' This function checks to see if a file is open or not. If the file is

  ' already open, it returns True. If the file is not open, it returns

  ' False. Otherwise, a run-time error will occur because there is

  ' some other problem accessing the file.

  Function IsFileOpen(filename As String)

      Dim filenum As Integer, errnum As Integer

      On Error Resume Next   ' Turn error checking off.

      filenum = FreeFile()   ' Get a free file number.

      ' Attempt to open the file and lock it.

      Open filename For Input Lock Read As #filenum

      Close filenum          ' Close the file.

      errnum = Err           ' Save the error number that occurred.

      On Error GoTo 0        ' Turn error checking back on.

      ' Check to see which error occurred.

      Select Case errnum

          ' No error occurred.

          ' File is NOT already open by another user.

          Case 0

              IsFileOpen = False

          ' Error number for "Permission Denied."

          ' File is already opened by another user.

          Case 70

              IsFileOpen = True

          ' Another error occurred.

          Case Else

              Error errnum

      End Select

  End Function