Subject: FAQ: (8/95) comp.lang.basic.visual.* VB/Win Frequently
Asked Questions
Newsgroups: comp.lang.basic.visual.misc
, comp.answers , news.answers
Posted-By: auto-faq 3.1.1.2
Archive-name: visual-basic-faq/windows
Last-modified: 22-Aug-95
Covers VB 4.0 (briefly)
*** ATTENTION ***
A greatly expanded and updated version of this FAQ can now be found on the
WWW at http://puta.gurunet.org/vb/ - you are strongly encouraged to refer
to the WWW version. The WWW version may be "ported" to text and posted to
the VB newsgroups, but there are no definate plans to do this at this time.
Please send all feedback on this document to jansh@telepost.no (Jan S. Haugland)
Please don't send VB questions to the FAQ maintainers' private email account.
VISUAL BASIC FOR WINDOWS (VB/Win)
Frequently asked Questions & Answers
Section IX - B
The following symbols indicates new & updated topics:
[++] means topic is updated in this issue
[**] means topic is new in this issue
Hope this makes it easier for Our Regular Readers ;-)
TABLE OF CONTENTS:
******************
A. PREFACE
1. About this document
2. Where to get the VB/Win FAQ [++]
3. Kudos & comments
B. GENERAL VISUAL BASIC QUESTIONS
1. Does VB/Win make standalone .EXE files?
2. What is the current version of Visual Basic for Windows? [++]
3. Where can I get updated VB and other Microsoft files?
4. Help! I am lost on ftp.microsoft.com.
5. Where can I get good up-to-date information about VB? [++]
6. WWW pages for VB! [**]
7. Are there any examples of commercial applications built using
Visual Basic?
8. Limits of VB?
C. COMMON VISUAL BASIC PROGRAMMING QUESTIONS
1. What's the difference between MODAL and MODELESS forms? [++]
2. When/Why should I use Option Explicit?
3. Why does everybody say I should save in TEXT not BINARY?
4. Is the Variant type slower than using other variable types?
5. How do I make a text box not beep but do something else when I
hit the Enter key?
6. How do I implement an incremental search in list/dir/combo/file
boxes?
7. How do I get the Tab key to be treated like a normal character?
8. How do I make an animated icon for my program?
9. What is passing by reference?
10. I get a "file not found" error on the IIF function when I
distribute by program. Uh?
11. Is there any way to pass a variable to a form apart from using
global variables?
12. How should dates be implemented so they work with other
language and country formats?
13. Can a VB application be an OLE server?
14. How do I dial a phone number without using the MSCOMM VBX?
15. I have [several] megabytes of memory. Why do I get an "out of
memory" error? [++]
16. How do I mimic a toggle button? [++]
17. How do I get my application on top?
18. Is there a way to break long lines in VB code?
19. How do I remove/change the picture property of a control at
design time?
20. Is a [foo] VBX/DLL available as shareware/freeware?
21. How do I make my applications screen-resolution independent?
22. How do I do Peek and Poke and other low-level stuff? [++]
23. Why doesn't "my string" & Chr$(13) do what I want?
24. How do I prevent multiple instances of my program?
25. How do I implement an accelerator key for a text box?
26. How do I force a file dialogue box to reread the currect disk?
27. How do I get the number of free bytes on a disk? [++]
28. Data Control missing from toolbox when I use VB under NT 3.5.
Huh?
D. ADVANCED VISUAL BASIC PROGRAMMING ISSUES
1. How do I tell when an application executed using the SHELL
command is finished?
2. How do I access C style strings?
3. How can I change the printer Windows uses in code without using
the print common dialog? How can I change orientation?
4. Any tips for speeding up VB?
5. How do I speed up control property access?
6. How much gain in performance will I get if I write my number
crunching routines in C instead of Visual Basic?
7. How do you make a TEXTBOX read only? Or, how do I prevent the
user from changing the text in a TEXTBOX?
8. How can I create a VBX?
9. How do you change the system menu (on the Control-Menu Box)?
10. How do I play MID, WAV or other multimedia files?
11. How can I call a 'hidden' DOS program from VB?
12. How do I do drag & drop between applications?
13. How do I use GetPrivateProfileString to read from INI files?
14. How do I implement Undo?
15. How do I create a window with a small title bar as in a
floating toolbar?
16. What is Pseudocode?
17. Does VB support pointers to functions?
18. How do I program the Novell NetWare API from VB?
19. Visual Basic 4 news [**]
20. How do you change the icon and otherwise manipulate the DOS
box?
21. How do I make the mouse cursor invisible/visible?
22. How do I create controls dynamically (at run-time)?
23. How do I set the Windows wallpaper at runtime?
24. How do I call help files from a VB program? [**]
E. CALLING THE WINDOWS API AND DLLs IN GENERAL
1. What is the Windows API?
2. How do I call a DLL?
3. What about DLL calls that require callbacks?
4. Tips for calling DLLs (such as the Windows API)
F. VISUAL BASIC AND DATABASES
1. Why can't I use an index with my VB accessed database?
2. "Can't find installable ISAM" or Why does my compiled VB
database app generate an error when it ran just fine in the
design environment?
3. Is the Access Engine and Visual Basic Pro good enough for
database work?
4. How do you avoid the "Invalid use of null" error when reading
null values from a database?
5. What is "NULL"?
6. How can I access a record by record number?
7. How about Access 2.0 compatibility?
8. Tips for VB database programming:
9. How come I get a "No Current Record" error when I use a a Data
Control on an empty table?
10. How can I speed up my VB database application?
11. How do I get a bitmap picture in a field in an Access
database?
12. What is "Reserved Error -1209"?
13. "Cannot perform operation. illegal.." with Paradox 3.5
table(s)
14. I'm getting error message "Reserved Error [-nnnn] ("There is
no message for this error")" from Jet Engine 2.0. Huh?
15. Why do I get "object not an array" when I try reference the
fields of a global object variable which I have set to a table?
16. Steps for securing an Access 2.0 database [**]
G. DISTRIBUTING VISUAL BASIC APPLICATIONS
1. What are some tips for using Setup Wizard?
2. Are there restrictions on what I can distribute with my VB
program?
3. What alternatives to setup wizard do I have?
4. Do I need to worry about users who have Progman replacements
such as Norton Desktop and PC Tools?
5. Can I distribute my app without vbrunXXX.dll?
6. Why won't my setup program install commdlg.dll et. al.?
7. Where do I install VBXs and DLLs?
H. MISCELLANEOUS TIPS AND INFORMATION
1. Multiple identifiers after the DIM statement can be confusing
2. "Clean up" your project before final EXE compilation.
3. Multiple END statements can be dangerous; or, The program that
refused to terminate.
4. What are the latest versions of the various files used by VB?
I. VISUAL BASIC FOR APPLICATIONS (VBA)
1. Any tips for VB/Win 3 programmers moving to VBA?
2. Does VBA support VBXs?
3. How do I access properties on my dialog boxes in VBA?
4. How do I use database routines from Excel VBA?
A. PREFACE
1. About this document
This document is a compilation of frequently asked questions and
their answers about Visual Basic for Windows and Visual Basic for
Applications which have been gathered from posts to the
comp.lang.basic.visual.* newsgroups. Although efforts have been
made to find obvious errors, there is no guarantee that the
information in this document is error-free. Neither the FAQ
maintainer nor anyone else associated with this document assume
ANY liability for the content or use of this document. If you find
any errors, please report them to the address given below.
This FAQ document is protected by international copyright
regulations. Permission is granted to distribute it freely, both
in electronic and written format, provided no charge is made.
Also, do not make changes to this document without the consent of
the maintainer. Usenet netiquette applies.
2. Where to get the VB/Win FAQ [++]
Most FAQs (including this one) are available at the anonymous ftp
archive site "rtfm.mit.edu". All parts of the VB FAQ may be found
here:
ftp://rtfm.mit.edu/pub/usenet/comp.lang.basic.visual.misc/
**Alternative FTP Sites**:
The following are alternative sites to rtfm:
North America: ftp.uu.net /usenet/news.answers
Europe: ftp.uni-paderborn.de /pub/FAQ
ftp.Germany.EU.net /pub/newsarchive/news.answers
grasp1.univ-lyon1.fr /pub/faq
ftp.win.tue.nl /pub/usenet/news.answers
ftp.sunet.se /pub/usenet
Asia: nctuccca.edu.tw /USENET/FAQ
hwarang.postech.ac.kr /pub/usenet/news.answers
(FYI: "rtfm" stands for "Read The ******* Manual". I kid you
not!)
[Andre van Meulebrouck (vanmeule@ils.nwu.edu)]
You can also have the VB FAQs e-mailed to you by sending a message
to
"mail-server@rtfm.mit.edu" with ONLY the text
send usenet/comp.lang.basic.visual.misc/*
in the BODY of the message.
Alternative mailservers for those who have no ftp access
ftpmail@decwrl.dec.com or ftpmail@cs.uow.edu.au
bitftp@pucc.princeton.edu or ftpmail@lth.se
bitftp@dearn or to bitftp@vm.gmd.de (Europe only)
ftpmail@ftp.uni-stuttgart.de
ftpmail@grasp.insa-lyon.fr or ftpmail@ieunet.ie
bitftp@plearn.edu.pl or bitftp@plearn (Europe)
ftpmail@doc.ic.ac.uk or ftpmail@sunsite.unc.edu
[thanks to Jakob Faarvang (jakobf@apexsc.com)]
For all mailservers:
Use the "index" command to get a list of files available at the
site.
Use the "help" command to get more detailed instructions.
(NOTE: commands are in BODY of mail message!)
Note that a Web-browser like Netscape or Microsoft Internet
Explorer easily can access an ftp site, view and download files.
The ftp address on the top of this point (ftp://...) is formatted
for these browsers; just copy and paste the text directly into the
"URL" line.
There is currently work going on to make these available in HTML
format (for Web-browsers). This work is done by Peter Millard
<millard@buffnet.net>. Look at:
http://www.buffnet.net/~millard/vblinks.htm
or go directly to the copies of his HTML FAQ's (when finished!):
http://www.buffnet.net/~millard/vbgenfaq.htm
http://www.buffnet.net/~millard/vbdosfaq.htm
3. Kudos & comments
In this document, whenever a long line of code must be split into
two or more lines of text in the code examples, a | symbol will
precede each line which should be appended to the line above it.
As the FAQ maintainer, I don't have time to explore all of the
aspects of Visual Basic. Neither have I time or knowhow to
personally answer direct technical questions thoroughly. I rely on
your submissions to improve the quality and inclusiveness of this
document. If you have found a VB hint, tip, trick, work-around,
etc., please write it up and send it to me!
Jan Steinar Haugland (jansh@telepost.no), VB/Win FAQ maintainer
Please note that my first language is not English. You can safely
ignore all typos, but if you find an error that is so embarrassing
you can't help pulling your hair and screaming loud, just send me
a note and I'll correct it quietly. OK?
This document is a collective effort! I would like to thank all
contributers, and also all those who have given constructive
feedback. This FAQ is now widely distributed in the net community.
Special thanks to the following people who have made many and
invaluable contributions to the VB/Win FAQ: Kris Nosack (the
previous maintainer), Peter Millard, Nic Gibson, Mr. "D" (the
anonymous contributor), George Tatge (gat@csn.org), Andy Dingley
(dingbat@codesmth.demon.co.uk), Ayn Shipley (ashipley@hookup.net)
and those I may have forgotten (sorry).
John McGuire (jmcguire@jax.jaxnet.com), a longtime VB user,
recently went through the FAQ and found lots of things worth his
comments. Many of his corrections and suggestions are implemented
throughout. Thanks!
Everybody: Your help is GREATLY appreciated!
B. GENERAL VISUAL BASIC QUESTIONS
1. Does VB/Win make standalone .EXE files?
VB/Win produces .exe files, but they are not standalone. All
VB/Win programs must be distributed with the VBRUNx00.DLL file
(where x is the major version number). This DLL must accompany all
VB/Win programs, but only one such file should reside on every
system where VB programs are used.
2. What is the current version of Visual Basic for Windows? [++]
VB/Win is just between version 3.0 and 4.0 as of writing this. 4.0
is about to be released around the same time as Windows 95. This
will contain both a 16-bit and a 32-bit (for NT and Win95) version
of the developing environment and the intergrated compiler.
3. Where can I get updated VB and other Microsoft files?
Microsoft Software Library (MSL) is accessible from the following
services:
- Compu$erve
GO MSL
Search for <filename.EXE>
- Microsoft Download Service (MSDL)
Dial (206) 936-6735 to connect to MSDL
- Internet (anonymous FTP)
ftp ftp.microsoft.com
Change to the \softlib\mslfiles directory
(There are a LOT of files in this directory! It is not
advisable to list all the files unless you have good time.
See map below.)
4. Help! I am lost on ftp.microsoft.com.
You no longer have to be! The site have been reorganised, and
you'll find the file DIRMAP.TXT in root (or whatever it's called
on a 3.5 NT server).
NOTE: Directory and file names at ftp.microsoft.com are NOT case
sensitive.
Thanks to Richard Mason (richard@whitney.demon.co.uk) for the map
he made for us before this long overdue reorganisation, and thanks
for bringing this to my attention.
5. Where can I get good up-to-date information about VB? [++]
If you do any VB programming at all, you really should get the
latest copy of the Microsoft Knowledge Base from one of the
sources listed above! The filename is VBKB.EXE or VBKB_FT.EXE for
the version with full text searching. The Knowledge Base is a
Windows help formatted document that is updated almost monthly.
(Beware: The files are huge!)
The EXE files on ftp.microsoft.com (and other places) are simple
self-extracting files. They don't do any automatic updating of
your system, just dump the file(s) inside them in the current
directory on your disk, uncompressed and ready for use. Just
replace the old files on your system with the new files (same
name, usually).
This FAQ (ahem) is a pretty good source as a digest of many of the
VB issues that are discussed in the comp.lang.basic.visual.*
newsgroups, but as such the information contained in this FAQ may
not have been thoroughly tested or verified.
For easier access to and use of this FAQ document, get the Windows
Help file format FAQ doc by anonymous ftp to quasar.sba.dal.ca and
look under /www/hlp. The .HLP version is made by Tim Roberts
(TJR@SBACOOP.SBA.DAL.CA). This is HIGHLY RECOMMENDED.
Dave McCarter puts out a nice Windows help formatted document
called "Visual Basic Tips and Tricks". A good resource with
information that isn't found in the Knowledge Base. It can be
found by anonymous ftp to ftp.cica.indiana.edu
/pub/pc/win3/programr/vbasic/ as VBTIPS??.ZIP, where '??' is the
version number (yes, get the one with the highest number).
[[ Mark Schoonover has started a monthly magazine called _VBWin
Programmer's Magazine_ that is compiled around the Discussion of
Microsoft Visual Basic and Related Issues mailing list. This
magazine is available at the usual ftp sites like cica and at his
BBS (619) 571-2846. Mark can be contacted at schoon@cts.com. It
also has its own anonymous ftp site: ftp.cts.com in the
/pub/schoon/VBWM.Issues directory. - ED: this appears to be down,
alas. ]]
Jakob Faarvang (jakobf@apexsc.com) maintains the useful CLBV
Digest:
http://www.apexsc.com/vb/clbv-digest/
and
ftp.apexsc.com:/pub/cgvb/clbv-digest/
Address for him regarding CLBV Digest is clbv-digest-
editor@apexsc.com
There is presently an effort to put together a VB code library so
that VB users can share their best - and trickiest - programming
work. The code library project is being spear headed by Hein Ragas
who has managed to get a directory on CICA for code snippets to be
deposited. Stayed tuned to comp.lang.basic.visual.misc for more
information.
There's a VISBAS-L mailing list for Visual Basic (Thanks to David
Liden (DL9U@Virginia.EDU) for tracking it down for me when it
moved). You can subscribe to this mailing list by sending an email
to
listserv@listserv.tamu.edu
Place the following text in the *body* of the message (no, not the
subject line):
SUB VISBAS-L Real Name
Where Real Name is just that, *your full real name* not your email
address. Note that the traffic on this list may overflow your
mailbox if you have a limited mail buffer. Expect around 40-50
messages every weekday, a bit less during weekends. Also, to
unsubscribe, do as above but with "UNSUB" in the body of the
message to the LISTSERV address, *not* to the VISBAS-L list
address itself (Believe it or not, we usually receive 2-3
sub/unsub mails evur day on the list, and we're really fed up!)
Also, this mail server was split and a new list called VBDATA-L
was made for Vb database (Jet) related topics. Same procedure for
registering (SUB VBDATA-L Real Name).
The address for the MS ACCESS listserver is
listserv@indycms.bitnet or listserv@indycms.iupui.edu The list
name is ACCESS-L. To subscribe, you follow the same procedure as
for the other lists.
Sorry, I know no mailservers or other Internet resources dedicated
to VBA specifically. Send me any information you may have, and
I'll bring it on.
There are several Usenet newsgroups dedicated to MS Windows
programming and use. In fact, far too many to list here :-)
NOTE: PLEASE don't post VB stuff to comp.lang.visual. This group
has *nothing* to do with Visual Basic, and the academics
discussing "real" visual programming there are very, very annoyed
at what they call "quasi-visual" stuff and postings about those
languages to their group.
If you have a Compu$erve account, you will find a forum for Visual
Basic there, including some support from Microsoft:
MS BASIC Forum (GO MSBASIC)
Message Sections Available: Libraries Available:
1 Forum News/Info 1 MS Info and Index
2 Setup Wizard/Kit 2 Setup Wizard/Kit
3 Data Access Objects 3 Data Access Objects
4 The Data Control 4 The Data Control
5 Programming Issues 5 Programming Issues
6 ODBC Connectivity 6 ODBC Connectivity
7 SQL Queries 7 SQL Queries
8 ProEdition Controls 8 ProEdition Controls
9 Calling API's/DLL's 9 Calling API's/DLL's
10 Using OLE/DDE 10 VBWIN-ODBC/Database
11 MSCOMM control 11 MSCOMM control
12 MCI/MAPI controls 12 MCI/MAPI controls
13 DOS Visual Basic 13 DOS Visual Basic
14 DOS and Mac Basic 14 DOS and Mac Basic
15 Suggestions/Mktg. 15 Suggestions/Mktg.
16 CDK 16 CDK
17 3rd Party Products 17 3rd Party Products
There are magazines dedicated to VB. The best known is Fawcett
Technical Publications' _Visual Basic Programmer's Journal_
(VSPJ). Phone 800-848-5523 (for US credit card orders) or 303-541-
0610 (int'l and US other orders), Email 74003.224@compuserve.com
to Shirley Modric for subscription info. Address is 280 Second
Street, Suite 200, Los Altos, CA 94022-3603 USA.
From Randy Coates (rcoates@telerama.lm.com):
I currently subscribe to "Inside Visual BASIC for Windows" from
the Cobb Group. Although it is a helpful monthly paper (about 14
pages per publication), I find it to be overpriced when compared
to VB Programmers Journal. Here is the information anyway:
Domestic $59/yr ($7.00 each); Outside US $79/yr ($8.50 each)
Phone: Toll Free: 800-223-8720), Local: 502-491-1900, Customer
Relations Fax: 502-491-8050, Editorial Department Fax: 502-491-
4200. Address: _Inside Visual BASIC for Windows_, 9420 Bunsen
Parkway, Suite 300, Louisville, KY 40220.
(Note: for completeness other VB magazines should be listed, and I
would like to receive info on those!)
6. WWW pages for VB! [**]
Carl 'n Gary's Visual Basic HomePage is a good place to start:
http://www.apexsc.com/vb/
This page has hotlinks to lots of goodies, including the FAQs,
clbv.* archives (with search tool), etc. Send any e-mail inquiries
(about the page!) to:
vb-admin@apexsc.com
[Gary Wisniewski (gary@apexsc.com)]
7. Are there any examples of commercial applications built using
Visual Basic?
Profit by Microsoft was written mostly in Visual Basic. In fact,
Profit was one of three programs selected as PC Magazine's
Editor's Choice among Windows small business accounting packages.
Most of the current version of Quicken was written in VB2. The
viewer/launcher/installer in the oh-so-popular Way Cool [Topic]
for Windows series of CD-ROMs was written in VB3.
Microsoft uses VB extensively for smaller utilities. 3 of the
small apps in the Windows and Windows for Workgroups Resource
Toolkits are written in VB. Also, if you have the Microsoft
Bookshelf CD-ROM, you will notice that the MVOPTION.EXE program,
which is an "options" program for MS Viewer, is created in VB.
Note: The existence of VBX files in a package doesn't ecessarily
mean that it was written in VB. The most popular C++ compilers
also support VBXes.
8. Limits of VB?
Are you kidding? VB have *no* limitations... Uh, yeah ;-)
For starters:
* It's not a true compiler, hence it's slow for non-interface
stuff (it's of
course slow for interface stuff as well, but that's *Windows*
not VB)
* It's not really object-oriented (Try looking for the parent of
ie. a line
control, and you'll wonder why it has no hWnd - SpyWorks is an
add-on you
may need if this is annoying)
* A statement must be on a single line! (Note: Fixed in VB4!!!!)
* No arrays of constants.
* Your Complaint Here!
An enormous amount of contributers to this topic! Can you guess
why?
[Entry suggested by Andre van Meulebrouck (vanmeule@netcom.com)]
C. COMMON VISUAL BASIC PROGRAMMING QUESTIONS
1. What's the difference between MODAL and MODELESS forms? [++]
MODAL forms are forms which require user input before any other
actions can be taken place. In other words, a modal form has
exclusive focus in that application until it is dismissed. When
showing a modal form, the controls outside this modal form will
not take user interaction until the form is closed. The internal
MsgBox and InputBox forms are examples of modal forms. To show a
form modally, use the syntax:
MyForm.SHOW 1
MODELESS forms are those which are shown but do not require
immediate user input. MDI child forms are always modeless. To show
a form modeless, use the syntax:
MyForm.SHOW
(Thanks to John M. Calvert (calvertj@magi.com) for correcting a
slightly embarrassing mistake in previous versions of this topic)
2. When/Why should I use Option Explicit?
Option Explicit forces you to declare all variables before using
them. Opinions vary greatly on this subject. The main reason to
use the OPTION EXPLICIT statement at the top of all modules is to
minimize the amount of bugs introduced into your code by
misspelling a variable name. Most variants of BASIC (including VB)
have the capability to create variables 'on the fly' (without any
declarations). This capability can be a double edged sword.
At the minimum, some suggest using the DEFINT A-Z statement in leu
of OPTION EXPLICIT. This statement will cause any variables which
are created on the fly to be created as integers as opposed to
variant (VB 3.0) or single precision (VB 1.0 and 2.0). (Integers
take up less memory).
The OPTION EXPLICIT statement causes VB to 'disable' its ability
to create variables on the fly. Thus, all variables must be
declared using a DIM or REDIM statement. All variables not
declared will cause an error when the OPTION EXPLICIT statement is
used. This will eliminate bugs caused by a misspelled variable.
The option works module-wide, so you can have some modules with
and some without this option in your project.
3. Why does everybody say I should save in TEXT not BINARY?
Actually, saving in binary mode is a bit faster, so why do we
recommend you to save in text?
If you save the source and the project as text, it becomes ASCII
(or really, ANSI) code that you can edit with any text editor or
(if you are careful when you save) word processor. If you save in
binary, only the VB development environment, current or later
versions, will understand the code. The Setup Wizard can not scan
binary projects. Also, source documenters and other programming
tools usually require text mode. If you use text, you can use a
simple text editor (ie. notepad) to cut and paste code from other
source/form modules into your current project. Some 'tricks' (like
making an array of 1 control into a single non-array control
again) is easily done with an editor but not that easy in the
environment. If you want to print your project to paper the
file|print option in the VB environment is often not good enough;
you may want to import the text files into your word processor.
And, finally, if something goes wrong (only one byte is changed!)
you may be out of luck in binary mode. In text mode you will more
easily be able to fix it.
4. Is the Variant type slower than using other variable types?
Generally, yes, if we are talking numeric variable types. The
Variant type also increases memory overhead. To test the speed
difference, try the following piece of code in something like a
button_click event and keep the debug window on the screen:
Dim Va As Variant
Dim In As Integer
T1! = Timer
For i% = 1 To 32766
Va = i%
Next i%
T2! = Timer
Debug.Print "With variant: "; Format$((T2! - T1!), "0.0000")
T1! = Timer
For i% = 1 To 32766
In = i%
Next i%
T2! = Timer
Debug.Print "With integer: "; Format$((T2! - T1!),"0.0000")
This test shows (on our test system) that integers are ~60%
faster! However, for strings there where no real difference, or in
some instances, variants were faster than strings for routines
with heavy conversion usage. For the best result in your
application, test your routines directly.
5. How do I make a text box not beep but do something else when I
hit the Enter key?
Put "something else" in your _KeyPress event, depending on what
you really want. This code example makes *nothing* happen, for an
extended period of time:
Sub Text1_KeyPress (KeyAscii As Integer)
If KeyAscii = 13 Then '13 is Key_Return
KeyAscii = 0
End If
End Sub
This might not be a very nice thing to do, since your users
usually have some intention when they press Enter. Often they will
want to jump to the next control, like the Tab key does. To have
the Enter key emulate the Tab key action, you will need to add the
line 'SendKeys "{tab}"' above 'KeyAscii=0' in the example above
(Yes, I thought KeyAscii=9 works but it doesn't! Tab is obviously
handled by Windows on a lower level).
By the way, you'll also find this in the Microsoft VB Knowledge
Base (see KB Q78305 and Q85562).
Note: If MultiLine=True you will *not* want to disable the normal
behaviour of the Enter key.
6. How do I implement an incremental search in list/dir/combo/file
boxes?
This is your lucky day. Dan Champagne (Dan_Champagne@dell.com)
made some VB code (no DLLs are necessary!) which easily provides
this feature for your applications:
' Code by Dan Champagne
' 4/18/94
' This code can be used to do an incremental search in either a
' list box, dir, combo, or a file box. The following code is set
' for a file box called FILE1. To make it work with a list box, or
' a file box with a different name, change all occurences of FILE1
' with whatever you or VB has named your list, combo, dir, or file box.
' There are two places where you will need to change these. They are
' on the last couple of lines in the KeyPress code.
' Also, thanks to John Tarr for helping debug the code.
'In a .BAS file, add the following:
'searchme$ is a global vaiable that will keep track of what the
'user has typed so far.
Global searchme$
'The following needs to be on one line.
Declare Function SendMessageBystring& Lib "User" ALIAS
|"SendMessage" (ByVal hWnd%, ByVal wMsg%, ByVal
|wParam%, ByVal lParam$)
Global Const WM_USER = &H400
Global Const LB_SELECTSTRING = (WM_USER + 13)
Global Const LB_FINDSTRING = (WM_USER + 16)
'In File1 under keydown, add the following:
'This checks if the user has pressed the up or down arrow.
'If they have, reset searchme$ to "".
If KeyCode = 40 Or KeyCode = 38 Then
searchme$ = ""
End If
'In File1 under lostfocus, pathchange, patternchange, and click add:
'If the user has done any of the above, reset the searchme$
'string.
searchme$ = ""
'In File1 under keypress add:
Dim result&
Select Case KeyAscii
Case 8 'Backspace
If searchme$ <> "" Then
searchme$ = Left$(searchme$, Len(searchme$) - 1)
Else
File1.ListIndex = 0
End If
KeyAscii = 0
Exit Sub
Case 27 'Escape
searchme$ = ""
KeyAscii = 0
Exit Sub
Case 13 'Enter
searchme$ = ""
KeyAscii = 0
Exit Sub
Case Asc("a") To Asc("z"), Asc("A") To Asc("Z"), Asc("'"),
|Asc("."), Asc(" "), Asc("0") To Asc("9")
searchme$ = searchme$ & Chr$(KeyAscii)
KeyAscii = 0
End Select
result& = SendMessageBystring(FILE1.hWnd, LB_FINDSTRING,
|0, searchme$)
If result& = -1 Then
searchme$ = Left$(searchme$, Len(searchme$) - 1)
Else
result& = SendMessageBystring(FILE1.hWnd, LB_SELECTSTRING,
|-1, searchme$)
End If
7. How do I get the Tab key to be treated like a normal character?
You must set TabStop = False for ALL controls on the active form.
Then you will be able to insert "tab" (chr 9) characters in
controls like the text box.
If you feel you need the Tab key to behave "normal" (ie. jump to
next control) outside this specific control, it is trivial to
emulate its functionality in code:
Sub Command1_KeyDown (KeyCode As Integer, Shift As Integer)
If KeyCode = 9 Then
If Shift = 0 Then
Command2.SetFocus 'Tab=Next control
ElseIf Shift = 1 Then
Command3.SetFocus 'Shift-Tab=Prev.ctrl.
End If
End If
End Sub
...etc.
8. How do I make an animated icon for my program?
For an example on how you change the icon for your application as
it is displayed when it is minimized, see the example REDTOP in
the \samples\picclip directory for VB/Win 3 Pro. This demonstrates
a fancy animated icon.
9. What is passing by reference?
Arguments are either passed by reference or by value. When they
are passed by value, they cannot be changed by the procedure or
function they are passed to. They *can* be altered when passed by
reference, since passing by reference is just passing the address.
Note that procedures are less strict about variable types when you
use BYVAL. If you declare that your Sub takes a Variant, VB takes
that seriously and gives a nasty "mismatch error" if you try to
pass ie. a string to it. Make it ByVal (at the cost of some speed)
and your sub will be more tolerant.
Also note the following nasty trap: Arguments are passed by
reference unless enclosed by parentheses or declared using the
ByVal keyword. [VBWin Language Ref., p. 55]
10. I get a "file not found" error on the IIF function when I
distribute by program. Uh?
There's a documentation error, since the manual does not tell you
that the IIF function requires the file MSAFINX.DLL to be
distributed with your application. No, IIF is not financial (I
should know, I study finance right now, or at least I should be
doing that ;-] ).
11. Is there any way to pass a variable to a form apart from using
global variables?
The standard workaround is to put an invisible text box (or
caption or any other control that suits your use.) on the target
form and access it by Form.textbox = "value". Then you can use the
Change event of that control to do anything you want in that form.
Also, check out the .Tag property which is a "what-you-want"
property where you can hook any string you want onto a control.
This property can also be accessed from other modules.
[Dave Mitton (mitton@dave.enet.dec.com)]
Perhaps a more elegant and flexible way is to implement a stack
with similar routines. I've done this for a math project, but this
stack was rather complicated and special purpose (and inspired by
HP calculators, of whihc I'm a great fan).
Jan G.P. Sijm (jan.sijm@intouch.nl) have implemented some routines
for general stacks:
'-----------------------------------------------------------------
---
Option Explicit 'Variable declarations
required
Dim m_vStack() As Variant 'Stack of variant types
'*-------------
'* This function will pop a value of a stack of variant
'* values. The value to be popped (e.g. the variable it
'* is assigned to) must have one of the basic variable
'* types that Visual Basic supports. The type of the
'* return value is determined by the type of the variable
'* it is assigned to.
'*
'* Input : None
'* Modifies : m_vStack, Stack of variant's
'* Return : Value of last pushed variant
'*-------------
Function stkPop () As Variant
Dim iM As Integer
iM = UBound(m_vStack) 'Get current stack size
stkPop = m_vStack(iM) 'Pop value from stack
iM = iM - 1 'Decrement number of
elements
ReDim Preserve m_vStack(iM) As Variant
End Function
'*-------------
'* This function will push a value onto a stack of
'* variant values. The value to be pushed must have one
'* of the basic variable types that Visual Basic supports
'*
'* Input : vValue, Value to be pushed
'* Modifies : m_vStack, Stack of variant's
'*-------------
Sub stkPush (ByVal vValue As Variant)
Dim iM As Integer
On Error Resume Next 'Trap for undimensioned
array
iM = UBound(m_vStack) 'Get current array size
iM = iM + 1 'Increment number of
elements
ReDim Preserve m_vStack(iM) As Variant
m_vStack(iM) = vValue 'Push value on stack
End Sub
'This is a short example of how the stack routines can be used in
a
'Visual Basic program. This example will push three parameters
onto
'the stack. A modal dialog is displayed. The dialog will pop the
'parameters from the stack and set edit controls with the values.
Sub ShowDialog()
'
' Push the parameters for the dialog
' onto the stack and display the dialog
'
stkPush sName
stkPush sStreet
stkPush sCity
dlgPerson.Show MODAL
End Sub
Form_Load()
'
' Pop the parameters of this dialog from the
' stack in REVERSED ORDER and place the values
' in the appropriate edit controls.
'
dfCity.Text = stkPop()
dfStreet.Text = stkPop()
dfName.Text = stkPop()
End Sub
'-----------------------------------------------------------------
---
12. How should dates be implemented so they work with other language
and country formats?
If you use ie. MM/DD/YY format dates in a program, you will get
either a runtime-error (ie. month>12) or the wrong date (ie. March
12 instead of December 3) when your program is used in Europe. And
vice versa, of course. Even Microsoft's own example programs (like
the MAPI sample) make this stupid mistake and fail miserably. Use
the Format command to make sure you get the date you want. For
example:
strTodaysDate = Format[$](Now, "Short Date")
As a side note, Microsoft has taken much heat on the newsgroup for
VB's bad support for internationalization! Just try to make a date
literal in source code that works everywhere as a little exercise.
Answer elsewhere in this document. No prizes :-)
13. Can a VB application be an OLE server?
No. You'll have to use an external DLL/VBX. If you see any
examples, please tell the newsgroup.
14. How do I dial a phone number without using the MSCOMM VBX?
The MSCOMM VBX that comes with VB/Pro is great for creating
communication programs, but it's overkill for dialing a phone
number. Try the following code:
PhoneNumber$ = "(123)456-7890"
Open "COM2:" For Output As #1 'or COM1
Print #1, "ATDT" & PhoneNumber$ & Chr$(13)
Close #1
Ian Storrs <exuian@exu.ericsson.se> informed me that he had
experienced problems with this when the VB program was run from a
network drive. A file named "COM1" was created on the disk! Jeff
Rife <jrife@health.org> put in the ":" after COM2 to solve that
problem!
This trick is probably not a good idea for bigger applications,
but it's nice for small personal utilities.
15. I have [several] megabytes of memory. Why do I get an "out of
memory" error? [++]
This problem and its solution(s) should not be applicable to
Windows 95.
Unfortunately, Microsoft has been more famous for memory barriers
than anything else. This is a late descendant of the infamous 640K
barrier that has been plaguing us for years. Although Windows
allows the user to access several megabytes of memory, it uses two
limited (64K) memory areas called User Heap and GDI Heap for some
specific data structures. Go to the Help|About box in Program
Manager to see the percentage of free resources in the *most*
exhausted heap. If these areas are exhausted, you are out of luck.
VB programs are unfortunately rather greedy on these structures.
Windows 4 is supposed to free us from this limitation...
Note that every visible control (ie every button) is a window to
Windows. Every new control takes up some bytes in the precious
User heap.
Also, there is another way to run out of memory in Windows, not
related to VB. Windows requires free Upper Memory Area (UMA, also
called Upper Memory Blocks, not to be confused with High RAM,
which is the first 64K of extended memory) to do certain tasks. If
you use QEMM or DOS 6+ MemMaker and you have many device drivers
(network, etc) this area may have been filled up before you launch
Windows. You will then be unable to start applications, even
though you have plenty of free RAM. The problem can be solved with
careful memory setup, but this is far beyond the scope of this
FAQ.
On a completely unrelated problem: When you run a program with an
outline control with some ATI graphics cards, it may crash with
just that error message. (see Knowledge Base Q100194 PRB: "Some
ATI Video Drivers Hang When Using MSOUTLIN.VBX")
16. How do I mimic a toggle button? [++]
The only "fix" we know for this problem is to use a picture or
image control to mimic the action of a button or button3d control.
You need two bitmaps, one for buttonup and one for buttondown (and
perhaps one more for inactive state). This is a kluge, we know.
Look at the button bar used in the MDINOTE sample program supplied
with VB for an example of this.
17. How do I get my application on top?
To force a form to the front of the screen, do the following
command:
Form1.ZOrder
To make the application *stay* on top, put the Zorder command in a
Timer event repeatedly called, say, every 1000 msecs. This makes a
"softer" on-top than other methods, and allows the user to make a
short peek below the form.
There are two different "Zorder"'s of forms in Windows, both
implemented internally as linked lists. One is for "normal"
windows, the other for real "topmost" windows (like the Clock
application which is distributed with MS Windows). The Zorder
command above simply moves your window to the top of the "normal"
window stack. To make your window truly topmost, use the
SetWindowPos API call like this:
'Make these declares:
Declare Function SetWindowPos Lib "user" (ByVal h%,
|ByVal hb%, ByVal x%, ByVal y%, ByVal cx%, ByVal cy%,
|ByVal f%) As Integer
Global Const SWP_NOMOVE = 2
Global Const SWP_NOSIZE = 1
Global Const FLAGS = SWP_NOMOVE Or SWP_NOSIZE
Global Const HWND_TOPMOST = -1
Global Const HWND_NOTOPMOST = -2
'To set Form1 as a TopMost form, do the following:
res% = SetWindowPos (Form1.hWnd, HWND_TOPMOST, 0, 0,
|0, 0, FLAGS)
'if res%=0, there is an error
'To turn off topmost (make the form act normal again):
res% = SetWindowPos (Form1.hWnd, HWND_NOTOPMOST, 0, 0,
|0, 0, FLAGS)
18. Is there a way to break long lines in VB code?
There is unfortunately no line continuation character in VB/Win
3.0. Excel 5 VBA does, however, use Space+Underscore (" _") as a
line continuation character, and we hope this will be included in
the next version of VB.
There are a few tricks you can use to reduce line length, but
unfortunately there is very little to do with DECLARE statements
which can get very long.
Print your source in landscape :-/
19. How do I remove/change the picture property of a control at
design time?
Mark the (bitmap) or (icon) text in the property window and press
Del or Backspace. "No!" I hear you cry, "It doesn't work". Well,
it does if you first select the object from the combo box at the
top of the Properties Window, and then immediately afterwards
doubleclick (or paint over) the "(bitmap)" text and press Del.
Alternatively, just click on another control, then click back to
the first control. Now Del works. Who said "bug"?
If you want to paste your picture directly into the VB program by
pressing Ctrl-V when you are editing the picture property, you
will have to use a semilar procedure: select the control, select
the property, press Ctrl-V. If you try it again without
deselecting the control first (or selecting it from the combo
box), it doesn't work.
20. Is a [foo] VBX/DLL available as shareware/freeware?
Part 4 of the FAQ is Adam Harris' excellent "Shareware Custom
Controls List". Please consult this list before you post this
question.
The following type of controls are NOT known to be available as
sw/pd/fw for Visual Basic, only as commercial toolboxes (If you
feel like making any of these for VB and sharing it for a modest
fee, you will become very popular!):
a. ZModem communication control/source
b. Rich Text Format-control or other mixed font/word processor
control (rumours indicate that this will be in the Windows 4 API, and
therefor available from VB)
c. Matrix math
If any of these should be available, please tell us.
21. How do I make my applications screen-resolution independent?
There are two methods: Either get a custom control that does the
job for you, or you write lots of complicated code in the Load and
Resize events.
For the first option, check out VideoSoft's $hareware VSVBX.VBX
(download VSVBX.ZIP from Cica or mirrors). It has a will of its
own, as you will experience, but it's generally better than trying
what is described below.
For the brave (or stupid), try to write "screen resolution-smart
code" in the form's Load event. If the form is resizable (normally
it should be), you'll have to put some magic into the Resize event
as well. There are 4 rules of thumb:
a. Do not trust the form's height and width properties. These
measure the entire form, not the client area where your controls are.
To see this in action, create a simple applet with the only code being
in the resize event which resets a line control from 0,0 to the form's
width,height properties. The top left corner is in the client area,
the bottom right corner disappears. The API call GetClientRect will
return the size of the client area in pixels. You can use the screen
object's TwipsPerPixelX and TwipsPerPixelY properties to convert from
pixels to twips. If that's not enough, GetWindowRect will return the
actual size of the entire form, client and non-client areas combined.
GetSystemMetrics will return individual pieces of things like border
width/hight, caption height, etc.
b. Use the TextWidth and TextHeight properties. You can use them
off the form if all your controls share the same font, otherwise use
them off of the given control. I typically do a TextWidth("X") and
TextHeight("X") to get a value which I use as a margin between
controls. I grab these values on startup, and multiply it by 2, 1.5,
.75, .5, .25 to get varying margin sizes, depending on how close or
far apart I want to space things. If your control has an autosize
property, you may want to use it, and then calculate the maximum width
of a control in a given "column" of controls on your screen and
position all of them accordingly.
c. Try not to resize your controls in the resize event. You will
spawn another resize event in the process. Of course, you can use a
flag to determine whether the resize event is the original event or
the spawned one. Using the load event, and setting the forms borders
to fixed minimizes the amount of work you have to do.
d. Make sure you use a consistant scale. I don't even bother with
the scale properties, but instead just convert pixels (from API calls)
into twips and be done with it. If you do use scale properties, be
sure you convert your numbers correctly. I had no end of difficulty
when I failed to convert into twips with one number that was used in a
series of calculations to position controls. Also be sure all your
controls share the same SCALE -- another nasty problem I had before I
gave up on them completely.
[Thanks to our generous anonymous source "D"]
22. How do I do Peek and Poke and other low-level stuff? [++]
VB provides no mechanism for this. There are several 3rd party
pkgs. which provide this. Also, this often comes up in regards to
the comm ports and you can many times do what you want with the
mscomm.vbx.
[George Tatge (gat@csn.org)]
On The Developer Network Library CD, you'll find the following:
VBASM is a Microsoft(R) Visual Basic(R) dynamic-link library (DLL)
that
helps Visual Basic programmers accomplish tasks that are difficult
or
impossible using Visual Basic alone. This sample application
includes
two programs, SNOOPER and TXTALIGN, that demonstrate the DLL's
use.
The DLL contains many low-level routines such as access to real
and
protected mode interrupts, port input/output (I/O), peek/poke,
control
manipulation, and so on. These routines and their associated
functions
include:
* Control Manipulation
vbGetCtrlHwnd, vbGetCtrlModel, vbGetCtrlName, vbRecreateCtrl
* Pointer and Memory
vbGetData, vbGetLongPtr, vbPeek, vbPeekw, vbPoke, vbPokew, vbSAdd,
vbSetData, vbSSeg, vbVarPtr, vbVarSeg
* Byte/Word/Long Manipulation
vbHiByte, vbHiWord, vbLoByte, vbLoWord, vbMakeLong, vbMakeWord
* I/O Access
vbInp, vbInpw, vbOut, vbOutw
* Interrupts
vbInterrupt, vbInterruptX, vbRealModeIntX
* Others
vbGetDriveType, vbShiftLeft, vbShiftRight
[Deane Gardner <deaneg@ix.netcom.com> quotes Microsoft]
There's a shareware package for in/out routines, btw.
23. Why doesn't "my string" & Chr$(13) do what I want?
You need to also add a Chr$(10): "my string" & Chr$(13) &
Chr$(10) will give you a CR and LF.
[George Tatge (gat@csn.org)]
24. How do I prevent multiple instances of my program?
In VB 3, the property App.PrevInstance is set to True if an older
instance of the program already exist.
The following piece of code, stolen from MS KB article Q102480,
will activate the old instance and then terminate itself:
Sub Form_Load ()
If App.PrevInstance Then
SaveTitle$ = App.Title
App.Title = "... duplicate instance." 'Pretty, eh?
Form1.Caption = "... duplicate instance."
AppActivate SaveTitle$
SendKeys "% R", True
End
End If
End Sub
As Robert Knienider(rknienid@email.tuwien.ac.at) informed me, this
piece of code WILL NOT work for non-English versions of MS Windows
where the word for "Restore" does not have "R" as the underlined
word. Replace the "R" in the SendKeys line above with "{ENTER}" or
"~".
Note that you shouldn't prevent multiple instances of your
application unless you have a good reason to do so, since this is
a very useful feature in MS Windows. Windows will only load the
code and dynamic link code *once*, so it (normally) uses much less
memory for the later instances than the first.
25. How do I implement an accelerator key for a text box?
You want to use a label caption to identify a text box and to act
as if it were the text box caption:
Example:
&Label1 [text1 ]
How should I do to set the focus to text1, by typing <ALT>L
Make sure that the TabIndex property for the text box is 1 greater
than the
label's TabIndex. Since a label can't have the focus, the focus
will go to the next item in the tab order, which would be the text
box.
Here's any easy way to set the TabIndex for a busy form. Select
the object that should be last in the tab order and then select
the TabIndex property. Press 0 (zero), click on the next to last
object, press 0, click on the the next object back, press 0, etc.
When you're done, all of the TabIndexes will be in order, because
VB increments all of the higher TabIndexes when you put in a lower
number.
Many thanks to Jonathan Kinnick and Gary Weinfurther that provided
the answer
on the FIDO net echo VISUAL_BASIC.
[Tiago Leal (Tiago.Leal@p25.f1.n283.z2.gds.nl)]
26. How do I force a file dialogue box to reread the currect disk?
If you make a simple dialogue box modelled after common dialogue
(normally you should *use* the common dialogue VBX!), you will
notice that reselecting the diskette drive will not really rescan
the disk. Very annoying to change to C:, and to reselect A: just
to make it read the directory of a new diskette.
To solve this problem, put
drive1.refresh
dir1.refresh
file1.refresh
in the code for the "Rescan" button (or whatever).
27. How do I get the number of free bytes on a disk? [++]
As far as I know, there is three possibilities:
1. SETUPKIT.DLL as mentioned above
2. Arjen Broeze's VBIO.VBX or something like that, with a lot of
options.
3. Make your own DISKINFO.DLL from the example code in VBKB
article Q106553.
See Article Q113590 (or Q106553) in Microsoft's VB KnowledgeBase.
A short extract follows:
Declare Function DiskSpaceFree Lib "SETUPKIT.DLL" () As Long
Dim free_space& ' Holds number of bytes returned from
DiskSpaceFree().
ChDrive "c:" ' Change to the drive you want to test.
free_space& = DiskSpaceFree()
[Geir Tutturen(itfgt@nlh10.nlh.no)]
28. Data Control missing from toolbox when I use VB under NT 3.5.
Huh?
Open the VB.INI file and add these lines under the [Visual Basic]
heading:
ReportDesign=1
DataAccess=1
[Danny Ames (dames@pic.net)]
D. ADVANCED VISUAL BASIC PROGRAMMING ISSUES
1. How do I tell when an application executed using the SHELL
command is finished?
Shell() doesn't really return a task handle, it returns an
instance handle. Any documentation that says otherwise is wrong.
But never mind that; the answer to your question is to use the API
call GetModuleUsage.
'Put this in the general declarations of your form/module
Declare Function GetModuleUsage Lib "Kernel" (ByVal
|hModule As Integer) As Integer
'Here's where you shell out to the other program
intHandle = Shell("PROGRAM.EXE")
Do While GetModuleUsage(intHandle) > 0
DoEvents
Loop
[Kenn Nesbitt, Microsoft Consulting Services (kennn@netcom.com)]
The FindWindow command can also be used (search the Tips help file
for "How VB Can Determine if a Specific Windows Program Is
Running"). I have had to use this when the program I shelled to
unloaded itself and ran a different EXE. My program thought the
shell was done (since the shelled EXE ended), but it really had
just "moved on" to another EXE. Generally, the code in cases like
this must be customized to fit the situation.
[John McGuire (jmcguire@jax.jaxnet.com)]
2. How do I access C style strings?
Use the 'lstrlen' and 'lstrcpy' calls found in the Kernel DLL.
3. How can I change the printer Windows uses in code without using
the print common dialog? How can I change orientation?
You can change the printer the VB 3.0 Printer object is pointing
to programmatically (without using the common dialogs). Just use
the WriteProfileString API call and rewrite the [WINDOWS], DEVICE
entry in the WIN.INI file! VB will instantly use the new printer,
when the next Printer.Print command is issued. If you get the old
printer string before you rewrite it (GetProfileString API call),
you can set it back after using a specific printer. This technique
is especially useful, when you want to use a FAX printer driver:
Select the FAX driver, send your fax by printing to it and switch
back to the normal default printer.
[Hajo Schmidt (hajo@bwl.bwl.th-darmstadt.de)]
It is recommended (and polite, as we're multitasking) to send a
WM_WININCHANGE (&H1A) to all windows to tell them of the change.
Also, under some circumstances the printer object won't notice
that you have changed the default printer unless you do this.
Declare Function SendMessage(ByVal hWnd As Integer,
|ByVal wMsg As Integer, ByVal wParam As Integer,
|lParam As Any) As Long
Global Const WM_WININICHANGE = &H1A
Global Const HWND_BROADCAST = &HFFFF
' Dummy means send to all top windows.
' Send name of changed section as lParam.
lRes = SendMessage(HWND_BROADCAST, WM_WININICHANGE, 0,
|ByVal "Windows")
[Nic Gibson (nic@skin.demon.co.uk)]
To change between landscape and portrait orientation, search of
VBKB_FT on "lands*" finds Article ID: Q80185 "How to Set Landscape
or Portrait for Printer from VB App".
This is an extract:
Declare Function Escape% Lib "GDI" (ByVal hDC%, ByVal nEsc%, ByVal
nLen%,
|lpData As Any, lpOut As Any)
Sub Command1_Click ()
Const PORTRAIT = 1
Const LANDSCAPE = 2
Const GETSETPAPERORIENT = 30
Dim Orient As OrientStructure
Printer.Print ""
Orient.Orientation = LANDSCAPE
x% = Escape(Printer.hDC, GETSETPAPERORIENT, Len(Orient), "",
Null)
Print x%
End Sub
[Ayn Shipley (ashipley@hookup.net)]
4. Any tips for speeding up VB?
Who said "code in C"???? ;-)
a. When SHOWing a form with lots of bound controls, have a blank
frame covering everything. Then, in the Form_Activate event, set the
Frame.Visible = False. This greatly speeds the display of the form and
hides ugly thrashing as the data controls initialize.
[Christopher Biow (biow@cs.umd.edu)]
b. Try to keep any Global definitions to a minimum. Massive numbers
of global variables really seem to slow VB Windows down (besides
chewing up memory). In other words, if you've pasted a lot of stuff
from the globals.txt file, trim all definitions and variables you
don't use in your application.
c. Keep the total number of controls and forms used to a minimum
(you've probably already guessed that).
d. Keep fancy graphics to a minimum (another one you know).
e. Try "pre-processing" in the background (using Do_Events).
Doesn't really speed anything up, but often there is a lot of "idle"
time while the user is selecting menu's, buttons and such - if you can
do some calculations, image loading or whatever during this idle time
your user perceives the application is faster than it really is.
f. Hide often-used forms rather than unloading them. Unloading saves
memory, but it takes longer to re-load a form than to simply "un-hide"
it.
[Tips b to f by Galen Raben (galenr@gr.hp.com)]
The following tip is along the same lines, but with a code sample.
They are provided by Andy Dingley (dingbat@codesmth.demon.co.uk):
You're limited by the system as to how quickly you can go from
calling frmMyForm.Show to being able to type into the controls,
but you can make the form *appear* to display faster. One
technique is to keep forms loaded, and just switch their
visibility on and off. This is heavy on resource usage, and
doesn't help for the first time they're shown.
Most forms have some processing (eg. querying a table to fill a
list box) that goes on when they're first opened, and this is what
causes the most serious delay. It's possible to display the form,
make its controls appear on screen, then do the slow processing
before finally making the form "live". As the user can see things
happening, the perceived delay is less obvious.
Include the following code in your form:
Option Explicit
Dim FirstActivation as integer
Sub Form_Activate
DoEvents 'Allow the _Load event to be seen on screen
If FirstActivation Then
' Do all the slow loading stuff here
If FillComboBox <> 0 Then
Unload Me 'If it all goes horribly wrong, then you
'can call Unload from an _Activate event
'(Which you can't do from the _Load event)
End If
FirstActivation = False
End If
Screen.MousePointer = DEFAULT
End Sub
Sub Form_Load
FirstActivation = True
End Sub
Show the form by using:
Screen.MousePointer = HOURGLASS
frmMyForm.Show MODAL
Bruce Garrett (bruceg@access2.digex.net) had the following tips
from his VBITS 93 notes:
- Polling a control for its properties directly is 10 to 20
times slower then placing the property values you need into
variables and testing the value of the variables.
- Swap tuning: Modules are not loaded until used; put related
code in the same modules, reduce the number of intermodule
calls and keep modules small.
- Binary file I/O is faster then Text/Random.
There was also a lot of discussion about "apparent" speed i.e: how
it looks on the screen as opposed to how fast it's chugging
internally. It was noted that the cute little flashing menu items
and exploding windows in the Mac amounted to a little razzle-
dazzle to distract you from how long it took to actually load
something and get it on the screen. Keeping all your forms loaded
but hidden until needed was suggested. Also the use of progress
indicators and a simple quickly loaded and drawn startup form.
Also preloading data you expect to need.
5. How do I speed up control property access?
Instead of using a property in a loop, you will be better off
using a normal variable in the loop and then assign the variable
once to the property afterwards. Also, when reading a property,
you should read it once into a variable instead of using it in a
loop.
Sometimes it is not possible to simply put contents of a property
into a variable. For example, if you are using a list box or you
need to conserve memory. In these cases you can send the
WM_SetRedraw message to the control to prevent redrawing. You can
typically increase the speed 6-10 times - or even more.
'Add the following declares:
Declare Function SendMessage Lib "User" (ByVal hWnd As
|Integer, ByVal wMsg As Integer, ByVal wParam As
|Integer, lParam As Any) As Long
Const WM_SetRedraw = &HB
'Add this to your code:
Result% = SendMessage(Text1.hWnd, WM_SetRedraw, 0, 0)
'redraw off
'Do your stuff here!
Result% = SendMessage(Text1.hWnd, WM_SetRedraw, 1, 0)
'redraw on
This same method applies to list boxes and other controls.
6. How much gain in performance will I get if I write my number
crunching routines in C instead of Visual Basic?
Probably the best solution to the number crunching problem is to
write the number crunching routines as a custom control or a DLL,
and plug it into a VB app. VB interface handling is not
significantly slower than, say C++, and most of the wait is
associated with Windows.
Some real world experience speaks volumes about this one:
I wrote some time consuming code in VB to solve a combinatorical
(does this word exist in English?) problem. The code consists of
one main recursive function, which calls itself very often. It
took a night to compute a certain problem. I was rather
disappointed and then decided to write the central routine in C++.
It was a 1:1 transcription. The routine was compiled with the MS
C++-Compiler. It took only 22 Minutes for the same problem.
Amazing, isn't it? The routine doesn't do any floating point
arithmetic, only integer, and handles some arrays. The PC was a
33MHz 486. And the second amazing thing is, that a IBM RS6000
(560)-Risc-machine needed 17 Min for the same code. I was the only
one on the machine. I thought it should be much faster. The MS C++
seems to make very fast, optimized code. The optimization was
configured to make fast code.
[Christoph Steinbeck (steinbeck@uni-bonn.de)]
7. How do you make a TEXTBOX read only? Or, how do I prevent the
user from changing the text in a TEXTBOX?
There's a lot of ideas on this one. You can grab the _KeyPress and
_KeyDown events and set them to zero. However, the best idea is to
use the Windows API SendMessage function to tell the control to
become read-only:
'After making the following declarations...
Global Const WM_USER = &H400
Global Const EM_SETREADONLY = (WM_USER + 31)
Declare Function SendMessage Lib "User" (ByVal hWnd As
|Integer ByVal wMsg As Integer, ByVal wParam As
|Integer, lParam As Any) As Long
'Then Try:
SendMessage(Text1.hWnd, EM_SETREADONLY, 1, 0)
[Pete Jones (pjones@csi.compuserve.com)]
This will still allow the user to copy *from* the text box. If you
need to disable this (why?), steal the Ctrl-C in the _KeyPress
event.
8. How can I create a VBX?
VBXs (Visual Basic eXtensions) are practically always written is C
(Borland C++, but mainly MS VC++). You should refer to the
_Control Development Guide_ (in VB Professional Features Vol. I)
and any relevant documentation for your compiler. Followup
questions should normally be directed to comp.os.ms-
windows.programmer.* or comp.lang.c*.
There are some example VBX's with C code supplied with VB3 Pro.
You'll find them under the directory [VB]\CDK.
9. How do you change the system menu (on the Control-Menu Box)?
You can turn off the minimize and maximize menu options by
changing properties, but what if you need to remove the "close"
option?
'Make the following declares.
Declare Function GetSystemMenu Lib "User" (ByVal hWnd
|As Integer, ByVal bRevert As Integer) As Integer
Declare Function RemoveMenu Lib "User" (ByVal hMenu
|As Integer, ByVal nPosition As Integer, ByVal wFlags As
|Integer) As Integer
Global Const MF_BYPOSITION=&H400
'Use the following code to remove the "close" option.
SystemMenu% = GetSystemMenu (hWnd, 0)
Res% = RemoveMenu(SystemMenu%,6, MF_BYPOSITION)
'(also remove the separator line)
Res% = RemoveMenu(SystemMenu%,6, MF_BYPOSITION)
Adding menu items to the control menu is more complicated, since
you need to respond to the events triggered when the user selects
the new options. The newest Message Blaster (msgblast.vbx, see
details in beginning of FAQ about how to get files) contains
example code.
10. How do I play MID, WAV or other multimedia files?
Use the MSMCI.VBX, provided with VB/Win Pro 3.0. You can also
declare and call the MM-functions manually:
Declare Function mciExecute Lib "MMSystem"
|(ByVal FileName as String) As Integer
Sub Form1_Click ()
iResult = mciExecute("Play c:\windows\mkmyday.wav")
End Sub
Also:
Playing a WAV file is covered in the VB Tips help file (there is a
Windows call that is for this specificially; see below). The
routine won't play MIDI files or other sound formats, however.
Declare Function sndPlaySound Lib "MMSYSTEM.DLL"
|(ByVal WavFile$, ByVal Flags%) As Integer
Global Const SND_SYNC = &H0
Global Const SND_ASYNC = &H1
Global Const SND_NODEFAULT = &H2
Global Const SND_LOOP = &H8
Global Const SND_NOSTOP = &H10
Global Const SND_USUAL = SND_ASYNC And SND_NODEFAULT
[John McGuire (jmcguire@jax.jaxnet.com)]
11. How can I call a 'hidden' DOS program from VB?
If you run a DOS program minimized using the SHELL command, it
will never complete. This is because DOS tasks by default are NOT
setup to run in the background. The easiest way to get around this
is to make a PIF file for the program you need to run with the
"Background" option checked. Then SHELL to the PIF file to run the
DOS program and it will return control to your VB application when
it terminates.
Tip: If you edit or replace the _DEFAULT.PIF file in the Windows
directory to allow execution in background, this will apply to all
DOS boxes that is not run with it's own .pif!
12. How do I do drag & drop between applications?
MSGBLAST.ZIP (the famous Message Blaster by Ed Staffin and Kyle
Marsh) available on Cica and mirrors tell you *everything* you
want to know about this and other advanced stuff. This is now
(inexpensive) shareware, but the older freeware version is still
supposed to be available. Get the file mentined above for more
info.
Short glossary for the confused ones :-)
Drag & Drop Client: the form you drop objects to/on
Drag & Drop Server: the form you drag object(s) from
13. How do I use GetPrivateProfileString to read from INI files?
There's a good example of accessing *.INI files in the Knowledge
Base, but here's the basic idea:
'You declare these API function as usual:
Declare Function GetPrivateProfileString Lib "Kernel"
|(ByVal lpApplicationName As String, ByVal lpKeyName
|As Any, ByVal lpDefault As String, ByVal
|lpReturnedString As String, ByVal nSize As Integer,
|ByVal lpFileName As String) As Integer
'Then in your code you do like below:
strIniFile = "WIN.INI"
strSection = "MyProgram"
strKey = "Language"
strDefault = "English"
iLength = 70
strReturn = String$(iLength, " ") 'Pad the string first!
iResult = GetPrivateProfileString(strSection, strKey,
|strDefault, strReturn, iLength, strIniFile)
WARNING: Be aware that there was an ERROR in the Windows 3.1 API
documentation that came with VB. Here's the scoop:
Knowledge Base article Q110826 (DOCERR: GetPrivateProfileString
Declaration Incorrect in API) corrects a documentation error for
the GetPrivateProfileString function call as described in the
Windows version 3.1 API Reference help file that shipped with
Microsoft Visual Basic version 3.0 for Windows. The CORRECT
declaration is as follows:
Declare Function GetPrivateProfileString Lib "Kernel"
|(ByVal lpApplicationName As String, ByVal lpKeyName
|As Any, ByVal lpDefault As String, ByVal
|lpReturnedString As String, ByVal nSize As Integer,
|ByVal lpFileName As String) As Integer
Note that the "ByVal" keyword was omitted from the second
parameter in the online reference. This means that the function is
passing the second parameter (lpKeyName) by reference. It needs to
be passed by value.
The most common problem that occurs when using the incorrect
declaration is that when the function is called, it returns a copy
of "lpdefault" in the "lpReturnedString" parameter instead of the
actual value referenced by KeyName.
OOPS: As P. Wierenga (pwiereng@sol.UVic.CA) told me, the same doc
error applies to Writeblablabla:
DOCERR: WriteProfileString Declaration Incorrect in API Article
ID: Q115328
The correct declaration is as follows:
Declare Function WritePrivateProfileString Lib "Kernel"
(ByVal lpApplicationName As
String,
ByVal lpKeyName As Any,
ByVal lpString As Any,
ByVal lplFileName As String) As
Integer
(all on one line of course!)
14. How do I implement Undo?
For most controls, you will have to keep track of changes
yourself. There's no magic involved, just some coding. However, if
you use the standard Text box or Combo box, Windows provides a
"free" undo function for you!
'Do the following declares:
Declare Function SendMessage Lib "User" (ByVal hWnd As
|Integer, ByVal wMsg As Integer, ByVal wParam As
|Integer, lParam As Any) As Long
Global Const WM_USER = &h400
Global Const EM_UNDO = WM_USER + 23
'And in your Undo Sub do the following:
UndoResult = SendMessage(myControl.hWnd, EM_UNDO, 0, 0)
'UndoResult = -1 indicates an error.
15. How do I create a window with a small title bar as in a floating
toolbar?
Download the MSGBLAST VBX from ftp.microsoft.com (filename
msgblast.zip) or (better) from ftp.cica.indiana.edu or mirrors.
The example files provide an example of a form with a small title.
When you see it, you'll understand why I haven't include a full
explanation here!
16. What is Pseudocode?
VB/Win does not generate machine code like most compilers do.
Instead it creates what is called pseudocode (a real misnomer,
IMO). A good explanation is given below:
A bit of history: the original P-code was an instruction set for a
"virtual Pascal" machine. This came with a portable Pascal
compiler written at ETH in Zuerich. The portable compiler produced
instructions for this phony machine which had an instruction set
ideally suited to the stack and heap management of Pascal. To
executed portable Pascal programs, you had two choices: either
write an interpreter for P-code, or translate the small set of P-
code instructions (there were about 80) into assembler; assemble
it; and run it at native speed. Thus "P-code" originally stood
for "Portable" or "Pascal" code. The broader meaning, "pseudo-
code" came later. P-code was widely popularized by the UCSD Pascal
system, a small workstation that was implemented entirely in Pcode
and interpreted. It was sold for some years, and one company even
re-did the microcode for a PDP-11 microchip to interpret P-code.
The original Borland Turbo Pascal had obvious similarities to the
UCSD system although it was not interpreted. The dialect was
virtually identical. Today P-code is used extensively in
Microsoft apps, for two reasons. First, it is much more compact
than native code; so the apps are smaller. Second, having an
interpreter at the core of an app makes it much easier to
customize and extend. That is why VB is becoming the heart of the
MS major apps. It is simply not true that P-code apps run much
slower than native apps. The slowdown is determined by the
granularity of the interpreted routines. If every little thing is
an interpreted op, the slowdown might be as much as 3-to-1 for the
80x86 architecture, or about 2-to-1 for the Motorola 68000 family
(which is better suited to writing interpreters). But in
practice, modern P-code systems have large-scale instructions,
each of which is executed by a big compiled subroutine. These subs
run at native speed, so the overhead of the interpreter is
occasional at worst.
[Roger E. Ison (r_ison@csn.org)]
It is also possible that since the code may not need recompilation
to run on other platforms *if* the run-time interpreter is first
ported, VB applications can become very portable. This depends on
Microsoft's long-term plans.
A note on the word "pseudocode": I wrote above that it is a
misnomer, and I stand on that. Pseudocode is *really* the pascal-
like (mostly) explanation of an algorithm that is intended for
human readers, not computers. But since somehow the term
pseudocode stuck to the psaudo-machine-code created by VB the word
is used here.
17. Does VB support pointers to functions?
No, it does not.
[George Tatge (gat@csn.org)]
18. How do I program the Novell NetWare API from VB?
Tom Tregilgas (Tom.Tregilgas@InfoB.unisg.ch) had a lot of
information on this one. Normally I leave it to the other FAQ
parts to list books & how-to-get-info's, but since this topic is
very specific and more NetWare than VB I include all the stuff
here for your convenience:
If you are interested in seeing how Visual Basic can be used for
NetWare programming, obtain the following files from your friendly
neighboorhood Novell FTP Mirror site.
Mirror sites are (according to ftp.novell.com):
Novell Germany ftp.novell.de
Netherlands ftp.rug.nl
United Kingdom ftp.salford.ac.uk
Logan, Utah netlab2.usu.edu
New Zealand tui.lincoln.ac.nz
Tuscaloosa, Alabama risc.ua.edu
Ottowa, Ontario, CA novell.nrc.ca
Boston, Mass bnug.proteon.com
novlib\11\nivb.zip Netware Interface for Visual Basic
novlib\11\nwtest.zip NetWare Test for Visual Basic
There are also two Novell App Notes on the subject of using
NetWare with Visual Basic (although this is _NOT_ supported by
Novell...) which are:
October 92 Interfacing Visual Basic for Windows and NetWare
July 93 A NetWare Interface for Visual Basic
The AppNotes can be obtained by contacting the Novell Research
Order Desk, FAX: +1 303 294-0903, Voice 800 377-4136, +1 303 297-
2725. Address as follows:
Novell Research Order Desk
1601 Park Avenue West
Denver, CO 80216-5199
AppNotes are $95/year ($135 outside US)
Here are a few books which might help you out to figure the calls
out:
Windows Development on NetWare Systems, Lori Gauthier and Sue
Whitehead (c) 1994, Windcrest, Blue Ridge Summit, PA 17294-0850
(McGraw-Hill) $34.95 Comes with disk This book also tells you how
to "upgrade" to the currently supported SDK calls
NetWare System Interface Technical Overview, Novell (c) 1990,1989
(Addison-Wesley), $32.95 (describes Novell's C Network Compiler
API's)
Visual Basic Programmer's Guide to the Windows API, Daniel
Appleman Ziff-Davis Press, 5903 Christie Ave, Emeryville, CA
94608, $34.95 Comes with disk
It should be mentioned that the APIs included with the NIVB are
_not_ current, and for this purpose, you should get the Novell SDK
kit. Also, Novell will not support NIVB, but you can sometimes get
some helpfrom Compu$erve, or from others on the Infobahn <g>
Good luck!
p.s. It behooves you to become a member in the PDP (Professional
Developer's Program) since you get the AppNotes (& Bullets!)
for...free.
p.p.s. Novell does NOT support the NIVB...
p.p.p.s. Also, no docs come with it. You'll probably need the
Client C SDK kit to be able to really _use_ the code.
p.p.p.p.s. To make things even better, the calls in NIVB are
fairly old, and not of the Client C SDK kit variety. However,
there _are_ books which could help you out, e.g. "NetWare System
Interface Technical Overview", by Novell. ISBN:0-201-57027-0,
published by Addison-Wesley Publishing co, $32.95 US, $42.95 in
Canada.
Update:
AppNotes are dead, however, Develper Notes live on. There is one
article about NetWare programming with Visual Basic here:
July/Aug 94 NetWare Programming in Visual Basic:
Using Apiary's NetWare Client SDK for Visual Basic
19. Visual Basic 4 news [**]
Here is the news we have observed (and which was a guess in
previous versions of this FAQ)
a. Two versions: 32-bit and 16-bit
Like Visual C++ 1.5, VB 4 comes with compilers for the 16-bit API from
Windows 3.1 as well as a real 32-bit compiler (or pseudocompiler) for
Windows 95 (and NT) bundled together.
b. New features inherited from VBA
1) VB 4.0 is really VB Applications Edition 2.0
2) Line continuation character " _" (space+underscore)
3) WITH statement, known from Pascal, to save typing and make code
cleaner. An example:
With Form1
With Text1
Bold = true
FontName = "New Times Roman"
End With
End With
4) FOR EACH .. NEXT statement allows you to make changes to a group
of objects at once better than FOR..NEXT. Syntax:
For Each element In group
[statements]
[Exit For]
[statements]
Next [element]
5) OPTIONAL statement allows you to leave some Variant parameteres
undefined when calling a user-defined sub or function. Also an ARRAY
function that returns an array form a list supplied as parametres, and
a special optional ParamArray optional parameter of Variants.
6) Boolean data type. Coded as 16-bit (2-byte), but can only have
TRUE or FALSE value.
7) Byte data type (8-bit). Can have values from 0 to 255.
8) FUNCTION can be of user-defined type.
9) OLE Automation allows detailed control over objects taken from
ie. Excel or Word.
10) Reusable Objects and Collections, called Classes
11) Property Procedures allows you to add custom properties to form
and some other modules.
12) New enhanced development environment, which includes an object
browser and allows add-ins. Pro edition also allows creation of your
own add-ins. (For some strange reason, the 32-bit version of this does
not use Win95 file dialog boxes!)
13) Conditional compilation: allows one source for 32- and 16-bit
versions.
14) Data bound DBList, DBCombo, and DBGrid controls! VB 4 uses Jet
2.5 engine.
c. VBX is dead. Long live OCX!
You may not feel for celebrating this either, but the 32 bit VB 4 will
not support the old 16-bit VBX'es. The 16-bit version of VB 4 will
support them for backwards compatibility, but be aware that OLE 2 and
OCX is the way of the future, at least if Microsoft gets it as they
want.
20. How do you change the icon and otherwise manipulate the DOS box?
Enclosed is the results of my digging around to enable me to
change the icon
of a DOS box launched with the SHELL function. It illustrates most
aspects
of dealing with DOS boxes.
Example of launching PIF file minimized and running it in the
background (Needs Execute Background box checked in PIF file), and
assigning the PIF file a new Icon rather than the default DOS Box
Icon.
(Note: it seems this method changes the icon of ALL the active DOS
boxes)
Code follows:
x-----------------------------------------------------------------
----x
Option Explicit
Global Const SWP_NOSIZE = 1
Global Const SWP_NOMOVE = 2
Global Const SWP_NOACTIVATE = &H10
Global Const SWP_SHOWWINDOW = &H40
Global Const SWP_HIDEWINDOW = &H80
Global Const SWP_FLAGS = SWP_NOMOVE Or SWP_NOSIZE Or
SWP_NOACTIVATE
Global Const SWP_SHOW = SWP_SHOWWINDOW Or SWP_FLAGS
Global Const SWP_HIDE = SWP_HIDEWINDOW Or SWP_FLAGS
Global Const HWND_BOTTOM = 1
Global Const GCW_HICON = (-14)
Global Const GCW_HMODULE = (-16)
Declare Function GetModuleUsage Lib "Kernel" (ByVal hWnd%) As
Integer
Declare Function ExtractIcon Lib "Shell" (ByVal hInst%, ByVal
lpExeName$,
|ByVal hIcon%) As Integer
Declare Function DestroyIcon Lib "User" (ByVal hIcon%) As Integer
Declare Function FindWindow Lib "User" (ByVal lpClassName As Any,
ByVal
|lpCaption As Any) as Integer
Declare Function SetWindowPos Lib "User" (ByVal h%, ByVal hb%,
ByVal X%,
|ByVal y%, ByVal cx%, ByVal cy%, ByVal F%) as Integer
Declare Function GetClassWord Lib "User" (ByVal hWnd%, ByVal
nIndex%)
|As Integer
Declare Function SetClassWord Lib "User" (ByVal hWnd%, ByVal
nIndex%,
|ByVal wNewWord%) As Integer
Sub LaunchPif(PifFile as String, IconName as String)
Dim Res As Integer 'Return value from API call
Dim MyInst As Integer 'Instance handle for this app
Dim PifIcon As Integer 'Pif Icon Resource name
Dim OldIcon as Integer 'Original Pif Icon resource (default =
0)
Dim PifhWnd As Integer 'Dos Box Window handle
'Launch PIF file
PifInst = Shell(PifFile, 6)
'Get Instance handle for main MDI Window (assumed to be
frmMDI)
MyInst = GetClassWord((frmMDI.hWnd), GCW_HMODULE)
'Create new Icon resouce by loading Icon from disk file
'Check Icon file exists
If Dir$(IconName) <> "" Then
'Make sure string is null terminated
IconName = IconName & Chr$(0)
'Create Icon resource in this window
PifIcon = ExtractIcon(MyInst, IconName, 0)
Else
PifIcon = 0
End If
'Reset Default Icon on DOS Box to PifIcon
'Check PIF file still running and Icon resource created
If GetModuleUsage(PifInst) <> 0 and PifIcon > 0 Then
'Get Pif Window handle
PifhWnd = FindWindow(0&, "Window name in PIF file")
'Set Icon handle to PifIcon resource
OldIcon = SetClassWord(PifhWnd, GCW_HICON, PifIcon)
'Hide and show window to get a redraw of the Icon
Res = SetWindowPos(PifhWnd, HWND_BOTTOM, 0, 0, 0, 0,
SWP_HIDE)
Res = SetWindowPos(PifhWnd, HWND_BOTTOM, 0, 0, 0, 0,
SWP_SHOW)
End If
'Wait for PIF file to complete
Do While GetModuleUsage(PifInst) <> 0
DoEvents
Loop
If PifIcon > 0 then
'Reset Icon to original
Res = SetClassWord(PifhWnd, GCW_HICON, OldIcon)
'Tidy up by removing PIF Icon resource
Res = DestroyIcon(PifIcon)
Endif
End Sub
x-----------------------------------------------------------------
----x
[Dr David Baird (BairdD@AgResearch.CRI.NZ)]
21. How do I make the mouse cursor invisible/visible?
Use the API call ShowCursor(False) or ShowCursor(True). Just be
aware that the Windows cursor is a shared object, so if your
process hides it then it must also redisplay it as well. Also the
function is not truly "True" or "False" in nature - it is LIFO, so
that if your process has for some reason set it "False" multiple
times then you must set it "True" the same number of times in
order to re-display the cursor. Hard to explain but play with it -
you'll see what I mean...
[Galen Raben (galenr@hpgrla.gr.hp.com)]
22. How do I create controls dynamically (at run-time)?
Search of VBKB_FT on "control* near array*" finds a number of
articles, including Article ID: Q79029 "Creating Nested Control
Arrays in Visual Basic" This is THE article to read to understand
control arrays (plus a number of other neat concepts). In
particular, look at the procedure "loadall_click".
The key is that you need to create the first instance of
your_control (ie. your_control(0)) at design time.
[Ayn Shipley (ashipley@hookup.net)]
23. How do I set the Windows wallpaper at runtime?
I'm surprised this isn't in the FAQ yet. [ED: now it is!] You need
the SystemParametersInfo API function and the SPI_SETDESKWALLPAPER
constant.
For this you will need the following constants and function
declaration...
Const SPI_SETDESKWALLPAPER = 20
Const SPIF_SENDWININICHANGE = &H2
Const SPIF_UPDATEINIFILE = &H1
Declare Function SystemParametersInfo Lib "User" (ByVal uAction As
|Integer, ByVal uParam As Integer, lpvParam As Any, ByVal
fuWinIni As
|Integer) As Integer
'You then call the function as follows...
Result% = SystemParametersInfo(SPI_SETDESKWALLPAPER, 0, ByVal
BMPFile$,
|SPIFlags%)
'... where SPIFlags% is 0 if the change is not to be made
permanent, or
'(SPIF_UPDATEINIFILE Or SPIF_SENDWININICHANGE) if it is to be
carried across
'into future Windows sessions.
NOTE: Please be certain to include the ByVal keyword before the
bitmap
filename, as this argument is declared as Any, NOT as ByVal
String.
[Luke Webber(webber@werple.apana.org.au)]
24. How do I call help files from a VB program? [**]
There are 2 ways you can display help files:
1) In code
a) Using the common dialog control
b) Making a winhelp api call
(see below for examples)
2) Pressing F1 when App.HelpFile is set to your
help file.
Note - if a control's HelpContextID property is
set to the context id of a help topic, that topic
will be displayed if the control has focus and the
user presses F1, otherwise the contents is displayed.
(see Mapping Context-Sensitive Topics, Chapter 6 pg. 117
of the Professional Features Book 1 for information on
setting the context ids for your help file. Many help
authoring tools will generate the context ids for you.)
- Include constant.txt in your project
- Set App.HelpFile = "c:\yourfile.hlp"
- Declare the following function in a .bas module
(make sure it is all on one line):
'Function for display windows help files
Declare Function WinHelp Lib "User" (ByVal hWnd As Integer,
ByVal lpHelpFile As String, ByVal wCommand As Integer,
dwData As Any) As Integer
COMMON DIALOG:
---------------
Note - The HelpContext property can only be assigned
an integer. The equivalent WinHelp Api call can use a long.
In this example the context id is 1000
jump to a context id within help file.
CMDialog1.HelpFile = "c:\yourfile.hlp"
CMDialog1.HelpCommand = HELP_CONTEXT
CMDialog1.HelpContext = 1000
CMDialog1.Action = 6
bring up contents
CMDialog1.HelpFile = "c:\yourfile.hlp"
CMDialog1.HelpCommand = HELP_CONTENTS
CMDialog1.Action = 6
bring up search window
CMDialog1.HelpFile = "c:\yourfile.hlp"
CMDialog1.HelpCommand = HELP_PARTIALKEY
CMDialog1.HelpKey = ""
CMDialog1.Action = 6
quit help
CMDialog1.HelpFile = "c:\yourfile.hlp"
CMDialog1.HelpCommand = HELP_QUIT
CMDialog1.HelpContext = 0
CMDialog1.Action = 6
WINHELP API:
-----------------
In the following examples iRetCde is declared as an integer.
Jump to context id (e.x., context id is 1000)
iRetCde = WinHelp(Me.hWnd, "c:\yourfile.hlp", HELP_CONTEXT,
ByVal CLng(1000))
bring up contents
iRetCde = WinHelp(Me.hWnd, "c:\yourfile.hlp", HELP_CONTENTS,
CLng(0))
bring up search window
iRetCde = WinHelp(Me.hWnd, "c:\yourfile.hlp", HELP_PARTIALKEY,
ByVal "")
quit help
iRetCde = WinHelp(Me.hWnd, "c:\yourfile.hlp", HELP_QUIT,
CLng(0))
[Blake Miller (bemiller@amoco.com)]
E. CALLING THE WINDOWS API AND DLLs IN GENERAL
1. What is the Windows API?
The Windows API (Application Program Interface) is a collection of
Dynamic-Link Libraries (DLLs) that do most of the common things in
Windows. Calls to the Windows API gives you access to routines
that do things like drawing menu bars, manipulating bitmaps,
playing sound files, and pretty much every other function of
Windows.
2. How do I call a DLL?
Basically, you declare a DLL procedure which you can call in your
VB program which in turn passes data to and/or retrieves data from
the DLL. You should read the section of the VB manual that talks
about calling DLLs ("Chapter 24 Calling Procedures in DLLs" in
the VB 3.0 Programmer's Guide). This chapter covers the basics of
using the Windows API DLLs and calling DLLs in general. Beyond
that you may want to find a good book on this subject since it is
too large to cover here (see the Book Listing in the Appendix of
the General FAQ - Part 1). Don't be too intimidated! Using DLLs
(especially many of the Windows API functions) is quite easy, once
you learn how to call them. In fact, many of the newer DLLs
include VB-compatible modules!
3. What about DLL calls that require callbacks?
VB does not support callbacks, but various extensions can help.
Dan Appleman's "Visual Basic Programmer's Guide to the Windows
API" comes with a floppy disk which code samples and tools. It
also includes a VBX which supports the callbacks which many API
calls require. Dan is also founder and president of Desaware which
sells more extensive tools, including SpyWorks, for VB developers.
[Walter Hill (whill@netcom.com)]
4. Tips for calling DLLs (such as the Windows API)
a. Using the BYVAL keyword is critical. Using it when you're
supposed to call by reference and (more common) not using it when you
are to give a value to the external function are the single most
common mistakes. Wrong calling convention can often result in a
General Protection Fault (GPF) or, even worse, corruption of another
applications' data.
b. Check return and parameter types. For return types, a C function
declared as "void" means you use a Sub not a Function.
c. Initialize strings by padding it to the necessary length! If you
pass a string that is too short to the API it will happily write past
the end of the string and possibly corrupt data.
d. Use Option Explicit. A typing error that results in a bug in the
VB source will occasionally cause a GPF when you call external code.
e. It's a jungle out there! Check parameter values as there is no
type checking outside VB. If you make a mistake, you'll often get a
GPF.
f. Save before you run! You may even need to restart Windows after a
GPF, since DLL's often aren't unloaded properly. As a second option
you can check out WPS (Windows Process Status) which is distributed
with VB/Pro and placed in the CDK directory. This utility allows you
to kick out any module (EXE, DLL) from memory (shooting yourself in
the foot if you want to. WPS is a nice way to find out what DLLs are
actually used, but save your work first!).
F. VISUAL BASIC AND DATABASES
1. Why can't I use an index with my VB accessed database?
There is a mistake in the docs which says you can set the active
index for a recordset. You can't. The data control uses the
primary key for tables and physical order (I think) for dynasets.
[Nic Gibson (nic@skin.demon.co.uk)]
NOTE: You can of course set the indexes yourself using code in
VB/Pro (Table objects), but Data Control's can't. Sorry for the
problems this possible misunderstanding caused!
Thanks to John McGuire (jmcguire@jax.jaxnet.com) for clarifying
this.
2. "Can't find installable ISAM" or Why does my compiled VB database
app generate an error when it ran just fine in the design environment?
You can thank Microsoft for documenting this topic so poorly. When
you compile your VB database application, you must also have an
INI file for it which provides the correct pointers to the
appropriate database drivers. Therefore, if your application is
named "INVOICE.EXE", you will need to have a properly configured
"INVOICE.INI" file in your Windows directory. The file,
EXTERNAL.TXT, that came with VB should explain all about it.
3. Is the Access Engine and Visual Basic Pro good enough for
database work?
That, of course, depends. Generally the answer is "yes", but you
may need some third-party add-on products.
These are the major weaknesses of VBPro's database functions:
a. Limited data controls: No add, delete or search button; no bound
list box or masked edit control and - the worst - no bound grid!
b. No run-time query builder ("how good is your user in SQL?") or
report builder.
c. No direct advanced control of the Access 1.1 (or 2) Database
Engine (ie. security, optimization, etc).
d. SQL us SLOW. Handcoding is much faster (but harder to code)
The good news is that lots of companies are willing to sell you
products which address one or more of the above weaknesses.
Also, if you build a database application with advanced database
relations, it can be a good idea to build the database itself with
Access and the front-end with VB.
4. How do you avoid the "Invalid use of null" error when reading
null values from a database?
If you try to retrieve a null value (empty field) from a database,
you will get the error: "Invalid use of Null". Here is one way to
get around this problem:
I've worked around this problem with the following code:
TextBox.Text = MyTest.Fields("TestFld") & ""
This code converts the Null-Value into an empty string.
[Ralf Metzing (rmm@dragon.stgt.sub.org)]
5. What is "NULL"?
Contrary to popular belief, Null is not nothing. It's even less
than nothing. 8^)
The VB documentation describes all the horrors of misunderstanding
the infamous NULL. Since people don't read the documentation, we
feel like informing that
If ThisVarIsNull = NULL then DoSomething
will *always* fail, and the DoSomething can't possibly be
executed. You *must* use IsNull(ThisVarIsNull) which will return
True if the var is Null (phew!).
If you want to find out why someone came to think of this strange
value, read some relational database theory.
6. How can I access a record by record number?
Use a counter or index field - or even better, a Bookmark property
- for this.
It is *impossible* to ask a relational database system to give you
ie. "field number 3 in record number 10" since by definition a
relational database does not have row or column numbers. Databases
allowing direct access like that is not even remotely relational.
Access (and therefore, VB) is about as close to a real relational
database system as you can get.
7. How about Access 2.0 compatibility?
You need the compatibility layer availability. The file COMLYR.EXE
is in the MSBASIC library on Compuserve. This file provides all
the items necessary for compatibility between VB 3.0 and Access
2.0.
[Fred Griffin (72321.3230@compuserve.com)]
For unknown reasons you can't install the compatibility layer
without Acess 2.0 being installed, even if you just want to open a
database from VB that was created by someone else.
[Kent Boortz <boortz@sics.se>]
The file COMLYR.EXE can be downloaded from ftp.microsoft.com. It
is located in the directory /softlib/mslfiles. (NOTE: A "DIR" in
this directory is rarely a wise course of action. There is an
enormous amount of files im /mslfiles.)
8. Tips for VB database programming:
a. Use Access and QBE. Once it's "working" (even if the parameters
are hardcoded), then open up View.SQL and copy the stuff from the SQL
window into your VB code. If you need to insert VB variables, try
testing this under Access by using parameters instead. They're then
nice & easy to spot when it comes to converting into VB - I always
call my parameters "PR_xxxx", so I can just search my VB code for this
to find any instances that I've missed.
b. It never works first time. So put an error handler into your VB
code that copies the contents of SQLStr onto the clipboard, should the
query fail. Now it's quick & easy to switch back to Access, find a
scratch query and paste the erroneous SQL into that. It's *much*
easier to debug a SQL query in Access, after the variables have been
merged in, than it is to do it blind from VB.
c. Use carriage returns to break up your SQL. One before each
reserved word is sensible. They're not significant in SQL. I assume
you're not stupid enough to put them in the middle of field names -
unfortunately Debug.Print is!
d. When merging in the contents of a variable (building a SQL query
in a VB string), it should *always* be surrounded by an ampersand and
3 double quotes, or an ampersand and 2 mixed quotes, depending on your
local conventions:
SQLStr = SQLStr & "WHERE Username <= """ & Username$ """ "
or
SQLStr = SQLStr & "WHERE Username <= '" & Username$ "' "
e. If you're using dates, then it will *always* be one quote, a hash
and an ampersand:
SQLStr = SQLStr & "WHERE Start_Date <= #" &
|Format$(CutOffDate,"Long Date") & "# "
f. Another tip with dates is to format them with the long date
format, not the short date. This is then safe against the
transatlantic reversal of month & day position.
g. If you're merging in a field/table name, enclose it in square
brackets. That way the SQL will still be valid if the variable
contains spaces:
SQLStr = "SELECT * FROM [" & TableName$ "] ;"
When building SQL strings in VB, then you'll often do this on several
lines, concatenating SQLStr with the new string. If you leave a space
at the end of every string, then you can guarantee you won't have
problems with the text from successive lines running into each other.
h. If you're using Access 1, you'll keep running into the 1024
character limit on the length of a SQL string. Keep the table & field
names short, especially if many JOINs are concerned. Using underscores
in names is shorter than spaces, as you don't need the extra 2
characters for the square brackets around them. If your SQL is
slightly too long, then you'll probably see a "Missing semicolon"
error, even though the semicolon is obviously there (To you, anyway!).
i. Making a QueryDef is a complicated process that is often slower
than executing the query ! Don't mess with the .SQL property, as that
is equally slow (Access needs to do a lot of work to turn SQL into its
internal query format). Two ways around this: Use ready-built queries,
written with Access. If you need to merge in values from variables,
then use a query with parameters. Setting parameter values is quick to
execute.
j. If you really need to build SQL on the fly -- you need to build
an ad hoc query, or to supply table or field names (which can't be
done with query parameters), then try using:
database.Execute SQLStr
As this doesn't build a QueryDef, then it's quick.
[Tips a to j by Andy Dingley(dingbat@codesmth.demon.co.uk)]
k. Make sure all Tables, Dynasets, Snapshots, Databases, and other
data access objects are properly closed before ending the program. As
near as I can tell, the pointers to these objects are not destroyed if
your VB program doesn't Close them (including when a program crashes).
A Microsoft guy did say he can't find anything that confirms that they
close, but (of course) he wouldn't say for certain that they aren't
closed. Based on resources after serious crashes (that I couldn't walk
the program out of by hand), I don't think they're automatically
closed.
[John McGuire (jmcguire@jax.jaxnet.com)]
9. How come I get a "No Current Record" error when I use a a Data
Control on an empty table?
Well, this is a "feature" courtesy of Microsoft. KB article
Q106494 explains this in detail. Basically, the workaround is to
add an empty record to the table before the user can do anything
(or before you try to do any Moves on the Table).
[George Tatge (gat@csn.org)]
10. How can I speed up my VB database application?
KB article Q109830 gives some hints. Things you should do
include:
- Use Snapshots when possible.
- Use transactions whenever possible.
- Use Dynasets when possible.
- Use SQL action queries when possible.
[George Tatge (gat@csn.org)]
Major Weakness: SQL is SLOW! A hand-coded search (with indices) is
MUCH faster than an equivalent SQL call, especially with complex
search criteria. For example:
SELECT * FROM Table WHERE SSN = '555-33-1234' AND Posted #01-31-
95#
is a lot slower than:
Table.Index = "SSN"
Table.Seek "=", "555-33-1234"
If Not Table.NoMatch Then
While Not Table.EOF
If Table("SSN") "555-33-1234" Then
Table.MoveLast 'Forces an EOF
ElseIf Table("Posted") #01-31-95# Then
'Do something
End If
Table.MoveNext
Wend
End If
Granted, it is a LOT more code, but I ran a VERY similar query
that took THIRTY HOURS! The equivalent hand-written code took
ELEVEN MINUTES! That's 163 times faster! I think basically SQL
isn't very good at figuring out which indexes to use (I also think
I've read something to the effect that the newer version, 2.0 or
2.5, IS better at this).
[John McGuire (jmcguire@jax.jaxnet.com)]
11. How do I get a bitmap picture in a field in an Access database?
See p.466 of the Visual Basic (3.0) Programmer's Guide. It
contains a section called "Using Bound Picture Box and Image
Controls". Basically you have to bind the VB PictureBox to a field
in the Access DB, set the .Picture property in the PictureBox, and
then move to the next record or something. VB will then store your
picture in Access in a form in which it can be retrieved by VB in
the future.
If you store the pictures in Access directly (using Access), VB
won't be able to read them (using VB 3.0 and Access 1.1).
You can also store the picture's filename as a text field in the
database and use LoadPicture() to load that file into the VB
PictureBox.
[Tim Shea (shea@marcam.com)]
12. What is "Reserved Error -1209"?
You will get a Reserved Error [-1209] ("There is no message for
this error")
when your database is corrupted. Try opening the database using MS
Access;
if it's corrupted you should get the option to repair it.
[Joe Abley (joe_abley@originuk.demon.co.uk)]
You should also compact it, after repair. I recommend you add the
following to your File menu on your main form:
Case ...
RepairDatabase Curentdatabasename
Case ....
On Error resume next
Kill "temp.MDB"
Name curentdatabasename as "temp.mdb"
on error goto errcompact
compactdatabase "temp.mdb", Currentdatabasename
kill "temp.mbd"
exit sub
errcompact:
msgbox "compaction failed"
name "temp.mdb" as Currentdatabasename
Case ...
[Ayn Shipley (ashipley@hookup.net) , Kym Wilson]
13. "Cannot perform operation. illegal.." with Paradox 3.5 table(s)
Your Paradox table must have a primary key, or it will be read-
only no matter what you set its properties to.
[Ayn Shipley (ashipley@hookup.net)]
14. I'm getting error message "Reserved Error [-nnnn] ("There is no
message for this error")" from Jet Engine 2.0. Huh?
See the Knowledge Base article Q117900 "Reserved Error Numbers
Returned by
the Jet 2.0 Engine" for a complete list of the new error messages.
Extract:
"Jet_Error/Message_String
-1010 Invalid database ID.
-1016 Can't have more than 10 fields in an index.
-1029 Database engine hasn't been initialized.
-1030 Database engine has already been initialized.
-1034 Query support unavailable."
[Ayn Shipley (ashipley@hookup.net)]
15. Why do I get "object not an array" when I try reference the
fields of a global object variable which I have set to a table?
VB has a parser bug which makes it difficult to use database
objects declared in a module from within a form.
WORKAROUND: Just perform some _method_ on the table object
somewhere _before_ you try to reference fields. Say in a form-
based subroutine AAAA_IllBeFirst you have a Tbl.MoveFirst, which
is never even executed. Then VB suddenly realises what the object
is and all is forgiven.
Credit to Luke Webber and "Joe Foster of Borg".
[Ayn Shipley (ashipley@hookup.net)]
16. Steps for securing an Access 2.0 database [**]
What I started with:
A database that I wanted to make secure.
Access 2.0 installed on my hard drive.
No Access permissions or accounts ever played with under Access.
1) I ran MS Access Workgroup Administrator and created a new
SYSTEM.MDA and assigned a unique workgroup id.
2) Ran Access and created a new database, DB1.MDB.
3) Changed the password for the Admin user using Change Password
under
the Security menu. Changed the password from nothing to
"PASSWORD".
4) Clicked on Users under Security. Added a new user, "JOEUSER"
and made
it a member of the Admins and Users groups.
5) Closed Access, deleted the new database I had just created,
DB1.MDB,
and restarted Access. Logged in as the new user, "JOEUSER".
Created
a new database named DB1.MDB. Changed the password from
nothing to=7F
"PASSWORD".
6) From the File menu, clicked Add-ins and then Import Database.
Imported
my database, REAL.MDB, that I wanted to make secure.
7) Went to Permissions under the Security menu and turned off all
permissions for all Groups and all Users for the database, all
tables,
forms, macros, etc. The only permissions I left on was full
permissions
for all objects for the new user, "JOEUSER". After changing
the
permissions, I closed Access (note that the database I just
used was
DB1.MDB).
8) I made a backup of my database REAL.MDB and renamed DB1.MDB to
REAL.MDB.
9) Opened my VB code and added the line:
SetDefaultWorkspace "JOEUSER", "PASSWORD"
right before the line where I open the database.
10) Copied the SYSTEM.MDA from my C:\ACCESS directory to the
directory
where my VB code is. (Note, I do not have an INI file for my
program).
11) Ran my VB program and my database can be opened by my program
and nobody
else. The SYSTEM.MDA has to be delivered with my program
however.
See SetDefaultWorkspace and SetDataAccessOption in VB help for
more information on how to set up the data access paramaters in an
INI file. Make sure you add error handling for a missing or
messed up SYSTEM.MDA file.
I think this is a good basic way to prevent people from
looking/changing your database. Possible flaws are looking at a
dump of the .EXE file and finding the name and password used to
open the database (there are various workarounds for this) and
also running a program to look at parameters passed when opening
the database (don't know if this is possible and can't think of a
workaround if it is).
[Justin F. Smith (jsw117@psu.edu)]
G. DISTRIBUTING VISUAL BASIC APPLICATIONS
1. What are some tips for using Setup Wizard?
There were loads of bugs in the setup utilities supplied with VB3.
Be sure to get the newest version of SETUPKIT (usually called
SETUPK.EXE or -.ZIP). It is available from the sources listed in
the beginning of this document, and in the General FAQ.
Alternatively, if you have the older versions, you may have to
manually remove the line referring to OLE2UI.DLL in the file
SETUPWIZ.INI. See later in this document for dates of newest files
on ftp.microsoft.com.
Follow the instructions in SETUPK.TXT exactly. The files actually
belong in two separate directories. Not placing them correctly can
create strange and unusual side effects -- none of them good(!)
Set all involved EXE, DLL and VBX files to Read-Only so that the
setup program doesn't modify them.
[Charles F. Mulks (21667cfm@msu.edu)]
A *very* good tip. Actually, make all executables on your system
read-only. If not, you can get a sharing violation if you try to
run the same DOS executable twice at the same time.
Also, the source code for a SETUP program is *included* with VB3
Pro. It is quite trivial to tailor it to your specific needs.
The question remains: Is SetupWiz good? No! Good enough? Perhaps.
2. Are there restrictions on what I can distribute with my VB
program?
The documentation tells what parts of the Visual Basic kit you can
freely distribute: the VBX files, some DLL's and what the SetupKit
includes on your distribution diskettes. Reading software license
agreements may be more boring than asking the newsgroup, but is
nevertheless a good idea. 8^)
There have been some rumours on the newsgroup that you can't
redistribute programs written with VB freely. This is nonsense.
All applications created with VB can be redistributed freely
without royalties (as long as you don't distribute proprietary
external files).
The rumours probably originated when Microsoft announced that they
will not sell kits allowing third-party software to include the
Visual Basic for Applications (VBA) system.
3. What alternatives to setup wizard do I have?
Perhaps the best one is to simply modify the setup app which is
supplied with VB. Look in your VB directory for the setupkit\
setup1 directory. There you will find everything you need to do a
complete setup program. This sample setup is coded to install a
few sample app files and create a program group. You can comment
out those lines and change to your files and program mgr. group.
There are also a few global variables you will want to change.
All of this is contained in the comments in the code.
Using this, and the distribution information in the manual telling
you about which files to distribute with your app will make things
much easier than using the setup wizard (IMNSHO).
There are also several third party setup products available.
[George Tatge (gat@csn.org)]
4. Do I need to worry about users who have Progman replacements such
as Norton Desktop and PC Tools?
Earlier versions of those products and some others do not respond
properly to the DLL commands to create groups and items. More
recent versions do. All you can do in this case is to include
some information in your readme.txt file that instructs users of
those products to shut them down and start up program manager
before installing.
[George Tatge (gat@csn.org)]
5. Can I distribute my app without vbrunXXX.dll?
If you are sure that your users have it or can get it, you can
easily distribute your app without vbrunXXX.dll. Simply remove
the file from your distribution disk or zip file and and ALSO
remove it from the setup.lst file.
[George Tatge (gat@csn.org)]
6. Why won't my setup program install commdlg.dll et. al.?
There are a couple of DLLs that are almost always in use by
windows. Commdlg.dll is the most common example. When faced with
this problem, there is no easy way out. The full explanation is
several pages long and beyond the scope of this FAQ. The general
idea is as follows:
Your setup program will need to create a .BAT file to expand and
then copy these files. Then, it will need to shutdown Windows
(see ExitWindowsExec API call) and run the .BAT file. Then it
will need to restart windows and continue your setup program.
Your setup program should delete the temporary .BAT file that is
no longer needed.
[George Tatge (gat@csn.org)]
7. Where do I install VBXs and DLLs?
PLEASE- this is one place where everybody's life is much easier if
you will follow Microsoft's recommendations. All PUBLIC VBXs and
DLLs should be installed in the windows/system directory! A
"PUBLIC" DLL or VBX is any which can be purchased on the open
market. In other words, if another VB programmer might possibly
use the same VBX or DLL, install it in the
system directory.
If you have written private VBXs or DLLs that will never be used
by any program but yours, you can install them in the same
directory where you install your application files.
There are lots of good reasons for doing this, but it makes a
short novel to rehearse them all.
[George Tatge (gat@csn.org)]
H. MISCELLANEOUS TIPS AND INFORMATION
1. Multiple identifiers after the DIM statement can be confusing
Some programmers with background from Pascal can try the following
Dim iA, iB, iC as Integer
and think that all these 3 variables end up as Integer. In fact,
the first two end up as default data type, normally Variant.
Instead you should do
Dim iA as Integer
Dim iB as Integer
Dim iC as Integer
which takes up more space, but gives you room to comment your
variables (hint, hint); *or*
Dim iA%, iB%, iC%
which does the whole job.
2. "Clean up" your project before final EXE compilation.
When you are ready to compile your VB project into your 'finished'
EXE, be sure to save the project files, exit VB, restart Windows,
run VB, load your project and go straight to compiling. Otherwise,
your EXE may be larger in file size than necessary due to
'garbage' getting included in the EXE. For some reason, VB does
not fully clean up all of the previously used variables or objects
that you may have been playing with while developing your program
so these get included in your EXE even though they aren't used.
Other VB users have even advocated saving all the project files as
ASCII, then loading the ASCII files before compiling to further
"clean up" the resulting EXE file.
3. Multiple END statements can be dangerous; or, The program that
refused to terminate.
Suggestion: put the END statement used to exit your program *only*
in the Form_Unload event of the main form. Whenever you want to
end the program, just tell the main form to unload.
Some have reported that after their program have (supposedly)
terminated, it still appears in the task list. This can happen if
you only hide secondary forms and forget to unload them when you
end/unload the main form.
Also note that the Stop-button on the button-bar of the integrated
development environment doesn't really unload anything. It *nukes*
the program, which generally is a good idea since it could be a
bug in it that caused it to be stuck in an eternal loop or
something.
4. What are the latest versions of the various files used by VB?
Date File to download Updates files Description
3/7/94 BTR110.EXE BTRV110.DLL Btrieve IISAM Driver
3/7/94 DATAINDX.EXE DATAINDX.DOC "Data Access Guide"
Index
3/7/94 GENERIC.EXE \VB\CDK\GENERIC Sample custom control
source
3/7/94 VBGRID.EXE GRID.VBX Grid control
3/7/94 VBHC505.EXE HC.EXE, HCP.EXE WinHelp compiler
3/7/94 MSAJT.EXE MSAJT110.DLL Access Database Engine
3/8/94 MSCOMM.EXE MSCOMM.VBX Serial
Communications\control
3/7/94 ORA110.EXE ORACLE.TXT Updated ORACLE.TXT file
6/27/94 SETUPK.EXE SETUP.EXE Setup Toolkit
3/7/94 VBRUN300.EXE VBRUN300.DLL Visual Basic Runtime
Library
3/7/94 XBS110.EXE XBS110.DLL XBase IISAM Driver
There is an article in the Microsoft Knowledge Base that points to
each of these files and provides more detailed information about
the update. To find these articles, query the Microsoft Knowledge
Base using the file