FAQ: VB Programming in VB 3.0

The information in this article applies to:

- Standard and Professional Editions of Microsoft Visual Basic for

  Windows, version 3.0

This article covers some of the most Frequently Asked Questions (FAQ) about non-technical issues for Microsoft Visual Basic for Windows. You can find this and other FAQ articles by querying on the keyword "FAQ." You can find additional general references in the Microsoft Knowledge Base by searching on "article list."

1. Q. I'm getting error #6 "Overflow." What's wrong?

   A. The most common cause of an overflow error is exceeding the upper or
      lower bounds of either the type of a data variable or the limits of
      the property for an object.

      Query on "Data Types" in the Visual Basic online Help to determine
      the upper and lower bounds for various data types (integer, long,
      and so forth).

      Additionally, the following detail more well-known causes of this
      error:

      ARTICLE-ID: Q100190
      TITLE     : BUG: Overflow Error When CurrentX Or CurrentY Greater
                  Than 32K

      ARTICLE-ID: Q81953
      TITLE     : Overflow Error Plotting Points Far Outside Bounds of
                  Control

      ARTICLE-ID: Q74517
      TITLE     : FIX: Overflow Error If Print Long String to Form or
                  Printer

      ARTICLE-ID: Q106495
      TITLE     : BUG: VB Printer.Width/Height Values Incorrect for Plotter

      ARTICLE-ID: Q113439
      TITLE     : PRB: Converting MBF to IEEE in Visual Basic for Windows

      ARTICLE-ID: Q95499
      TITLE     : BUG: Stack Fault May Occur If Trapping Divide By Zero

      ARTICLE-ID: Q105808
      TITLE     : BUG: Overflow in VB version 3.0 ICONWRKS Sample Program

2. Q. Where are the corrections to the manuals listed?

   A. Get out your red pen and see the following article in the
      Microsoft Knowledge Base:

      ARTICLE-ID: Q100369
      TITLE     : Corrections for Errors in Visual Basic Version 3.0
                  Manuals

3. Q. How do you tell if a file exists?

   A. Use the DIR$ function.

4. Q. Now that I found the file, how do I delete it?

   A. Use the KILL$ function.

5. Q. I'm getting "Illegal Function Call." What's wrong?

   A. Here is a list of Knowledge Base articles that describe how "Illegal
      Function Call" (error #5) can be generated:

      ARTICLE-ID: Q113332
      TITLE     : BUG: AddNew Method Gives Error: Illegal Function Call

      ARTICLE-ID: Q94778
      TITLE     : BUG: Illegal function call / Division By Zero Errors

      ARTICLE-ID: Q88477
      TITLE     : PRB: SetFocus During Form Load May Cause Illegal Function
                  Call

      ARTICLE-ID: Q87773
      TITLE     : PRB: SendKeys May Return Illegal Function Call Error

      ARTICLE-ID: Q84547
      TITLE     : PRB: DateValue Argument Gives "Illegal Function Call"
                  Error

      ARTICLE-ID: Q77393
      TITLE     : BUG: DateSerial Does Not Give Error for Invalid Month or
                  Day

      Additionally, don't exceed the byte value range of 0 to 255 when
      dealing with characters. For example, if you add 50 to the extended-
      ASCII character CHR$(230) and assign it to a string in Basic, you get
      an "Illegal function call" error.

6. Q. If I have invisible menus on my form, why do the wrong menus appear
      when I choose a pop-up menu?

   A. Visual Basic is not firing the correct menu choice on a pop-up menu
      for a menu whose visible property is set to False. This has been
      confirmed to be a bug in Visual Basic 3.0.

      To work around this problem, either:

       - Make the first menu on the form visible.

         -or-

       - Place all pop-up menus on a separate form. Then you can leave all
         the menus on your pop-up menus visible, but make the form that
         contains them invisible. To make the form invisible, set the
         form's visible property to false. You can invoke pop-up menus from
         other forms by referring to the form name and then the menu name,
         as in this example:

            PopupMenu Form2.Menu2

      For additional information, please see the following article in
      the Microsoft Knowledge Base:

      ARTICLE-ID: Q116058
      TITLE     : Incorrect Popup Menu Events Fired with Invisible Menus

7. Q. How can I create a transparent bitmap, or layer multiple bitmaps on
      top of each other?

   A. If bitmaps are layered on top of one another, the overlapped regions
      will not show through the bitmaps that are on top unless the upper
      bitmap has transparent regions. Article Q94961 shows how to create a
      transparent bitmap from Visual Basic using Windows APIs.

      For additional information, please see the following article in
      the Microsoft Knowledge Base:

      ARTICLE-ID: Q94961
      TITLE     : How to Create a Transparent Bitmap Using Visual Basic

8. Q. How can I find out what corrections have been made to the Visual
      Basic manuals?

   A. As the errors are found and reported, they are gathered together into
      article Q100369 in the Knowledge Base.

      For additional information, please see the following article in
      the Microsoft Knowledge Base:

      ARTICLE-ID: Q100369
      TITLE     : Corrections for Errors in Visual Basic Version 3.0
                  Manuals

9. Q. I'm getting "Out of Memory" and my machine has XX megabytes free,
      what's wrong?

   A. "Out of Memory" is typically one of two problems. First, you may have
      exceeded the limits of one of Visual Basic's internal 64K tables.
      Second, "Out of Memory" seems to be a catchall error for other, less
      specific problems.

      To prevent legitimate "Out of Memory" messages consult with Appendix
      D (Specifications and Limitations) and Chapter 11 (Optimizing Your
      Application for Size and Speed) in the "Programmer's Guide." Then
      consult article Q112860 (General Memory Management in Visual Basic
      Vers 3.0 for Windows), which was written in conjunction with the
      developer who implemented VB's memory management, and discusses how
      to deal with this issue.

      For the other case, consult the following Knowledge Base articles as
      known sources of the "Out of Memory" error when the cause may not be
      an actual memory leak.

      For additional information, please see the following articles in
      the Microsoft Knowledge Base:

      ARTICLE-ID: Q97136
      TITLE     : BUG: OLE DataText Prop Doesn't Free Memory When Object
                  Closed

      ARTICLE-ID: Q103438
      TITLE     : BUG: Out of Memory w/ MSOLE2.VBX When SHARE.EXE Not
                  Loaded

      ARTICLE-ID: Q107769
      TITLE     : PRB: Out of Memory Error Using VB Outline Control

      ARTICLE-ID: Q113031
      TITLE     : BUG: ActiveControl Property of Screen Object Loses Memory

      ARTICLE-ID: Q110989
      TITLE     : BUG: Out of Memory Error When Adding 35-50 Pen Controls

      ARTICLE-ID: Q113031
      TITLE     : BUG: ActiveControl Property of Screen Object Loses Memory

      ARTICLE-ID: Q102069
      TITLE     : BUG: Out of Memory w/ Var Named
                  ClientLeft/Top/Width/Height

      ARTICLE-ID: Q76983
      TITLE     : BUG: FormName Not in Correct Order After Out of Memory
                  Error

10. Q. How do I capture/print a picture control with embedded controls and
       graphics?

    A. Article Q85978 offers a very handy routine called PrintWindow(). In
       the context of the article, PrintWindow() is used to print a form's
       client area to a printer. However PrintWindow() does not really care
       much about the source of the image or the destination. All it
       requires is a hWnd (window handle) property from the source, and a
       hDC (device context) and the ability to receive a bitmap for the
       destination.

       Therefore, you can use PrintWindow() to capture an image of a
       picture control with embedded controls and graphics into either a
       printer object, or to another picture control.

       For additional information, please see the following article in
       the Microsoft Knowledge Base:

       ARTICLE-ID: Q85978
       TITLE     : Print Form or Client Area to Size on PostScript or PCL
                   Printer

11. Q. How can I be sure that all my forms are unloaded correctly?

    A. You can use the following code in the unload event of the form that
       has triggered your applications exit.

       Dim i%
       While forms.Count > 1
        ' Find first form besides "me" to unload
         i% = 0
         While forms(i%).Caption = Me.Caption
           i% = i% + 1
         Wend
         Unload forms(i%)
       Wend

       ' Last thing to be done...
       End

12. Q. How do I make my Visual Basic app Windows '95 logo compliant?

    A. A difficult task prior to Win '95 shipping, but there are some
       things you can do to move into the right direction. The Microsoft
       Windows logo department has prepared a mailing on the Windows logo
       transition. You may access this document by calling the faxback
       service at (800) 426-9400. Choose option 2 for Developer Solutions,
       then option 1 for the faxback service, then press 1 for a complete
       index of available documents. Or choose document #130 for specific
       information on the Windows '95 logo program.

13. Q. How do I make my Visual Basic app Office-compatible?

    A. This is a program that is available to Independent Software Vendors.
       You can call to find out what is required by ordering the Microsoft
       Office Compatible Information Kit (Order Part Number 098-55847) at
       (800) 426-9400.