

    thanks

  2. #2
    .NUT jmcilhinney's Avatar
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    Re: how to calculate EAN8 barcode checksum

    This is not a VB.NET question. If you have the algorithm and you need help to implement it in VB.NET, THAT is a suitable question for this forum.
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  3. #3

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    Re: how to calculate EAN8 barcode checksum

    mmmm, yes , you're right, i think i was searching someone who worked with both vb.net and barcodes.
    my best regards.

  4. #4
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    Re: [RESOLVED] how to calculate EAN8 barcode checksum

    Code:
        Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
            MessageBox.Show(EAN8_Checksum("5512345"))
        End Sub
    
        Private Function EAN8_Checksum(ByVal EAN8_Barcode As String) As String
            'http://www.barcodeisland.com/ean8.phtml
    
            Dim ChecksumCalculation As Integer = 0
    
            Dim Position As Int32 = 1
            For i As Integer = EAN8_Barcode.Length - 1 To 0 Step -1
                If Position Mod 2 = 1 Then
                    'odd position
                    ChecksumCalculation += Convert.ToInt32(EAN8_Barcode.Substring(i, 1)) * 3
                Else
                    'even position
                    ChecksumCalculation += Convert.ToInt32(EAN8_Barcode.Substring(i, 1)) * 1
                End If
                Position += 1
            Next
    
            Dim Checksum As Integer = 10 - (ChecksumCalculation Mod 10)
    
            Return Convert.ToString(Checksum)
        End Function

  5. #5

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    Re: [RESOLVED] how to calculate EAN8 barcode checksum

    thank you,the URL you inserted in you're code really help me alot.

  6. #6
    Powered By Medtronic dbasnett's Avatar
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    Re: [RESOLVED] how to calculate EAN8 barcode checksum

    Wish I had paid attention to the dates... This does 8 and 13

    @MattP - got me

    Code:
        Private Function EAN_Checksum(ByVal EAN_Barcode As String, _
                                      Optional eanType As Integer = 8) As String
            Dim oddW As Integer 'odd weighting
            Dim evenW As Integer 'even weighting
            Dim isOdd As Boolean
    
            If eanType = 8 Then 'EAN8
                If EAN_Barcode.Length <> 7 Then
                    'error code needed
                    Throw New Exception
                End If
                oddW = 3
                evenW = 1
                isOdd = True
            ElseIf eanType = 13 Then 'EAN13
                If EAN_Barcode.Length <> 12 Then
                    'error code needed
                    Throw New Exception
                End If
                oddW = 1
                evenW = 3
                isOdd = False
            Else
                'error code needed
                Throw New Exception
            End If
            Dim Checksum As Integer
            'make sure the barcode is numeric
            If Long.TryParse(EAN_Barcode, Nothing) Then
                For Each c As String In EAN_Barcode.Reverse
                    If isOdd Then
                        'odd position
                        Checksum += Integer.Parse(c) * oddW
                    Else
                        'even position
                        Checksum += Integer.Parse(c) * evenW
                    End If
                    isOdd = Not isOdd
                Next
                Checksum = 10 - (Checksum Mod 10)
            Else
                'error code needed
                Throw New Exception
            End If
            Return Checksum.ToString
        End Function
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