Stephen Lebans Code Puzzle

#1 (**permalink**) 28-Jul-2006, 08:25 AM

Hi All

I recently downloaded some code from Stephen Lebans Web site to convert
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/information-technology/12040-stephen-lebans-code-puzzle.html
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=12040
Access reports into PDF files (which is brilliant by the way). I noticed that
the following code snippet is used occasionally :-

If Len(mUncompressedSnapFile & vbNullString) > 0 Then

I don't quite understand the reason for the vbNullString in this code, could
anyone explain it. The variable 'mUncompressedSnapFile' is a normal string
variable.

--
Peter Hibbs

*

#2 (**permalink**) 28-Jul-2006, 08:25 AM

You sure mUncompressedSnapFile is a string, and not a variant?

When it's possible that a value could be either a zero-length string ("") or
Null, it's more efficient to use

If Len(mUncompressedSnapFile & vbNullString) > 0 Then

Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=12040
than

If Not IsNull(mUncompressedSnapFile) Then
If Len(mUncompressedSnapFile) > 0 Then

or

If Not IsNull(mUncompressedSnapFile) Then
If mUncompressedSnapFile <> "" Then

In other words, what Stephen's doing there is making sure that
mUncompressedSnapFile contains a non-blank string.

--
Doug Steele, Microsoft Access MVP
http://I.Am/DougSteele
(no private e-mails, please)

"Peter Hibbs" wrote in message
news:59E4A3FA-2027-485C-800E-D45D69A775B1@microsoft.com...
> Hi All
>
> I recently downloaded some code from Stephen Lebans Web site to convert
> Access reports into PDF files (which is brilliant by the way). I noticed
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=12040
> that
> the following code snippet is used occasionally :-
>
> If Len(mUncompressedSnapFile & vbNullString) > 0 Then
>
> I don't quite understand the reason for the vbNullString in this code,
> could
> anyone explain it. The variable 'mUncompressedSnapFile' is a normal string
> variable.
>
> --
> Peter Hibbs

#3 (**permalink**) 28-Jul-2006, 08:25 AM

I'm guessing that originally Stephen declared it as a variant.

--

Terry Kreft

"Peter Hibbs" wrote in message
news:59E4A3FA-2027-485C-800E-D45D69A775B1@microsoft.com...
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=12040
> Hi All
>
> I recently downloaded some code from Stephen Lebans Web site to convert
> Access reports into PDF files (which is brilliant by the way). I noticed
that
> the following code snippet is used occasionally :-
>
> If Len(mUncompressedSnapFile & vbNullString) > 0 Then
>
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=12040
> I don't quite understand the reason for the vbNullString in this code,
could
> anyone explain it. The variable 'mUncompressedSnapFile' is a normal string
> variable.
>
> --
> Peter Hibbs

#4 (**permalink**) 28-Jul-2006, 08:26 AM

Hi Douglas and Terry

The variable in question is definitely declared as a String, however,
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=12040
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=12040
looking through the rest of the code I notice that this method is also used
against values that are passed as in-line variables in Functions which could
be Null values (maybe). Perhaps Stephen always uses the same technque for
checking a zero length string without worrying about what type of variable it
is.

Anyway, thanks for the information.

--
Peter Hibbs

#5 (**permalink**) 28-Jul-2006, 08:26 AM

Michael Kaplan told me this was the most efficient method to check for a
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=12040
zero length string. I've been doing it ever since.
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=12040

--

HTH
Stephen Lebans
http://www.lebans.com
Access Code, Tips and Tricks
Please respond only to the newsgroups so everyone can benefit.

"Peter Hibbs" wrote in message
news:8DB38BC9-7E8F-423C-9CF6-978B2CA89582@microsoft.com...
> Hi Douglas and Terry
>
> The variable in question is definitely declared as a String, however,
> looking through the rest of the code I notice that this method is also
> used
> against values that are passed as in-line variables in Functions which
> could
> be Null values (maybe). Perhaps Stephen always uses the same technque for
> checking a zero length string without worrying about what type of variable
> it
> is.
>
> Anyway, thanks for the information.
>
> --
> Peter Hibbs
>

#6 (**permalink**) 28-Jul-2006, 08:26 AM

Yes, I can see that as
"" & vbNullString = vbNullString

and there has been a long discusion elsewhere as to why testing for
Len(vbNullString) is more efficient than testing for Len("").

--

Terry Kreft

"Stephen Lebans"
wrote in message news:u5XvhfLmGHA.2056@TK2MSFTNGP03.phx.gbl...
> Michael Kaplan told me this was the most efficient method to check for a
> zero length string. I've been doing it ever since.
>
> --
>
> HTH
> Stephen Lebans
> http://www.lebans.com
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=12040
> Access Code, Tips and Tricks
> Please respond only to the newsgroups so everyone can benefit.
>
>
> "Peter Hibbs" wrote in message
> news:8DB38BC9-7E8F-423C-9CF6-978B2CA89582@microsoft.com...
> > Hi Douglas and Terry
> >
> > The variable in question is definitely declared as a String, however,
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=12040
> > looking through the rest of the code I notice that this method is also
> > used
> > against values that are passed as in-line variables in Functions which
> > could
> > be Null values (maybe). Perhaps Stephen always uses the same technque
for
> > checking a zero length string without worrying about what type of
variable
> > it
> > is.
> >
> > Anyway, thanks for the information.
> >
> > --
> > Peter Hibbs
> >
>
>

#7 (**permalink**) 28-Jul-2006, 08:26 AM

I know, my statement was that "_originally_ Stephen ...".

Anyway Stephens replied elswhere.

--

Terry Kreft

"Peter Hibbs" wrote in message
news:8DB38BC9-7E8F-423C-9CF6-978B2CA89582@microsoft.com...
> Hi Douglas and Terry
>
> The variable in question is definitely declared as a String, however,
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=12040
> looking through the rest of the code I notice that this method is also
used
> against values that are passed as in-line variables in Functions which
could
> be Null values (maybe). Perhaps Stephen always uses the same technque for
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=12040
> checking a zero length string without worrying about what type of variable
it
> is.
>
> Anyway, thanks for the information.
>
> --
> Peter Hibbs
>