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From: [email protected] (Kris Nosack)
Subject: FAQ: comp.lang.basic.visual VB/Win Frequently Asked Questions
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VISUAL BASIC FOR WINDOWS (VB/Win)
Frequently asked Questions & Answers
Section IX - B
TABLE OF CONTENTS:
A. PREFACE
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. Are there any examples of commercial applications built
using Visual Basic?
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?
23. Why doesn't "my string" & Chr$(13) do what I want?
24. How do I prevent multiple instances of my program?
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?
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. Some Visual Basic 4 rumours
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. 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 pitmap picture in a field in an Access
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
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 newsgroup. 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.
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 in the directory "pub/usenet/comp.lang.basic.visual".
You can also have the VB FAQs e-mailed to you by sending a message to
"[email protected]" with ONLY the text
send usenet/news.answers/visual-basic-faq/*
in the BODY of the message.
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. 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 ([email protected]), 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?
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 ([email protected]), Andy Dingley
([email protected]), and those I may have forgotten
(sorry).
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 currently at version 3.0
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
- 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're not alone. The organisation of this ftp site is *ugly*.
Here's a *very* useful map. It was valid as of 16 June 1994; I
have the impression they move things around just for fun!:
|- [ADVSYS]
| |- [LANMAN]
| |- [MAIL]
| |- [MSCLIENT]
| |- [ODBC]
| |- [SNASRVR]
| |- [SQLSRVR]
| |- [WINNT]
| |- [WINSOCK]
|
|- [DESKAPPS]
| |- [ACCESS]
| |- [DRAW]
| |- [EXCEL]
| |- [FOX]
| |- [GAMES]
| |- [GRAPH]
| |- [MMAPPS]
| |- [MONEY]
| |- [MSPUB]
| |- [OFFICE]
| |- [POWERPT]
| |- [PROJECT]
| |- [VIDEO]
| |- [WORD]
| |- [WORDART]
| |- [WORKS]
|
|- [DEVELOPER]
| |
| |- [DEVTOOLS]
| | |- [DELTA]
| | |- [FOX]
| | |- [LANG] -----
| | |- [MAPI] |- [BASIC]
| | |- [TAPI] |- [CCPP]
| | |- [WIN32DDK] |- [FORTRAN]
| | |- [WIN32SDK] |- [MASM]
| | |- [WINSDK] |- [MFC]
| | |- [MSVC32]
| | |- [MSVCWIN]
| | |- [TEST]
| | |- [VB]
| | -----------------|-----------------------
| | | | |
| | [KB] [PUBLIC] [UNSUP-ED]
| | |- README.TXT (Note 1) |- INDEX.TXT (empty)
| | |- INDEX.TXT (Note 2) |- *.EXE (Note 3)
| | |- [Q* ]
| |
| |- [DRG] (Developer Relations Group)
| |
| |- [MSJ] (Source code from Systems Journal)
| |
| |- [MSDN] (Developers Network) (Note 4)
| |- [CD7] (some VB stuff, get index)
| |- [NEWUP] ('C' code for animation & pic edit control)
| (also WHATHLP.ZIP)
|
|- [MISC] (Internet Engineering Task Force docs)
|
|- [MSATWORK]
|
|- [MSFT] (For MS Investors)
|
|- [PEROPSYS]
| |- [MMEDIA]
| |- [MOUSE]
| |- [MSDOS]
| |- [WFW]
| |- [WIN3X]
| |- [WIN-NEWS]
|
|- [SOFTLIB]
|- SLLIST.TXT (files in [MSLFILES] 1200+ entries) (Note 5)
|- [MSLFILES] (Note 6)
Notes:
1: Read this to understand the Q* directory structure.
2: 1400+ entries.
3: DLL/VBX updates.
4: MSDN has been reorganised and many files have been renamed and
put in [CD7]. If you see MSDN-IDX.ZIP, it's the index for the
old file arrangement, ignore it. The index/abstracts viewer
(was msdn100.zip) is being updated by the author and should be
available from CICA and mirrors in a few days.
5: If you find 'duplicate' entries at the end of this file they
are a list of additions/updates.
6: Contains VBKB.EXE (VB_BUGS & VB_TIPS) 1.5Mb !
VBKB_FT.EXE (VB_BUGS & VB_TIPS *with text search*) 4.2Mb !!
Map with notes supplied by Richard Mason ([email protected])
Please mail him direct if you discover any significant inconsistencies
between this map and the real world.
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, as noted above!)
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
newsgroup, 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 ([email protected]).
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 at 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).
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 for more information.
There's a VISBAS-L mailing list for Visual Basic. You can
subscribe to this mailing list by sending an email to
[email protected]
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 every day on the list, and we're really fed up!)
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. There's recently been a major group
creation process. Those groups that may be of special interest
to VB programmers are marked with *:
comp.os.ms-windows.misc
comp.os.ms-windows.programmer.misc
comp.binaries.ms-windows
comp.os.ms-windows.advocacy
comp.os.ms-windows.announce
comp.os.ms-windows.apps
comp.os.ms-windows.nt.misc
comp.os.ms-windows.nt.setup
comp.os.ms-windows.programmer.tools *
comp.os.ms-windows.programmer.win32
comp.os.ms-windows.setup *
comp.os.ms-windows.programmer.winhelp *
comp.os.ms-windows.programmer.networks
comp.os.ms-windows.programmer.graphics
comp.os.ms-windows.programmer.controls *
The latest groups have been added to split the enormous traffic
on the *.misc groups down in managable chunks. However, the
second group (.programmer.misc) contains lots of interesting
info (mostly C related), if you have the time to read it all!
Also note comp.lang.pascal which is a very good newsgroup for
Pascal, including Borland Pascal and Turbo Pascal for Windows.
Please don't use this guide to find out where you should
crosspost VB questions. Check the charter for each group before
posting to it. If you are sure that your crosspost is
legitimate, please note the crossposting in the text.
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
[email protected] to Shirley Modric for subscription
info. Address is 280 Second Street, Suite 200, Los Altos, CA
94022-3603 USA (Note: for completeness other VB magazines
should be listed, and I would like to receive info on those!)
6. 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.
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.
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 until it is dismissed. When showing a modal
form, the program pauses at the SHOW command until the modal
form is either hidden or unloaded. 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
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 ([email protected])
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
|"Send Message" (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$(KeyAscii)
KeyAscii = 0
End Select
result& = SendMessageBystring(FILE.hWnd, LB_FINDSTRING,
|0, searchme$)
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 ([email protected])]
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
15.I have [several] megabytes of memory. Why do I get an "out of
memory" error?
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?
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 ([email protected])]
See also the Shareware Custom Controls List FAQ file
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$(10) will give you a CR and LF.
[George Tatge ([email protected])]
24.How do I prevent multiple instances of my program?
In VB 3, the property App.PrevInstance is set to True if an
older instance of the program already exist.
The following piece of code, stolen from MS KB article Q102480,
will activate the old instance and then terminate itself:
Sub Form_Load ()
If App.PrevInstance Then
SaveTitle$ = App.Title
App.Title = "... duplicate instance." 'Pretty, eh?
Form1.Caption = "... duplicate instance."
AppActivate SaveTitle$
SendKeys "% R", True
End
End If
End Sub
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.
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 ([email protected])]
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?
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 ([email protected])]
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 ([email protected])]
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 ([email protected])]
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 ([email protected])]
The following tip is along the same lines, but with a code
sample. They are provided by Andy Dingley
([email protected]):
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 ([email protected]) 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 ([email protected])]
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 ([email protected])]
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
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?
Get the file FMDROP10.ZIP from ftp.cica.indiana.edu in the
vbasic directory. It is a good VB example of drag & drop. You
may also want to get the MSGBLAST VBX (3-64.ZIP at
ftp.microsoft.com in the MSDN directory) since you will need to
have access to Windows messages in order to do drag & drop -
unless you get a VBX to do it for you.
Also, the D&DSERVE example from Windows Tech Journal Aug 92
includes a DLL for this purpose. This is available from some ftp
sites.
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.
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 "8-
3.ZIP") or (better) from ftp.cica.indiana.edu. 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 ([email protected])]
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 ([email protected])]
18.How do I program the Novell NetWare API from VB?
Tom Tregilgas ([email protected]) 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
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.
19.Some Visual Basic 4 rumours
First, we have no special information. This is just rumours,
guessing, gossip! But since there are many questions about this
on the newsgroup, *and* Microsoft gives these controlled
leakages through their beta testers, we bring on some of it
(Please, don't start discussing NDA's on this group again!):
a. Two versions: 32-bit and 16-bit
Like Visual C++ 1.5, VB 4 will come with compilers for the
16-bit API from Windows 3.1 as well as a real 32-bit compiler
(or pseudocompiler) for Windows 4 (Chicago) bundled together.
b. New features will probably be inherited from VBA
i) Line continuation character " _" (space+underscore)
ii) 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
iii) FOR EACH .. NEXT statement allows you to make changes to
a group of objects at once better than FOR..NEXT. Object
groups are also something you may have to work closer
with in VB4.
iv) An OPTIONAL statement allows you to leave some Variant
parameteres undefined when calling a user-defined sub or
function. Also in VBA is an ARRAY function that returns
an array form a list supplied as parametres, and a
special optional ParamArray optional parameter of
Variants.
v) Boolean data type. Integer does the job, but this type
can preserve space if Microsoft codes it right.
vi) Byte data type? No, VBA does not support this. We can
dream, however.
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 compati-
bility, but be aware that OLE 2 and OCX is the way of the
future, at least if Microsoft gets it as they want.
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 ([email protected])]
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 ([email protected])]
2. 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).
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 ([email protected])]
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 misunder-
standing 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 and access the record with 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. It should
also be available on ftp.microsoft.com (I haven't verified
this). This file provides all the items necessary for
compatibility between VB 3.0 and Access 2.0.
[Fred Griffin ([email protected])]
The file COMLYR.EXE can be downloaded from ftp.microsoft.com. It
is located in the directory /softlib/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.
[All tips a to j by Andy
Dingley([email protected])]
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 ([email protected])]
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 ([email protected])]
11.How do I get a pitmap 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 ([email protected])]
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. Here is the latest information on the Setup Wizard
files as of 4/94:
File Current Size/Date Original Size/Date
SETUP EXE 19,056 08-23-93 15,312 04-28-93
SETUP1 BAS 27,268 10-14-93 26,452 04-28-93
SETUP1 FRM 15,341 01-21-94 16,331 04-28-93
SETUP1 FRX 770 01-21-94 770 04-28-93
SETUPK TXT 16,933 03-07-94 n/a
SETUPWIZ EXE 153,486 02-01-94 150,670 04-28-93
SETUPWIZ INI 3,844 02-18-94 3,638 04-28-93
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 ([email protected])]
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 ([email protected])]
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 ([email protected])]
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 ([email protected])]
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 ([email protected])]
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 ([email protected])]
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 Index for the
"Data Access
Guide"
3/7/94 GENERIC.EXE \VB\CDK\GENERIC Sample custom
control source
code
3/7/94 VBGRID.EXE GRID.VBX Grid control
3/7/94 VBHC505.EXE HC.EXE Standard and
HCP.EXE protected mode
WinHelp compiler
3/7/94 MSAJT.EXE MSAJT110.DLL Microsoft Access
Database Engine
3/8/94 MSCOMM.EXE MSCOMM.VBX Serial
Communications\co
ntrol
3/7/94 ORA110.EXE ORACLE.TXT Updated
ORACLE.TXT file
3/7/94 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 name and the word "update3.00".
Please inform the FAQ maintainer about newer versions.
I. VISUAL BASIC FOR APPLICATIONS (VBA)
1. Any tips for VB/Win 3 programmers moving to VBA?
You are in for some surprises. VBA is more unlike VB 3 than most
people thought. Especially the development environment is very
different, and the language puts more emphasis on objects. The
latter is a trend you can get used to for VB also.
For Excel 5 VBA, be aware that the environment is based on the
"workbook" idea Microsoft stole from Borland. Your controls will
be placed in one sheet, and the code will be in another.
Doubleclicking on the control to open the code window doesn't
help. You have to use the "Tools|Assign Macro" menu option.
Also, be aware that the list of events is nowhere close to what
VB3 supports! No GotFocus, no MouseMove, no nothing. You'll be
very confused if you try to look for "events" in the VBA docs!
2. Does VBA support VBXs?
No. If Microsoft have its way, VBX is a dead end. There will
never be 32-bit VBXs, but OCXs using OLE 2. VBA is more a subset
of VB 4 than VB 3, but it does not fully support OCX yet. It
will, though.
3. How do I access properties on my dialog boxes in VBA?
As noted above, VBA is a cultural chock for VB programmers. If
you create a textbox in VBA, call it txName and try to
cMyVar=txName.Text
the impolite interpreter will give you a "variable not defined"
error.
The magic is objects. You have to
Dim txName as Object
Set txName = DialogSheets("NameDialog".EditBoxes("txName"))
And then you can access your properties like you used to in good
ol' VB 3. (Anyone volunteer to beat senseless the guy who
thought out this?)
4. How do I use database routines from Excel VBA?
The documentation is somewhere between sparse and inexistant on
this topic. Any info on VBA and SQL would be much appreciated.
Here Microsoft breaks the tradition and you *can't* use database
objects, at least not the way you do in VB. Also, forget
dynasets.
I know nothing about databases in VBA. I just bring on the
following tips from various magazines:
Both SQLOpen and QueryGetData require a 'connection string'.
That's about what the doc's say about the parameter. What is it?
The doc is also tragically void of useful examples. Someone dug
up the following example:
"DSN=My data file;DBQ=c:\access\data.mdb;FIL=RedISAM;"
which is about as understandable as it looks. If you use an
empty string, you get a dialog which also can give you the
string into a spreadsheet cell.
Also, search for SQLREQUEST in the *main* help file for Excel 5
(not the VBA help!) for these examples of connection_string's:
dBASE DSN=NWind;PWD=test
SQL Server DSN=MyServer;UID=dbayer;PWE=123;Database=Pubs
ORACLE DNS=My Oracle Data Source;DBQ=MYSER VER;
|UID=JohnS;PWD=Sesame
There's a KnowledgeBase on Excel 5 on ftp.microsoft.com. Last
time I looked, it was void of database stuff. Still, it may be a
good idea to download it as the situation may have changed now.
*** END OF VB/WIN FAQ DOCUMENT ***
Very nice! Thank you for this wonderful archive. I wonder why I found it only now. Long live the BBS file archives!
This is so awesome! 😀 I’d be cool if you could download an entire archive of this at once, though.
But one thing that puzzles me is the “mtswslnkmcjklsdlsbdmMICROSOFT” string. There is an article about it here. It is definitely worth a read: http://www.os2museum.com/wp/mtswslnk/