Reading a .CSV File in VB6

The CSV file specs I followed can be read into / written from MS-Excel

Public Function ParseLineCSVExcel(ByRef strLine As String) As String

   'strLine will be altered witin this procedure and sent back.......

   'Excel's formula SEEMS to be when there are quotes & comma all mixed up is that
   ' an ODD number of quotes before a comma means that the comma IS DATA
   '     EVEN --------------------------------------------------------------------------- A DELIMETER
   '     ODD => open, IT IS DATA
   '     EVEN => closed, valid delimeter

Const ASCIISPACE As Long = 32                                                     '( )
Const ASCIIQUOTE As Long = 34                                                    '(")
Const ASCIICOMMA As Long = 44                                                 '(,)

Dim iStrlen As Integer
Dim bOpen As Boolean                                                               'If in open mode, then delimeters are actual data
Dim strBuild As String
Dim chChar As String * 1

iStrlen = Len(strLine)
If iStrlen = 0 Then                'nothing to do, but do not raise an error
   ParseLineCSVExcel = ""                     'pass an empty string back
   Exit Function
End If

'Brought this in from orig parse csv
If iStrlen = 1 And (Asc(strLine) = 34 Or Asc(strLine) = 44) Then
   strLine = ""
   ParseLineCSVExcel = ""
   Exit Function
End If

'Most bogus calls were terminated above, so now it's time to work!

strBuild = ""                                                                                          'Empty the output build variab;e
bOpen = False          'Treat 0 as an EVEN number of quotes

chChar = Left$(strLine, 1)
Do While iStrlen > 0
   If Asc(chChar) = ASCIIQUOTE Then
      If iStrlen = 1 Then                  'Assume it's the end of the data line
         ParseLineCSVExcel = strBuild 'loose the last quote
         Exit Function
      End If                                                                                       'Anything below this is essentally an "ELSE" clause
      bOpen = Not bOpen               'Toggle the flag
   End If

   If (Asc(chChar) = ASCIICOMMA) And (Not bOpen) Then 'Data closed, it's a delimeter
      strLine = Mid$(strLine, 2)                'Dump the delimeting comma
      If Len(strBuild) > 0 Then
         If Asc(Right$(strBuild, 1)) = ASCIIQUOTE Then
            strBuild = Left$(strBuild, (Len(strBuild) - 1))    'Return the built string *WITHOUT* ending quote
         End If
      End If
      ParseLineCSVExcel = strBuild           'Return the built string *WITHOUT* ending quote
      Exit Function
   End If

'Need to drop opening "
   If Not ((Asc(chChar) = ASCIIQUOTE) And Len(strBuild) = 0) Then 'Kill opening double quote
      strBuild = strBuild + chChar          'Add the char to the line
   End If
   strLine = Mid$(strLine, 2)          'the input string becomes the "rest" of the line (first char dropped)
   chChar = Left(strLine, 1)
   iStrlen = Len(strLine)                 'Why keep a counter? This is more accurate!
Loop

'last without an ending delimeter exits loop whe the remaining string is 0, so
'   while other field exit the function before loop termination when the fiekd delimeter is found
'   so this last bit takes csre of the last field data that has no ending delimeter
If Len(Trim(strBuild)) > 0 Then
   ParseLineCSVExcel = strBuild
Else
   ParseLineCSVExcel = ""
End If
Exit Function

ParseLineCSVExcelOops:
   MsgBox Str(Err.Number) + " " + Err.Description, "Parser Error"
'   Debug.Print strBuild

End Function

Revised   Jan 13, 2010