Module ModMain
Sub Main()
Do
Console.ForegroundColor = ConsoleColor.White
Console.Write("Barcode: ")
Console.ForegroundColor = ConsoleColor.Green
Dim Code As String = Console.ReadLine
If Code.Length = &HC Then
Console.CursorTop -= &H1
Console.CursorLeft = &H15
Console.ForegroundColor = ConsoleColor.Red
Console.WriteLine(CCC13_Checksum(Code))
Else
Console.WriteLine("Error! Enter the 12 first digits of your EAN13 code.")
End If
Loop
End Sub
Private Function CCC13_Checksum(ByVal Line As String) As Byte
Dim Factor As Int32 = &H3
Dim Sum As Int32 = &H0
For Index As Integer = (Line.Length - &H1) To &H0 Step -&H1
Sum = Sum + (CInt(Line.Substring(Index, &H1)) * Factor)
Factor = &H4 - Factor
Next
Return ((&H3E8 - Sum) Mod &HA)
End Function
End Module