Code 39 barcodes with check digits in Excel
Azalea_Code_39_checkdigit
Copyright 2009 Azalea Software, Inc. All rights reserved. www.azalea.com


The macro in this spreadsheet creates Code 39 (Code 3 of 9) barcodes with the optional mod 43 check digit. Please note that this check digit is rarely used with Code 39 barcodes.

Because this spreadsheet is built around a macro, you *must* enable macros for this spreadsheet to work! The .xls file is for Excel 2003 and the .xlsm is for Excel 2007. An alternative is to use a User Defined Function as an .xla (Excel 2003) or .xlam (Excel 2007).

Press ALT-F11 to view the macro in the Visual Basic Editor.

To add the macro to your own spreadsheet:
  Tools/Macro/Visual Basic Editor
  Insert/Module
  Paste in the macro code
  Close the Visual Basic Editor

When you return to your spreadsheet, a new User Defined function is available: Azalea_Code_39_checkdigit

C39Tools prints Code 39 barcodes. Available for Windows, OS X, Linux/UNIX, et al. Free sample code and free tech support. Buy online and download immediately.

www.azalea.com/Code-39


Function Azalea_Code_39_checkdigit(ByVal Code39 As String) As String
' C39Tools 25mar09 jwhiting
' Copyright 2009 Azalea Software, Inc. All rights reserved. www.azalea.com

' Creating a Code 39 barcode with the optional mod 43 check digit in Excel
' Your input, Code39, is a string to be encoded as a Code 39 symbol that includes the mod 43 check digit.
' yourData must be the Code 39 character set. Input error checking is your responsibility.
' The standard Code 39 character set is: A-Z (upppercase), 0-9, $ % + - . / and the space character.

  Dim i As Integer                   ' our loop counter
  Dim subtotal As Integer            ' the check digit subtotal
  Dim temp As String                 ' a temporary placeholder
  
  temp = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ-. $/+%"

  ' calculate the mod 43 check digit
  For i = 1 To Len(Code39)
    subtotal = InStr(temp, Mid(Code39, i, 1)) - 1 + subtotal
  Next i

  ' concatenate the original string, Code39, and the check digit character
  Azalea_Code_39_checkdigit = "*" + Code39 & Mid(temp, (subtotal Mod 43 + 1), 1) + "*"

  ' Excel: B1=Azalea_Code_39_checkdigit(A1)
  ' Or put another way, yourContainer.text=Azalea_Code_39_checkdigit(yourInputString)
  
End Function