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From: [email protected] (Kris Nosack)
Newsgroups: comp.lang.basic.visual.misc,comp.answers,news.answers
Subject: FAQ: (6/94) comp.lang.basic.visual.* VB/DOS Frequently Asked Questions
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Date: 5 Jun 1997 14:10:57 -0000
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Summary: Frequently asked questions concerning Visual Basic for DOS.
Keywords: FAQ VISUAL BASIC DOS
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Last-Modified: June 10, 1994

                  VISUAL BASIC FOR DOS (VBDOS)
               Commonly asked Questions & Answers
                        Section IX - B
              -----------------------------------

PREFACE:
This document is a compilation of frequently asked questions and their
answers about Visual Basic for DOS which have been gathered from the
comp.lang.basic.visual newsgroup.   Although some efforts have been
made to find obvious errors, there is no guarantee that the information in
this document is error-free.  The FAQ maintainer, or anyone else
associated with this document, assume NO liability for the content or use
of this document.  If you find any errors, please report them to the address
given below.

Most FAQs (including this one) are available at the anonymous ftp archive
site "rtfm.mit.edu".  All four parts of the VB FAQ may be found in the
directory "pub/usenet/news.answers/visual-basic-faq".

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.

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!
 Peter [email protected]   - VBDOS FAQ maintainer

Table of Contents:
1.   How do I use (create) global variables in VBDOS?
2.   Does VBDOS make standalone .exe files?
3.   What is the current version of the VBDOS compiler?
4.   How do I not make a text box beep when I hit the enter key?
5.   How does Visual Basic handle shelled tasks? How do I find out
    when they are finished.
6.   How do I break lines of long text into multiple lines of text in
    the msgbox?
7.   What's the difference between MODAL and MODELESS
    forms?
8.   When/Why should I use Option Explicit?
9.   Why doesn't PRINT or CLS from a frm module work?
10.  How do I invoke FKey traps which won't be triggered by other
    keys which share the same KeyCode?
11.  How do I boost memory available to VBDOS.EXE (the IDE)?
12.  My program runs in the IDE, but won't run when compiled??
13.  MISC. Programming TIPS:

-----------------------------------------------------------------------------

1.   How do I use (create) global variables in VBDOS?
    1.1. VBDOS provides the user with two types of global variables.
         These are both used in declarations of variables.

         To share variables between all subs and functions in a specific
         module, use the SHARED keyword. This makes that specific
         variable global _in that module_. For example:

                 DIM SHARED CancelFlag AS INTEGER

         would make the variable CancelFlag a global variable in that
         module.

         To share global variables between separate modules, use the
         COMMON keyword. For example:

                COMMON SHARED CancelFlag AS INTEGER

         would make the variable global between all modules that this
         common statement appears in, and since we are using the
         SHARED keyword also, this will also be shared in all the subs
         and functions in the modules which this declare statement
         appears. All COMMON statements must be matched between
         modules which the variables should be global in. For example,
         if you have one set of 10 COMMON statements in one module,
         and a different set of 10 COMMON statements in another
         module in the same project, you will get a 'Type Mismatch
         Error'. Make all COMMON blocks identical in all the modules
         in a specific project. (See Misc. Programming Tips Below).

2.   Does VBDOS make standalone .exe files?
    2.1. VBDOS can compile programs in two different ways (user
         option). It can compile programs to use a RUNTIME file (like
         a DLL) or can be compiled as a standalone .exe file.

3.   What is the current version of the VBDOS compiler?
    3.1. VBDOS is currently at version 1.0

4.   How do I not make a text box beep when I hit the enter key?
    4.1. 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  '0 (zero) is nothing
             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. Usually
         they will want to jump to the next control, like the Tab key
         does. You will then change the line KeyAscii=0 to KeyAscii=9
         (Key_Tab) in the example above.

         BTW, you'll also find this in the Microsoft VB
         KnowledgeBase. They add that you should set the MultiLine
         property to False. Of course.

5.   How does Visual Basic handle shelled tasks? How do I find out
    when they are finished.
    5.1. In VBDOS, all shelled tasks are completed before control
         returns to the program. No tasks are done while the DOS
         command is being executed.

6.   How do I break lines of long text into multiple lines of text in the
    msgbox?
    6.1. Use the append a chr$(13) to the end of the string to break
         lines into multiple lines. EG:

              msg$ = "This is line 1" + chr$(13)
              msg$ = msg$ + "This is line 2"
              MSGBOX msg$

7.   What's the difference between MODAL and MODELESS forms?
    7.1. 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

    7.2. Modeless forms are those which are shown but do not require
         immediate user input. Most child forms (in a MDI application)
         are typically modeless. To show a form modeless, use the
         syntax: MyForm.SHOW

8.   When/Why should I use Option Explicit?
    8.1. 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, it is suggested to use 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 single precisions. (Integers take up
         less memory).

         The OPTION EXPLICIT statement causes VB to 'disable' it's
         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 any bugs when a variable
         is misspelled.

9.   Why doesn't PRINT or CLS from a frm module work?
    9.1. To print information to the screen bypassing the desktop, the
         commands must be issued from a .BAS module. All
         PRINT/CLS output from a form module is directed to the nul:
         device.

10.  How do I invoke FKey traps which won't be triggered by other keys
    which share the same KeyCode?
    10.1.     To trap the only FKeys in events you need to use a
              combination of the KeyDown, KeyPress, and KeyUp
              events.

         The basic concept for this is that _all_ keys trap the UP &
         DOWN events, while only 'printable' characters trigger the
         KeyPress event. Thus, when a character key is pressed, it will
         trigger the KeyDown, the KeyPress, then the KeyUp events (in
         that order). While a FKey (or arrow, or tab, etc...) will trigger
         the KeyDown, then the KeyUp events (in that order).

         The following code uses a textbox tag property to decide
         whether a printable character is pressed or not.

              SUB Text1_KeyDown()
                   Text1.tag = "key"
              END SUB

              SUB Text1_KeyPress()
                   Text1.tag = ""
              END SUB

              SUB Text1_KeyUp()
                 IF Text1.tag = "key" then
                   '--PUT F-KEY HANDLER HERE----
                 ELSE
                   '--PUT OTHER KEY HANDLERS HERE----
                 END IF
              END SUB

11.  How do I boost memory available to VBDOS.EXE (the IDE)?
    11.1.     Try to have as much EMM available as possible.
              VBDOS.EXE allocates subroutines & functions which are
              < 16K into EMM.
    11.2.     To make more conventional mem availble, use the /S:n
              switch. This will make VBDOS.EXE use a specific
              amount of conventional memory. A good compromise
              between speed & memory is /S:340. The lower the n
              value, the slower the environment runs.
    11.3.     Running out of DGROUP usually causes most 'out of
              memory' errors. Possible causes are:
         11.3.1.Too many subs & functions exist. Each one takes up
              46 bytes of DGROUP.
         11.3.2.   Large static arrays. All static arrays are stored in
                   DGROUP. If a DIM statement is for a COMMON
                   SHARED statement, the array becomes static. Make
                   the COMMON SHARED statement appear before
                   the DIM statement to make the array Dynamic &
                   therefore will not be stored in DGROUP.
         11.3.3.   Variable Overhead. Each var has a 4 byte overhead
                   for _each_ module. For multiple modules projects
                   which use lots of Global (COMMON) statements,
                   this overhead is repeated for _each_ module.
    11.4.     Possible causes for running out conventional memory:
         11.4.1.   Not enough EMM.
         11.4.2.   Subs or functions which exceed 16K.
         11.4.3.   Large arrays. Non-variable length string arrays can
                   be stored in EMM using the /ea switch.

12.  My program runs in the IDE, but won't run when compiled??
    12.1.     Arrays are dynamic by default in the IDE, but when they
              are compiled, they are static by default. Therefore, they
              are stored in DGROUP instead of the far heap. Use
              '$DYNAMIC to make all arrays dynamic or use REDIM
              instead of DIM.
    12.2.     Program generates a "program memory overflow" during
              compile. You need to break a single module into multiple
              ones.


13.  MISC. Programming TIPS:
    13.1.     When useing the form designed, to continuously draw
              controls of a specific type, hold down the control key
              when clicking on the appropriate control from the tool-
              box.
    13.2.     Use the INCLUDE statement to manage large numbers of
              COMMON SHARED statements, user defined data types,
              or external function DECLARES. To use an include file,
              simply put all the VBDOS statements that will be shared
              into a single file. Save the file as something appropriate.
              (Typical naming convention is to use an extension of .BI
              for basic include files). Then simply insert the line:
                       'INCLUDE: 'foobar.bi'
              into either your .BAS module, or the module level code
              in a form.

--
Kris Nosack      [email protected]

>>>--->  Be strange, but not a stranger!  <---<<<

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