WELCOME TO THE SIXTH EDITION OF THE VBPJ TECHNICAL TIPS SUPPLEMENT!
These tips and tricks were submitted by professional developers using Visual Basic 3.0,
Visual Basic 4.0, Visual Basic 5.0, Visual Basic for Applications (VBA), and Visual Basic
Script (VBS).
VB4 16/32
Level: Intermediate
USE BOOLEAN VARIABLES FOR CHECK-BOX VALUES
Visual Basic specifies a Boolean's default values as zero for False and -1 for True. You
may save and set the value of a check box, based on the absolute value of a Boolean
variable, as these correspond to the intrinsic constants vbUnchecked and vbChecked:
Dim bBool as Boolean bBool = True '//If bBool = 0 the checkbox will be '//unchecked, if it is anything else it will '//be checked. Check1.Value = Abs(bBool)
-Jeremy Boschen, Branchburg, New Jersey
VB4 16/32
Level: Intermediate
DISPLAY HORIZONTAL SCROLLBAR
Unlike the Windows 95 common controls, the standard list box doesn't have a horizontal
scrollbar when list items are too wide to fit within the list box. Fortunately, it's not
hard to direct a list-box control to display a horizontal scrollbar.
Add this code to a form's Load event. It fills a list box with 100 long strings and calls
SetHScroll to show a horizontal scrollbar in the list box:
Private Sub Form_Load() Dim i As Integer For i = 1 To 100 List1.AddItem CStr(i) & _ " bottle(s) of beer on the wall." Next i SetHScroll Me, List1, List1.List(0) End Sub
Add this code, which includes the required API declarations and the SetHScroll routine, to a BAS module. The SetHScroll routine uses the SendMessage API function to send the LB_SETHORIZONTALEXTENT message to a list box. The last argument is an item from the list, preferably one of the longest items. SetHScroll determines the string's width in pixels and passes this value to the list box along with the LB_SETHORIZONTALEXTENT message. The list box sets its horizontal extent to this value, and if it is wider than the list-box control, the list box displays a horizontal scrollbar:
#If Win32 Then Declare Function SendMessage Lib "user32" _ Alias "SendMessageA" ( _ ByVal hwnd As Long, ByVal wMsg As Long, _ ByVal wParam As Long, lParam As Long) As Long #Else Declare Function SendMessage Lib "user32" _ Alias "SendMessageA" ( _ ByVal hwnd As Integer, ByVal wMsg As Integer, _ ByVal wParam As Integer, lParam As Long) As Long #End If 'Define constant for message to list-box control Const LB_SETHORIZONTALEXTENT = &H194 Public Sub SetHScroll(Frm As Form, Ctrl As _ Control, strText As String) Dim nScaleMode As Integer Dim nTextWidth As Integer 'Scale in pixels for window message nScaleMode = Frm.ScaleMode Frm.ScaleMode = 3 'Get the width, in pixels, of the text string nTextWidth = Frm.TextWidth(strText) 'Send a message to the list box SendMessage Ctrl.hwnd, _ LB_SETHORIZONTALEXTENT, nTextWidth, 0 'Restore previous scale mode Frm.ScaleMode = nScaleMode End Sub
-Peter Gomis, Shelton, Connecticut
VB4 16/32, VB5
Level: Beginning
GET THE TRUE MEMBER OF AN OPTION ARRAY
Setting an element in an array of option buttons to True is easy. Click on the option
button, or use this code:
OptionArray(ThisOne) = True
ThisOne is the Index of the member you want to be selected. Getting the True member of an option array is not so simple. Because you need to perform this kind of task in almost any reasonably complex program, adding this function to your code library or generic module simplifies the task. You don't need to know the array size in advance:
Function OptionTrueIs(OptionArrayName As _ Variant) As Integer ' Returns the index of the True ' member of an option array Dim Ctl as Control For Each Ctl in OptionArrayName If Ctl.Value = True Then OptionTruels = Ctl.Index Exit For End If Next End Function
You can use the routine to set a Public variable from a Properties sheet using this format:
SomePublicVariable = OptionTrueIs(SomeOptionArray())
Or use this code to save a program variable between runs:
SaveSetting("MyApp", "OptionSettings", _
"OptionKey", OptionTrueIs(SomeOptionArray())
Load the routine using this code:
SomeOptionArray(GetSetting("MyApp", "", _
"OptionSettings", "OptionKey",0))=True
Or you can load the routine using this code:
SomePublicVariable = GetSetting("MyApp", "", _
"OptionSettings", "OptionKey",0)
Use this code to control a Select Case structure:
Select Case OptionTrueIs(SomeOptionArray()) Case 0: ' This code will execute if element 0 ' of SomeOptionArray() is selected. End Select
Use this code to test a condition:
If OptionTrueIs(SomeOptionArray()) = SomeValue Then ' This code will execute if element ' SomeValue of SomeOptionArray() is ' selected. End If
-Roger Gilchrist, Ourimbah, New South Wales, Australia
VB4 16/32, VB5
Level: Intermediate
DEBUG ERROR HANDLERS
Visual Basic gives you the option to turn off error trapping in your projects. This is
useful when you suspect that your error handlers contain errors themselves. To turn off
error handling globally, choose Options from the Tools menu. Select the General tab, and
select Break on All Errors. The next time you run your project in the development
environment, Visual Basic will break whenever an error occurs in your code, whether the
error is trapped or not.
-Jeffrey P. McManus, San Francisco, California
VB3, VB4 16/32, VB5
Level: Beginning
PROTECT DATA WITHIN MODULES
Use Private variables in BAS modules to protect data that the module's routines must
access, but which should be hidden from the rest of the application:
Dim hidden_data As Integer Function GetData() As Integer GetData = hidden_data * 2 End Function
-Rod Stephens, Boulder, Colorado
VB3, VB4 16/32, VB5, VBA
Level: Intermediate
CONVERT A TEXT FILE INTO ACCESS MDB
It can be troublesome to convert a text file into an Access database. It takes a lot of
time to open the file for sequential access and create new records using the AddNew
method. Instead, use the Text ISAM driver and SQL to do the job for you. First, create a
SCHEMA.INI file for the text file and place it in the same directory as the text file. Use
this code to convert the database:
Dim db As Database, tbl as TableDef
Set db = DBEngine.CreateDatabase(App.Path & _
"\mymdb.mdb", dbLangGeneral, dbVersion_0)
Set tbl = db.CreateTableDef("Temp")
tbl.Connect = "Text;database=c:\vbpj\data"
tbl.SourceTableName = "Customer#txt"
db.TableDefs.Append tbl
db.Execute "Select Temp.* into NewTable from Temp"
db.TableDefs.Delete tbl.Name
db.Close
Set tbl = Nothing
Set db = Nothing
Now, you only need to create indexes. You can use this method to convert text files in excess of 100,000 records in a few seconds.
-Richard Mageau, Warren, Rhode Island
VB3, VB4 16/32, VB5, VBA
Level: Intermediate
QUICK AND EASY SCHEMA.INI
To create a SCHEMA.INI file for a text file quickly and easily, let the ODBC setup and
drivers do it for you. Go to the Control Panel and start ODBC. Click on the Add button and
select the Text driver. Click on the Options button and describe how to arrange the text
file. If your text file has a header record, click on the Guess button, and the
ColumnNames will be filled out for you. On the last screen, choose Cancel to avoid setting
up the data source. Check the directory where the text file resides, and you'll find a new
SCHEMA.INI file.
-Richard Mageau, Warren, Rhode Island
VB4 16/32, VB5
Level: Intermediate
CONTROL ARRAYS ARE COLLECTIONS
Most VB4 programmers know they can access a form's control collection using a For Each
loop. Many, however, are not aware that individual control arrays are actually
collections. This knowledge can be helpful when checking the properties of several
controls, especially when new controls are loaded at run time. You might wish to create a
form in which all text boxes must be filled out. Instead of assigning a unique name to
each text box, create a control array with each text box named txtFields. You can use this
name as you use the name of any collection in a For Each loop:
Dim v For Each v In txtFields If v.Text = "" Then MsgBox "All fields must be " & _ "filled out.", vbExclamation + _ vbOKOnly Exit Sub End If Next
Because txtFields is a collection, you can also determine how many text boxes are in the array by checking the value of txtFields.Count. For more information, see Karl E. Peterson's Q&A column, "The Keys to Your Controls" [VBPJ August 1997].
-Daniel Buskirk, The Bronx, New York
VB3, VB4 16/32, VB5, VBA
Level: Beginning
SET A FLAG TO TRUE/FALSE
When you want to set a flag to True or False, depending on the results of a comparison,
you don't need to use an If statement like this:
If x > 3 then Greater = True Else Greater = False End If
Logical operators return a value like any other operator. Instead, use this syntax:
Greater = x > 3
This way, you move directly to the result of the comparison in your flag. It is shorter and faster than the form example.
-Martin Girard, Chicoutimi, Quebec, Canada
VB3, VB4 16/32,VB5, VBA
Level: Intermediate
SUPPORT A FONT THE PRINTER DOESN'T
Often users print from applications that support a font the printer doesn't. An error
occurs if an application uses a statement such as Printer.Print SomethingToPrint following
a Printer.FontName = FontName statement, and the printer doesn't support the FontName.
You can use this function procedure as a corrective measure after the error is trapped.
This function procedure uses only one parameter-the font names specified by the
application. If the printer doesn't support the font, the function procedure returns a
font on the printer most similar to the font in the application:
Function FindFont (SpecifiedFont As String) 'find the font on the printer which is the 'closest to the font name passed to this procedure: Dim i%, tempfont% For i% = 1 To Printer.FontCount tempfont = InStr(Printer.Fonts(i%), SpecifiedFont) 'Get font's position. If tempfont <> 0 Then Exit For End If Next If tempfont <> 0 Then FindFont = Printer.Fonts(i%) Else 'take an action if no similar fonts are 'found on this printer End If End Function
In your error handler, use this function in conjunction with the FontName property of the Printer object. After you take this corrective measure, resume the execution of your program:
Printer.FontName = FindFont(SpecifiedFont) Resume Next
-Brian Hunter, Brooklyn, New York
VB4 32, VB5, VBA
Level: Intermediate
CENTER FORMS WITH TASKBAR VISIBLE
Just about every VB developer uses the Move (Screen.Width - Width) \ 2, (Screen.Height -
Height) \ 2 method to center the forms on screen. However, when the user has the Windows
95 or NT 4.0 taskbar visible, your form centers on screen but doesn't take into account
the position of the taskbar itself. The CenterForm32 routine centers a form in available
screen area, taking into account the taskbar. Add this code to the Declarations section of
a module, and put the code CenterForm32 Me on the Form_Load event of the forms you want to
center:
Option Explicit Private Const SPI_GETWORKAREA = 48 Private Declare Function _ SystemParametersInfo& Lib "User32" _ Alias "SystemParametersInfoA" ( _ ByVal uAction As Long, _ ByVal uParam As Long, lpvParam As Any, _ ByVal fuWinIni As Long) Private Type RECT Left As Long Top As Long Right As Long Bottom As Long End Type Public Function CenterForm32 (frm As Form) Dim ScreenWidth&, ScreenHeight&, _ ScreenLeft&, ScreenTop& Dim DesktopArea As RECT Call SystemParametersInfo ( _ SPI_GETWORKAREA, 0, DesktopArea, 0) ScreenHeight = (DesktopArea.Bottom - _ DesktopArea.Top) * Screen.TwipsPerPixelY ScreenWidth = (DesktopArea.Right - _ DesktopArea.Left) * Screen.TwipsPerPixelX ScreenLeft = DesktopArea.Left * Screen.TwipsPerPixelX ScreenTop = DesktopArea.Top * Screen.TwipsPerPixelY frm.Move (ScreenWidth - frm.Width) _ \ 2 + ScreenLeft, (ScreenHeight - _ frm.Height) \ 2 + ScreenTop End Function
-Miguel Santos, Aveiro, Portugal
VB3, VB4 16/32
Level: Intermediate
DISPLAY TOOLTIPS
You can easily duplicate the tooltips that appear when you float the mouse over a button
in Microsoft's products. This code displays the tooltip in the lower right-hand corner of
the control (normally a button):
' xTip: string to display as the tip ' xCtrl: control you want the tip to show for. ' xTipControl: control being used to display ' the tip (an SSPanel) Public Sub ShowTip(xTip As String, xCtrl As _ Control, xTipControl As Control) xTipControl.Left = xCtrl.Left + xCtrl.Width xTipControl.Top = xCtrl.Top + xCtrl.Height xTipControl.Caption = xTip xTipControl.Visible = True End Sub
This code hides the tooltip:
' xTipControl : control which is being used to ' display the tip. Public Sub HideTip(xTipControl As Control) xTipControl.Visible = False End Sub
Place the ShowTip function in the MouseMove event of the control(s) for which you want to display a tip. Place the HideTip function in the other control(s) for which you don't want to display a tip:
Sub Command1_MouseMove (Button As Integer, _ Shift As Integer, X As Single, Y As Single) ShowTip "Command1", Command1, SSPanel1 End Sub Sub Command2_MouseMove (Button As Integer, _ Shift As Integer, X As Single, Y As Single) ShowTip "Command2", Command2, SSPanel1 End Sub Sub Form_MouseMove (Button As Integer, _ Shift As Integer, X As Single, Y As Single) 'No tooltip for form HideTip Text1 End Sub
-Andy McInturff, Erwin, Tennessee
VB5
Level: Intermediate
USE SUBSCRIPTS AND SUPERSCRIPTS
You can use subscripts and superscripts in a RichTextBox control. To prevent the control
from truncating text that is raised or lowered too far, reduce the characters' size
accordingly:
Private Sub Form_Load() RichTextBox1.Font.Name = "Times New Roman" RichTextBox1.Font.Size = 10 RichTextBox1.Text = "H2SO4" ' Move the numbers down 2 points. MakeSubscript RichTextBox1, 1, 1, -2 MakeSubscript RichTextBox1, 4, 1, -2 End Sub Private Sub OffsetRichText(box As _ RichTextBox, start As Integer, _ length As Integer, offset As Integer) box.SelStart = start box.SelLength = length box.SelFontSize = box.Font.Size + offset box.SelCharOffset = -ScaleY(offset, _ vbPoints, vbTwips) box.SelStart = 0 box.SelLength = 0 End Sub
-Rod Stephens, Boulder, Colorado
VB4 32
Level: Advanced
PLAY WAV SOUNDS FROM RESOURCE FILES
Everyone loves a good sound bite. You can use the PlaySound() function in the Windows
Multimedia DLL (WINMM.DLL) to play a wave (WAV) file that is stored as a resource.
Although you can do this using the sndPlaySound function, sndPlaySound requires you to
find, load, lock, unlock, and free the resource. PlaySound achieves all of this with a
single line of code.
Add this line of code to your resource file (RC) designating a name for the sound and its
location:
MySound WAVE c:\music\vanhalen.wav
The name MySound is a placeholder for a name you supply to refer to this WAV resource
in code.
Compile the resource file using the resource compiler (RC.EXE) to create a RES file.
Include this file in your VB project. Use this code to play the sound:
Private Declare Function PlaySound Lib _ "winmm.dll" Alias "PlaySoundA" ( _ ByVal lpszName As String, _ ByVal hModule As Long, _ ByVal dwFlags As Long) As Long Private Const SND_ASYNC& = &H1 ' Play asynchronously Private Const SND_NODEFAULT& = &H2 ' Silence if sound not found Private Const SND_RESOURCE& = &H40004 ' Name is resource name or atom Dim hInst As Long ' Handle to Application Instance Dim sSoundName As String ' String to hold sound resource name Dim lFlags As Long ' PlaySound() flags Dim lRet As Long ' Return value Private Sub Command1_Click() hInst = App.hInstance sSoundName = "MySound" lFlags = SND_RESOURCE + SND_ASYNC + _ SND_NODEFAULT lRet = PlaySound(sSoundName, hInst, lFlags) End Sub
Note that you must compile this application and run the resulting EXE directly for this code to work because it relies on the application instance handle. While in the VB development environment, App.Instance returns an instance handle to the running VB32.EXE process, not the application under development. For a complete description of PlaySound(), refer to the Multimedia section of the Win32 SDK.
-Steve Davis, Gaithersburg, Maryland
VB3, VB4 16/32, VB5
Level: Intermediate
A BETTER WAY TO SWAP TWO INTEGER VARIABLES
The algorithm shown in the tip, "Swap Values Using Only Two Variables"
["101 Tech Tips for VB Developers, Supplement to the February 1997 issue of VBPJ,
page 25], crashes not only if (a+b) >= 32K, but if (a+b) < -32K also. I usually use
this algorithm instead:
a = a Xor b: b = a Xor b: a = a Xor b.
This works for almost any programming language.
-Alex Bootman, Foster City, California
VB4 32, VB5
Level: Intermediate
WRITE LESS CPU-BOUND ANIMATIONS
When doing animation, such as scrolling a label or using picture boxes, I first used the
method described by Eric Bernatchez ("Smoother Control Animation," "101
Tech Tips for VB Developers," Supplement to the February 1997 issue of VBPJ, page
21). However, I found that while in the Do Loop, the CPU usage is 100 percent! Windows NT,
Windows 95, and Win32 have an API call named SLEEP. This call suspends the called
application for the supplied amount of milliseconds. When you change the code, the CPU
usage on a Pentium 100 drops to 10 percent:
Declare Sub Sleep Lib "kernel32" ( _ ByVal dwMilliseconds As Long) Public Sub Scrolling() Label1.Left = Me.Width Do Sleep 100 Label1.Left = Label1.Left - 60 DoEvents Loop Until Label1.Left <= -(Label1.Width + 15) End Sub
The only problem with this method is that your app won't respond to user input while it sleeps, so don't let it sleep too long.
-Derek Robinson, Pretoria, South Africa
VB4 16/32, VB5, VBA
Level: Intermediate
EXPORT DATA TO ISAM DATABASES
Use this code to get data out to different formats without requiring a complete copy of
the DBMS on the user machine. Create a new project with a command button, and copy this
code into the button's Click event:
Dim db As Database Set db = Workspaces(0).OpenDatabase _ (App.Path & "\biblio.mdb") ' commented out syntax line followed by ' working example ' db.Execute "SELECT tbl.fields INTO ' [dbms type; DATABASE=path].[unqualified ' file name] FROM [table or tables]" db.Execute "Select * into [dBASE III; DATABASE=" & "C:\My Documents]. [testa] FROM [authors]
By using the brackets and the dot operator, you get a completely proper output in the
ISAM database type of your choice. Also, if you choose Text as the database type, the
statement creates a SCHEMA.INI for you automatically, or adds a new section for your new
data file to a SCHEMA.INI already in the path folder.
You can do any kind of export the client wants without using a DBMS on the machine. This
makes your life easier when you notice that some users running Word 97 have problems
mail-merging with text files you originally created with Write# and Print# methods.
-Robert Smith, San Francisco, California
VB3, VB4 16/32, VB5
Level: Intermediate
RANDOM VALUES WITHOUT DUPLICATES
This code produces a "random" sequence of integers between specified Lower and
Upper values without duplication. On the first call to the Shuffle routine with new values
for Upper and Lower, Shuffle performs an efficient prime factorization, computes the
constants for a linear sequence generator, and uses Randomize to generate a seed value.
Each subsequent call with the same value of Upper and Lower uses this generator to return
the next "random" number in the sequence. The sequence does not repeat until all
possible values have been returned. This code fills the array with 20 random numbers
between 1 and 100, without duplication:
For I = 1 To 20 num(I)=Shuffle(1,100) next I
Here is the Shuffle routine:
Static Function Shuffle (Lower As Integer, _ Upper As Integer) As Integer Static PrimeFactor(10) As Integer Static a As Integer, c As Integer, b As Integer Static s As Integer, n As Integer Dim i As Integer, j As Integer, k As Integer Dim m As Integer If (n <> Upper - Lower + 1) Then n = Upper - Lower + 1 i = 0 n1 = n k = 2 Do While k <= n1 If (n1 Mod k = 0) Then If (i = 0 Or PrimeFactor(i) <> k) Then i = i + 1 PrimeFactor(i) = k End If n1 = n1 / k Else k = k + 1 End If Loop b = 1 For j = 1 To I b = b * PrimeFactor(j) Next j If n Mod 4 = 0 Then b = b * 2 a = b + 1 c = Int(n * .66) t = True Do While t t = False For j = 1 To I If ((c Mod PrimeFactor(j) = 0) Or _ (c Mod a = 0)) Then t = True Next j If t Then c = c - 1 Loop Randomize s = Rnd(n) End If s = (a * s + c) Mod n Shuffle = s + Lower End Function
-John W. Starner, El Paso, Texas
VB4 16/32, VB5
Level: Intermediate
COMMENT MULTIPLE LINES
VB provides only single-line comment functions: "REM" and "'". If
you're looking for another way to comment out a block of code, use conditional compilation
in VB4 instead. Define "COMMENT = 0" in the Conditional Compilation Arguments
field on the Advanced tab in the Options dialog of the Tools menu:
Public Sub TestingSub() Print "This subroutine is used to" Print "demonstrate block" Print "commenting in VB." #If COMMENT then Print "This line will not be printed." Print "Since this is commented out." Print "VB ignores these lines during compilation." #End If End Sub
This trick also works with VB5, but you might find the Comment Block command on the Edit toolbar much handier.
-Frewin Chan, Scarborough, Ontario, Canada
VB4 32, VB5
Level: Advanced
CHANGE DISPLAY SETTINGS ON THE FLY
When writing a game for Windows 95, set the display resolution to 640-by-480, set the
color palette to True Color when it runs, and restore it to its initial mode when it ends.
Use this function to implement it:
'- Declares Private Declare Function lstrcpy _ Lib "kernel32" Alias "lstrcpyA" _ (lpString1 As Any, lpString2 As Any) _ As Long Const CCHDEVICENAME = 32 Const CCHFORMNAME = 32 Private Type DEVMODE dmDeviceName As String * CCHDEVICENAME dmSpecVersion As Integer dmDriverVersion As Integer dmSize As Integer dmDriverExtra As Integer dmFields As Long dmOrientation As Integer dmPaperSize As Integer dmPaperLength As Integer dmPaperWidth As Integer dmScale As Integer dmCopies As Integer dmDefaultSource As Integer dmPrintQuality As Integer dmColor As Integer dmDuplex As Integer dmYResolution As Integer dmTTOption As Integer dmCollate As Integer dmFormName As String * CCHFORMNAME dmUnusedPadding As Integer dmBitsPerPel As Integer dmPelsWidth As Long dmPelsHeight As Long dmDisplayFlags As Long dmDisplayFrequency As Long End Type Private Declare Function _ ChangeDisplaySettings Lib _ "User32" Alias "ChangeDisplaySettingsA" (_ ByVal lpDevMode As Long, _ ByVal dwflags As Long) As Long '- code ' Here is the function that sets the display ' mode. Width is the width of screen, Height ' is the height of screen, Color is the number ' of bits per pixel. Set the Color value to -1 ' if you only want to change the screen ' resolution. Public Function SetDisplayMode(Width As _ Integer,Height As Integer, Color As _ Integer) As Long Const DM_PELSWIDTH = &H80000 Const DM_PELSHEIGHT = &H100000 Const DM_BITSPERPEL = &H40000 Dim NewDevMode As DEVMODE Dim pDevmode As Long With NewDevMode .dmSize = 122 If Color = -1 Then .dmFields = DM_PELSWIDTH Or DM_PELSHEIGHT Else .dmFields = DM_PELSWIDTH Or _ DM_PELSHEIGHT Or DM_BITSPERPEL End If .dmPelsWidth = Width .dmPelsHeight = Height If Color <> -1 Then .dmBitsPerPel = Color End If End With pDevmode = lstrcpy(NewDevMode, NewDevMode) SetDisplayMode = ChangeDisplaySettings(pDevmode, 0) End Function
You can change the display mode easily with this function. For example, write this code that changes the resolution to 640-by-480 and the color palette to 24-bit True Color:
i = SetDisplayMode(640, 480, 24)
If the function is successful, it returns zero.
-Huang Xiongbai, Shanghai, China
VB5
Level: Intermediate
CREATE A NEW PROJECT TEMPLATE
Upon initialization, the VB5 IDE presents you with a list of project types, such as
Standard EXE or ActiveX EXE. You can also create new project types yourself by creating
templates and saving them to the Projects folder in your Templates directory. To find the
Templates directory on your system, look in Options under the Tools menu, then select the
Environment tab. The Templates directory is listed at the bottom of the dialog. After you
create a template, its icon appears with the predefined project types whenever you start
VB or use the FileNew command.
What is a template anyway? It's simply a project you save to the Projects folder. It
includes all forms, controls, classes, code, and other elements in the project. It serves
as a foundation for a new project and can have as much or as little prebuilt content as
you need.
-Ron Schwarz, Mt. Pleasant, Michigan
VB3, VB4 16/32, VB5
Level: Beginning
SELECT TEXT-BOX CONTENTS ON ENTRY AUTOMATICALLY
Many commercial apps select the contents of the text box automatically whenever it gets
focus. You can do the same in your apps with a few VB statements. Invoke the SelStart and
SelLength functions within a TextBox control's GotFocus event:
Private Sub Text1_GotFocus() Text1.SelStart = 0 Text1.SelLength = Len(Text1) End Sub
Or place the code in a public Sub procedure and call it from any text box in your project:
Private Sub Text2_GotFocus() PreSel Text2 End Sub Public Sub PreSel(txt As Control) If TypeOf txt Is TextBox Then txt.SelStart = 0 txt.SelLength = Len(txt) End If End Sub
Because you can call the PreSel procedure from anywhere, you should limit the procedure to acting on TextBox controls to prevent errors. The TypeOf function tests if you've passed the procedure a TextBox control, and if not, it skips over the selection code.
-Ron Schwarz, Mt. Pleasant, Michigan
VB3, VB4 16/32, VB5
Level: Intermediate
CLOSE FORMS UNIFORMLY
To close forms uniformly, treat the system menu's Close command and your File menu's Exit
command in the same manner. In your Exit command, simply unload the form. Let the form's
QueryUnload event handler see if it is safe to exit. If not, cancel the Exit by setting
Cancel to True:
Private Sub mnuFileExit_Click()
Unload Me
End Sub
Private Sub Form_QueryUnload(Cancel _
As Integer, UnloadMode As Integer)
Cancel = (MsgBox("Are you sure you " & _
"want to exit?", vbYesNo) = vbNo)
End Sub
-Rod Stephens, Boulder, Colorado
VB3, VB4 16/32, VB5
Level: Beginning
RIGHT-JUSTIFY OR LEFT-JUSTIFY TEXT
Use the Format$ function to produce right- or left-justified text:
Format$(123, "@@@@@@") gives " 123" Format$(123, "!@@@@@@") gives "123 "
-Rod Stephens, Boulder, Colorado
VB4 16/32, VB5
Level: Beginning
LEARN CONTROL ARRAY BOUNDS
You can use a control array's UBound and LBound properties to determine how many controls
are loaded. This code fills a string with the captions in the Label1 control array:
For i = Label1.LBound To Label1.UBound txt = txt & Label1(i).Caption & ", " Next i
-Rod Stephens, Boulder, Colorado
VB3, VB4 16/32, VB5
Level: Beginning
PERFORM ONE-TIME INITIALIZATION
You can use static variables to perform one-time initialization:
Private Sub GetValue() Static initialized As Boolean If Not initialized Then ' Perform one-time initialization. : initialized = True End If ' Do other stuff. : End Sub
-Rod Stephens, Boulder, Colorado
VB4 16/32, VB5
Level: Intermediate
CREATE GLOBAL PROPERTIES
You can create property procedures in a BAS module. The rest of your program treats the
"property" like any other variable, but the property procedures can perform
error checking and one-time initialization.
-Rod Stephens, Boulder, Colorado
VB4 16/32, VB5
Level: Intermediate
USE EXPLICIT OBJECT TYPES FOR SPEED
It is much faster to use explicit object data types instead of generic ones. In this test
that simply sets an object's public variable, the generic object takes more than 150 times
longer than the specific object:
Private Sub Command1_Click() Dim specific As MyClass Dim generic As Object Dim start_time As Single Dim stop_time As Single Dim i As Long Set specific = New MyClass Set generic = New MyClass start_time = Timer For i = 1 To 100000 specific.value = i Next i stop_time = Timer MsgBox Format$(stop_time - start_time) start_time = Timer For i = 1 To 100000 generic.value = i Next i stop_time = Timer MsgBox Format$(stop_time - start_time) End Sub
-Rod Stephens, Boulder, Colorado
VB3, VB4 16/32, VB5
Level: Advanced
MAKE A FORM STAY ON TOP
You can make a form always remain above others, even when it does not have focus. Use this
code in a BAS module:
#If Win16 Then Declare Sub SetWindowPos Lib "User" ( _ ByVal hWnd As Integer, _ ByVal hWndInsertAfter As Integer, _ ByVal X As Integer, ByVal Y As Integer, _ ByVal cx As Integer, ByVal cy As Integer, _ ByVal wFlags As Integer) #Else Declare Function SetWindowPos Lib _ "user32" (ByVal hwnd As Long, _ ByVal hWndInsertAfter As Long, _ ByVal x As Long, ByVal y As Long, _ ByVal cx As Long, ByVal cy As Long, _ ByVal wFlags As Long) As Long #End If Public Const SWP_NOMOVE = &H2 Public Const SWP_NOSIZE = &H1 Public Const HWND_TOPMOST = -1 Public Const HWND_NOTOPMOST = -2
Use this code to make the form stay on top in the form module:
SetWindowPos hwnd, HWND_TOPMOST, 0, 0, 0, 0, _ SWP_NOMOVE + SWP_NOSIZE
Use this code to make the form no longer stay on top in the form module:
SetWindowPos Parent.hwnd, HWND_NOTOPMOST, _ 0, 0, 0, 0, SWP_NOMOVE + SWP_NOSIZE
In 16-bit systems, use the 16-bit equivalents.
-Rod Stephens, Boulder, Colorado
VB3, VB4 16/32, VB5
Level: Intermediate
SET PRINTER MARGINS
You can use the Printer's scale properties to set margins. Set the properties so the
position (0, 0) is mapped to where you want the margins. This code makes the left margin
0.5 inch and the top margin 0.75 inch. The factor of 1440 converts inches into twips:
Printer.ScaleLeft = -0.75 * 1440 Printer.ScaleTop = -0.5 * 1440 Printer.CurrentX = 0 Printer.CurrentY = 0
-Rod Stephens, Boulder, Colorado
VB3, VB4 16/32, VB5
Level: Advanced
MOVE A FORM WITHOUT A TITLE BAR
Enter this code in a BAS module to let users move a window without a title bar:
Declare Function ReleaseCapture Lib "user32" () As Long Declare Function SendMessage Lib "user32" _ Alias "SendMessageA" ( _ ByVal hwnd As Long, ByVal wMsg As Long, _ ByVal wParam As Long, lParam As Any) As Long Public Const HTCAPTION = 2 Public Const WM_NCLBUTTONDOWN = &HA1
To give users a way to begin the move, place a little colored PictureBox in one corner of the form and let its MouseDown event begin the process:
Private Sub Picture1_MouseDown(Button As _ Integer, Shift As Integer, X As Single, Y As Single) ReleaseCapture SendMessage hwnd, WM_NCLBUTTONDOWN, HTCAPTION, 0& End Sub
-Rod Stephens, Boulder, Colorado
VB5
Level: Beginning
ENUMS IMPROVE READABILITY
An enumerated type is simply a list of constants, each of which has a unique value. An
Enum can improve the readability of your code by allowing you to declare a variable of
your enumerated type, then assign one of the elements of the Enum to the value of the
variable. Visual Basic makes this easy by providing you with a list of values for your
variable as you use it:
Public Enum TimeOfDay Morning = 0 Afternoon = 1 Evening = 2 End Enum Sub Main() Dim RightNow As TimeOfDay If Time >= #12:00:00 AM# And Time < #12:00:00 PM# Then RightNow = Morning ElseIf Time >= #12:00:00 PM# And Time < #6:00:00 PM# Then RightNow = Afternoon ElseIf Time >= #6:00:00 PM# Then RightNow = Evening End If End Sub
Validity checking is not done when assigning values to the special-typed variable. Even though the TimeOfDay values range from zero to two, VB doesn't attempt to keep you from assigning a value of four, or another number, to such a variable. Be especially aware of this when writing Property Let procedures, which accept an enumerated parameter.
-Charles Caison, Greensboro, North Carolina
VB3, VB4 16/32, VB5, VBA, VBS
Level: Intermediate
IMPROVE PERFORMANCE BY ELIMINATING SUBEXPRESSIONS
Arrays can reduce the amount of code you must write to perform an operation, especially
when used with a loop. By using the same array element in multiple places in your code,
you can increase the speed with which your code executes if you resolve the array only
once. This code determines if the value of the array element is this value, or if the
value of the array element is that value:
If intArray(intArrayIndex) = 5 or _ intArray(intArrayIndex) = 10 Then
Because Visual Basic must calculate the location of the array element to resolve its value (base + intArrayIndex * sizeof_intArray_type), it makes sense that the code executes faster the less the calculation is performed. This code provides a faster implementation:
TheValue = intArray(intArrayIndex) If TheValue = 5 or TheValue = 10 Then
This technique offers performance gains that are even more dramatic when used in a loop:
For intArrayIndex = 0 to 10 TheValue = intArray(intArrayIndex) If TheValue = 5 or TheValue = 10 Then ' Do something here End If Next
By eliminating the redundant subexpression and assigning the value to the variable named "TheValue" only once per loop (executes 10 times) instead of twice per loop (executes 20 times), you significantly reduce the amount of work that VB must perform to complete this loop.
-Charles Caison, Greensboro, North Carolina
VB3, VB4 16/32, VB5, VBA
Level: Intermediate
SIMPLIFY VARIABLE DECLARATIONS BY USING DEFAULT TYPES
Hungarian notation and similar naming schemes tell you at a glance the data type of any
variable in your code. You know that the variable intCounter is an integer, and you know
that strName is a string.
You can simplify your variable declarations by telling VB that any variable you declare
that begins with a certain letter will always be a certain type. This relieves you of
having to include the AS DataType clause in your variable declarations, but you can still
take advantage of the benefits of explicit variable type declaration. This code informs VB
that all variables beginning with the letter "i" will be integers:
DefInt i Dim iCounter
If you use the Visual Basic function TypeName() and pass it the variable iCounter, it returns "Integer" rather than "Variant." In addition to specifying a specific character, you can also specify a range or list of letters. This code assigns variables that begin with the letters i, j, or k as integers, and those variables that begin with s or c as strings:
DefStr s, c DefInt i-k Dim iCounter ' an integer Dim sName ' a string
Here are more default variable type declarations:
DefBool (Boolean) DefByte (Byte) DefLng (Long) DefCur (Currency) DefSng (Single) DefDbl (Double) DefDec (Decimal) DefDate (Date) DefStr (String) DefObj (Object) DefVar (Variant)
-Charles Caison, Greensboro, North Carolina
VB3, VB4 16/32, VB5, VBA, VBS
Level: Intermediate
MAINTAIN USERNAME AND PASSWORD
Due to a minor bug, the Internet Transfer Control cannot use the username and password
properties if they are set before the URL property. Because of this, you should always set
the URL property first. This code will fail:
Inet1.Password = "Chicken_Feet" Inet1.UserName = "JohnnyW" Inet1.URL = FTP://ftp.32X.com Inet1.Text = Inet1.OpenURL
This code, however, should work properly:
Inet1.URL = FTP://ftp.32X.com Inet1.Password = "Chicken_Feet" Inet1.UserName = "JohnnyW" Inet1.Text = Inet1.OpenURL
The first section of code fails because the URL is set after the username and password are set. The second section of code works because the URL is set first.
-Charles Casion, Greensboro, North Carolina
VB3, VB4 16/32, VB5
Level: Beginning
VB VERSION ISDATE DIFFERENCES
Under VB3, IsDate returns True only if the string corresponds to the date format indicated
by the "Regional" or "International" settings in the Control Panel.
Under VB4 and VB5, however, IsDate returns True if the date is a valid date in any format
(mm/dd/yy or dd/mm/yy).
There are two morals to this story. First, if your VB3 apps claim that dates are invalid
when they look correct, check the Control Panel settings. Second, if you need to enforce a
particular date format in your VB4 and VB5 programs, you need to take steps beyond using
IsDate. For example, you can use masked-edit controls or extra code to validate date
formats.
-Jon Pulsipher, Plano, Texas
VB3, VB4 16/32, VB5
Level: Intermediate
SIMULATE WIN95 TASKBAR WITHIN YOUR APP
The Windows 95 taskbar (with the Auto Hide check box set) is quite attractive and provides
a compact, nonintrusive way to access and organize information. You can easily simulate
this functionality in a VB program and provide a useful alternative to a pull-down menu
and/or SpeedButton. To set up such a "taskbar" in your VB application, include a
control that can act as a container for other controls in your VB form. The PictureBox
control looks good and works well; or you can use a Panel or a Frame.
Set the PictureBox's Align and AutoSize properties. The Align property indicates where the
taskbar will reside on the form, and the AutoSize property ensures that the PictureBox is
sized to fit the contours of its parent form whenever the form is resized.
Set the PictureBox's Visible property to False. Make sure your custom taskbar is not
visible until the mouse is moved over a defined "hot" zone on the form. A
"hot" zone is a location on the screen defined in X or Y coordinates. You can
use these coordinates in any unit of measurement, such as twips or pixels. Set the Parent
form's ScaleMode property to the unit of measurement you wish to work in.
Set the Width and/or Height of the PictureBox to appropriately show embedded controls or
information. Set up code in the Form's MouseMove event to handle the taskbar. This code
aligns the taskbar to the left of the screen:
'Object Property Setting '------ -------- ------- 'Form Name FrmTaskBarEx ' ScaleMode Pixel 'PictureBox Name PicTaskBar ' Align Align Left ' AutoSize True ' Visible False Private Sub Form_Load() ' Set Width of PictureBox to 1/4 size of Parent form ' when form is loaded. This is wide enough to show ' all of the controls I embedded in the PictureBox, ' and will vary with each application. PicTaskBar.Width = Me.ScaleWidth / 4 End Sub Private Sub Form_MouseMove(Button As _ Integer, Shift As Integer, X As Single, Y As Single) ' When the horizontal mouse position is less ' than or equal to defined hot zone ' (in this case, horizontal pixel position 4), show taskbar If (X <= 4) Then PicTaskBar.Visible = True ' When the horizontal mouse position is ' greater than the width of the ' PictureBox, hide taskbar ElseIf (X > PicTaskBar.Width) Then PicTaskBar.Visible = False End If End Sub
-Pete Rodriguez, Jersey City, New Jersey
VB4 16/32, VB5
Level: Beginning
LET THE EDITOR CHECK YOUR SPELLING
To make certain that you declared your variables, place Option Explicit in your
Declarations section. Using a mixture of upper and lower case in variable names, you can
easily verify that you don't misspell variable names as you type them. By entering the
names in all lower or upper case, the editor changes the variables' appearance
automatically to match the declared syntax:
Public strFetchThis as String Public iCountMe as Integer
When you declare these variables, typing STRFETCHTHIS or icountme results in the editor's changing them to the declared appearance when you move on.
-Randall Arnold, Coppell, Texas
VB3, VB4 16/32, VB5, VBA
Level: Intermediate
DETERMINE NEXT/PREVIOUS WEEKDAY
This function returns week identifier information, such as Week Beginning/Ending date, and
makes it more generic to return a date of any previous or following weekday. You can use
this function in VB5 and VBA5; with minor modifications to the optional arguments, you can
also use it in VB3 and VB4:
Public Function SpecificWeekday(d As Date, _
Optional ByVal WhatDay As Byte = _
vbSaturday, Optional ByVal GetNext _
As Boolean = True) As Date
'Purpose: Returns a date of the
'Next/Previous specific weekday for a given date
' Input: d - Date for which next/previous
' weekday is needed
' WhatDay - optional (byte)
' argument (default = vbSaturday)
' specifying what weekday to find
' GetNext - optional (Boolean)
' argument: True for
' Next(default), False for Previous
'Output: Date of the next/previous specific weekday
'Note: If both optional arguments are
' omitted, returns Week-Ending Date
' If passed date (d) falls on the
' same weekday as WhatDay, the
' function returns the passed date
' unchanged.
Dim iAdd As Integer
iAdd = (WhatDay - WeekDay(d))
If GetNext Then
SpecificWeekday = DateAdd("d", IIf(_
iAdd >= 0, iAdd, 7 + iAdd), d)
Else
SpecificWeekday = DateAdd("d", IIf(_
iAdd <= 0, iAdd, iAdd - 7), d)
End If
End Function
-Serge Natanov, received by e-mail
VB3, VB4, VB5, VBA, VBS
Level: Intermediate
FIND TROUBLE SPOTS
Implement a low-tech trace of your application by writing a message whenever your code
enters and exits a subroutine. This can help you locate elusive bugs, because you can turn
on the trace and run your application until failure. The last entry in your log indicates
what subroutine you were executing when the failure occurred. Enter this code in the
General Declarations section of a module:
Public DebugMode as Boolean
Normally, you should set this variable to False. During debugging, however, set it to True (DebugMode = True). Place this sub in the module:
Public Sub WriteDebugMessage(ByVal Msg as String) If DebugMode then 'write a message, including the system time End If End Sub
Enter this code as the first statement in every subroutine and function in your project:
Call WriteDebugMessage("Entering NameOfSubroutine")
Enter this code as the last statement in every subroutine and function:
Call WriteDebugMessage("Exiting NameOfSubroutine")
VB4 introduced conditional compilation, which offers a simpler way to implement this scheme. By defining a conditional compiler constant rather than a global flag variable, you can optimize your final EXE by toggling the constant to False. Conditional calls to the WriteDebugMessage routine won't be compiled into your shipping build:
#Const DebugMode = False
' for final code, true to test
#If DebugMode Then
Call WriteDebugMessage("Important Info")
#End If
Use this code to write other debug information to the log, such as variable values. Don't forget to turn off Debug mode when you're not using it to avoid writing massive amounts of unneeded data to the log.
-Shannon Huggins, Lancaster, South Carolina
VB4 16/32, VB5
Level: Beginning
USE ARRAYS, NOT COLLECTIONS
Arrays take less memory and are faster than collections. If you don't need to use a
collection's keyed lookup, easy extensibility, and other features, use an array instead.
-Rod Stephens, Boulder, Colorado
VB3, VB4 16/32, VB5, VBA, VBS
Level: Beginning
DRAW COMPLEX SHAPES
You can create complex shapes easily if you have a copy of Microsoft PowerPoint,
CorelDraw, or any other graphics editor. Using your graphic editor's drawing tools, draw
the shape you want in the presentation document. PowerPoint features a wide range of
drawing tools and autoshapes that let you combine a variety of basic shapes and styles
into complex images that you can fill, shade, or rotate to any angle.
When you're satisfied with your complex shape, choose Select from the Edit menu, and Copy
from the Edit menu in PowerPoint. You can also save the image as a Windows metafile from
packages that support that option. Switch tasks to your VB IDE, add an Image control to
the active form, and paste the metafile that was copied from PowerPoint into the Image.
When you want to draw the stored shape in your running VB application, assign the metafile
from the Image control to the destination drawing object:
picDraw.Picture = imgMetafile.Picture
Use drag-and-drop to copy the image from the source control to the drop target control. All scaling and drawing is handled automatically. You don't need to set the ScaleMode property of your destination object. You can use this technique when you want to decorate forms with complex shapes or create a Balloon Help form, a process control modeling application in which the images represent the elements of the production flow, or a flow-chart application.
-Rob Parsons, Dee Why, New South Wales, Australia
VB3, VB4 16/32, VB5
Level: Beginning
PASS PARAMETERS TO USER DIALOGS
It's fairly common practice to add buttons to your date and numeric fields to allow users
to select and display a popup calendar or calculator. However, to display a calculator or
calendar without allowing it to communicate with the calling application defeats the
purpose of giving the user these capabilities. The called dialog is only an appendage that
cannot pass the user's calculation back to the field from which the resource was called.
To solve this problem, add a button to a form next to a numeric input field (txtAmount).
In the Click event of this button, place a Load statement for the form you want to show
the user:
Sub cmd_Click() Load Calculator_Dialog Calculator_Dialog.Show 1 ' modal End Sub
Pass parameters to a form by writing a wrapper utility that handles the passing of these parameters to and from the called dialog:
Sub cmd_Click() CalculatorDialog_Show txtAmount End Sub Sub CalculatorDialog_Show (C As Control) '' Display the Calculator_Dialog and return '' the calculated value as a string Load Calculator_Dialog Calculator_Dialog.lblReadout = _ Format(Val(C.Text), "#.###############") ' Pass the number to dialog Calculator_Dialog.Op1 = Format(Val(C.Text), _ "#.###############") ' simulate user input Calculator_Dialog.LastInput = "NUMS" Calculator_Dialog.Show 1 ' modal If Calculator_Dialog.Action = True Then C.Text = Format(Calculator_Dialog._ lblReadout, "General Number") End If Unload Calculator_Dialog Set Calculator_Dialog = Nothing End Sub
The parameters are passed to hidden label controls on the Calculator_Dialog form
between the time the form is loaded and the time it's displayed. A hidden label control on
the Calculator_Dialog (Action) indicates whether the user chose the OK or Cancel button to
exit the dialog. Rather than unload the Calculator_Dialog when the user presses the OK or
Cancel button, the form hides until the calling sub (CalculatorDialog_Show) processes the
value of Calculator_Dialog.lblReadout. The form is then unloaded, and the Set-to-Nothing
statement is executed to purge memory of the form's controls and procedures.
This technique works with any version of VB. Starting with VB4, you can add properties and
methods to forms, which is a preferable method to relying on hidden labels for interobject
communication.
-Rob Parsons, Dee Why, New South Wales, Australia
VB3, VB4 16/32, VB5
Level: Intermediate
LET THE USER CONTROL LONG OPERATIONS
To allow the user to control long operations, use a single CommandButton to control
starting and stopping a looping process:
Dim Running As Boolean Private Sub CmdStartStop_Click() If Running Then ' Stop the process. Running = False CmdStartStop.Caption = "Start" CmdStartStop.Enabled = False Else ' Start the process. Running = True CmdStartStop.Caption = "Stop" RunLongProcess CmdStartStop.Enabled = True End If End Sub Private Sub RunLongProcess() Do While Running ' Do something repeatedly. : DoEvents Loop End Sub
-Rod Stephens, Boulder, Colorado
VB3, VB4 16/32, VB5
Level: Beginning
A QUICK EXPLORER-LIKE INTERFACE
Although the new VB5 Application Wizard can build a shell application with an
Explorer-like interface, it is often desirable to drop a quick Explorer form into your
code without the toolbar or the extra code included by the wizard. You can use only three
controls to create a form quickly with the Explorer split-panel look and feel.
To get an Explorer interface up and running, drop a picture box onto a form and set the
BorderStyle property to zero (none). Add two controls to the picture box. These controls
will represent the left and right panels. Drop in this code:
Private Sub Form_Resize() ' Optionally, resize manually if you don't ' want container to cover entire form and ' resize with form. Picture1.Move 0, 0, Me.ScaleWidth, Me.ScaleHeight End Sub Private Sub Picture1_Resize() Dim offset As Integer Static percent As Single offset = 4 * Screen.TwipsPerPixelX If percent = 0 Then percent = 0.5 Else percent = (Text1.Width + offset) / _ Picture1.Width End If Text1.Top = 0 Text1.Left = 0 Text1.Width = Picture1.Width * percent - offset Text1.Height = Picture1.Height Text2.Top = 0 Text2.Left = Text1.Width + offset Text2.Width = Picture1.Width - Text2.Left Text2.Height = Picture1.Height End Sub Private Sub Picture1_MouseMove(Button As _ Integer, Shift As Integer, X As Single, _ Y As Single) Dim offset As Integer, pwidth As Integer offset = 2 * Screen.TwipsPerPixelX pwidth = Picture1.Width If Button = vbLeftButton And X > 20 * _ offset And X < pwidth - 20 * offset Then Text1.Width = X - offset ElseIf X < 20 * offset Then Text1.Width = 19 * offset ElseIf X > pwidth - 20 * offset Then Text1.Width = pwidth - 19 * offset End If Text2.Left = Text1.Width + 2 * offset Text2.Width = pwidth - Text2.Left End Sub
In this example, I used two multiline text boxes with scrollbars, but TreeView and ListView controls work just as well.
-David Grantier, Atlanta, Georgia
VB5
Level: Intermediate
TRICK SETUP WIZARD
Don't you hate that VB5's Setup Wizard doesn't include all the files you reference in your
application? For example, if you access a picture or animation file at run time using
syntax such as Animation1.Open App.Path & "\MyVideo.AVI", VB5's Setup Wizard
doesn't include this file in its setup list.
To make VB5's Setup Wizard include files in the setup automatically, you can declare a
fictional API procedure in the Declarations section of any module that references the file
within a conditional compilation construct:
#If False Then Private Declare Sub Foo Lib "VIDEO.AVI" () 'Fake Declare #End If
Because the condition is False, Visual Basic ignores this statement. However, the Setup Wizard interprets this line as a function declaration, locates the file (in this case, VIDEO.AVI), and includes it in the setup list. Setup Wizard will default to placing these files in your App folder, so change it accordingly.
-Miguel Santos, Aveiro, Portugal
VB3, VB4 16/32, VB5
Level: Beginning
READ AND WRITE ARRAYS QUICKLY
You can read and write arrays quickly from files using Put and Get. This approach is
faster than reading and writing the array one entry at a time:
Dim arr(1 To 100000) As Long Dim fnum As Integer fnum = FreeFile Open "C:\Temp\xxx.dat" For Binary As fnum Put #fnum, , arr Close fnum
-Rod Stephens, Boulder, Colorado
VB3, VB4 16/32, VB5
Level: Intermediate
PRINT GRAY LINES AND AREAS
Black and white printers cannot print gray lines, but they can dither to create gray
areas. To create a gray border around an area, draw thin gray boxes with DrawStyle =
vbInvisible (5) so they have no borders.
-Rod Stephens, Boulder, Colorado
VB4 16/32, VB5
Level: Intermediate
DETERMINE IF YOUR PROGRAM IS RUNNING WITHIN VB'S IDE
Sometimes it is useful to know if your program is running within Visual Basic's Integrated
Development Environment (IDE) or as a standalone EXE. This routine returns True if the
program is running within VB's IDE:
Public Function RunningInIDE() As Boolean 'Assume running as EXE for now RunningInIDE = False 'Trap errors On Error GoTo RunningInIDEErr 'Divide by zero (fails within IDE) Debug.Print 1 / 0 'Exit if no error Exit Function RunningInIDEErr: 'We get error if Debug.Print was 'evaluated (i.e. running in the VB IDE) RunningInIDE = True End Function
RunningInIDE performs a division by zero in a Debug.Print statement. Within the IDE, this causes a divide overflow, which the function traps in an error handler. When the program is run as a standalone EXE, Debug.Print statements are not evaluated and no error occurs.
-Jeffrey Sahol, Greensboro, North Carolina
VB4 16/32, VB5
Level: Intermediate
EXTRA DLLS AS A RESULT OF CONDITIONAL COMPILATION
Starting with Visual Basic 4.0, you can add conditional compilation statements and use
them to create different versions for 16-bit and 32-bit environments or to call debugging
DLLs while testing your applications. However, you have to be careful when you use the
setup wizard to generate the installation package because those files will be included
unless you remove them from the distribution list. It is even worse when 16-bit code is
upgraded to VB5 because some of the 16-bit DLLs are no longer included in the operating
system, such as USER.DLL. In this case, you have to comment out all the references to
these libraries.
-Gerardo Villeda, Drexel Hill, Pennsylvania
VB3, VB4 16/32, VB5
Level: Intermediate
SPEED UP SELECTING ITEMS IN A MULTISELECT LIST BOX
Try this routine to select or deselect all items in a list box. Add a list box to your
form with the MultiSelect property set to Simple or Extended, and add items to the list
box:
Sub ToggleSelectAll (lst As ListBox, ByVal bState As Integer) Dim i As Integer lst.Visible = False 'Avoid redraws for each item For i = 0 To (lst.ListCount - 1) lst.Selected(i) = bState Next i lst.Visible = True End Sub
This routine sets the list box's Visible property to False to prevent the list box from repainting itself after each item is selected. This makes the routine more efficient. However, you can speed up this routine by using SendMessage instead of VB statements:
Sub ToggleSelectAll (lst As ListBox, _ ByVal bState As Integer) Dim i As Integer Dim nRet As Long lst.Visible = False For i = 0 To lst.ListCount - 1 nRet = SendMessage(lst.hWnd, LB_SETSEL, bState, i) Next i lst.Visible = True End Sub
You can speed up this routine significantly by taking advantage of the fact that the LB_SETSEL message sets the state of all items in the list box at once if the index argument is -1. Because this approach uses a single call to SendMessage, you don't need to worry about setting the list box's Visible property to False to prevent multiple redraws:
Sub ToggleSelectAll (lst As ListBox, _ ByVal bState As Integer) Dim nRet As Long nRet = SendMessage(lst.hWnd, LB_SETSEL, bState, -1) End Sub
Use these 16-bit declarations:
Declare Function SendMessage Lib "User" ( _ ByVal hWnd As Integer, ByVal wMsg As Integer, _ ByVal wParam As Integer, ByVal lParam As Long) As Long Global Const WM_USER = &H400 Global Const LB_SETSEL = (WM_USER + 6)
Or use these 32-bit declarations:
Public Declare Function SendMessage Lib _ "User32" Alias "SendMessageA" ( _ ByVal hWnd As Long, ByVal wMsg As Integer, _ ByVal wParam As Long, ByVal lParam As Long) As Long Public Const WM_USER = &H400 Public Const LB_SETSEL = (WM_USER + 6)
-Garold Minkin, Brooklyn, New York
VB4 32, VB5
Level: Beginning
MODIFY A TOOLBAR'S IMAGE LIST CONTROL
Have you ever tried to create tools on a toolbar using an image list, only to find that
you must detach the toolbar from the list and reset all the toolbar button properties
every time you want to add to the image list? Annoying, isn't it?
Before adding anything to the image list, cut the toolbar object. Then you can revise the
image list with no complaints from the IDE. Provided that you retain all the original
image indexes, you can paste the toolbar object back on the form and retain the toolbar's
link to the image list.
-David J. Schraff, Cleveland, Ohio
VB4 32, VB5
Level: Intermediate
EASILY CREATE ALL DIRECTORIES IN A PATH
Use this code to create a tree of folders on Windows 95 or NT 4.0 in one line:
Private Declare Function _ MakeSureDirectoryPathExists Lib "IMAGEHLP.DLL" _ (ByVal DirPath As String) As Long Private Sub Command1_Click() Dim MyPath As String Dim bResult As Long 'Specify the directory that we need MyPath = "C:\Win95\Temp\MyFolder\" & _ "MyFolder\Fld1\Fld2\" 'Now create that directory if it does exist. 'The entire path will be created if needed bResult = MakeSureDirectoryPathExists(MyPath) 'Test for failure If bResult = 0 Then MsgBox "MakeSureDirectoryPathExists failed!" End If End Sub
-Mordechai Eli, received by e-mail
VB4 16/32, VB5
Level: Intermediate
IMPLEMENT A BINARY TREE
A binary search tree can be useful when you have to traverse a lot of data in sorted
order. As this CBinarySearchTree class demonstrates, you can implement binary search trees
easily using objects and recursion (both data recursion and procedural recursion):
'class properties: Private LeftBranch As CBinarySearchTree Private RightBranch As CBinarySearchTree Private NodeData As String 'Adds a new value to the binary tree Public Sub AddNode(NewData As String) If Len(NodeData) = 0 Then 'Store data in current node if empty NodeData = NewData ElseIf NewData < NodeData Then 'Store data in left branch if NewData < NodeData If LeftBranch Is Nothing Then Set LeftBranch = New CBinarySearchTree End If LeftBranch.AddNode NewData Else 'Store data in right branch if NewData '>= NodeData If RightBranch Is Nothing Then Set RightBranch = New CBinarySearchTree End If RightBranch.AddNode NewData End If End Sub 'Displays all values in this tree 'If called on a child node, displays all 'values in this branch Public Sub TraverseTree() 'Traverse left branch If Not LeftBranch Is Nothing Then LeftBranch.TraverseTree End If 'Display this node MsgBox NodeData 'Traverse right branch If Not RightBranch Is Nothing Then RightBranch.TraverseTree End If End Sub
Test this class by creating a new CBinarySearchTree object, calling AddNode a few times to store data, and then calling TraverseTree to see the results. Binary search trees don't get much simpler than this.
-David Doknjas, Surrey, British Columbia, Canada
VB3, VB4 16/32, VB5
Level: Advanced
USE TOOLBAR-STYLE TITLE BARS
To make a form use a small toolbar-style title bar, set the form's WS_EX_TOOLWINDOW
extended style:
Declare Function GetWindowLong Lib "user32" _ Alias "GetWindowLongA" ( _ ByVal hwnd As Long, _ ByVal nIndex As Long) As Long Declare Function SetWindowLong Lib "user32" _ Alias "SetWindowLongA" ( _ ByVal hwnd As Long, _ ByVal nIndex As Long, _ ByVal dwNewLong As Long) As Long Public Const WS_EX_TOOLWINDOW = &H80& Public Const GWL_EXSTYLE = (-20) Declare Function SetWindowPos Lib "user32" ( _ ByVal hwnd As Long, _ ByVal hWndInsertAfter As Long, _ ByVal x As Long, ByVal y As Long, _ ByVal cx As Long, ByVal cy As Long, _ ByVal wFlags As Long) As Long Public Const SWP_FRAMECHANGED = &H20 Public Const SWP_NOMOVE = &H2 Public Const SWP_NOZORDER = &H4 Public Const SWP_NOSIZE = &H1 Private Sub Form_Load() Dim old_style As Long old_style = GetWindowLong(hwnd, GWL_EXSTYLE) old_style = SetWindowLong(hwnd, _ GWL_EXSTYLE, old_style Or _ WS_EX_TOOLWINDOW) SetWindowPos hwnd, 0, 0, 0, 0, 0, _ SWP_FRAMECHANGED Or SWP_NOMOVE Or _ SWP_NOZORDER Or SWP_NOSIZE End Sub
-Rod Stephens, Boulder, Colorado
VB4 32, VB5
Level: Intermediate
USE UNC NAMES TO REFER TO NETWORK DRIVES
If you write programs that access information on a network server, you never want to
hard-code drive letters. Not all software vendors take advantage of the Uniform Naming
Convention (UNC) (for example, \\SERVER\VOLUME\ ) technology. Use these API declarations:
Public Declare Function GetVolumeInformation _ Lib "kernel32" Alias "GetVolumeInformationA" ( _ ByVal lpRootPathName As String, _ ByVal lpVolumeNameBuffer As String, _ ByVal nVolumeNameSize As Long, _ lpVolumeSerialNumber As Long, _ lpMaximumComponentLength As Long, _ lpFileSystemFlags As Long, _ ByVal lpFileSystemNameBuffer As String, _ ByVal nFileSystemNameSize As Long) As Long Public Function GetNetworkDrive(FileSystem _ As String, VolumeName As String) As String 'Returns the first mapped drive letter 'if successful or "NODRIVE" if fails. 'FileSystem and SysName refer to the 'Network file system type: 'NWCOMPA => Novell 'NTFS => Microsoft 'FAT => Local\Microsoft Dim SerialNum As Long, SysFlags As Long Dim retVal As Long, Complength As Long Dim VolBuff As String * 255, SysName As String * 255 Dim DrivePath As String Dim i As Integer GetNetworkDrive = "NODRIVE" For i = 70 To 90 DrivePath = Chr(i) & ":\" retVal = GetVolumeInformation _ (DrivePath, VolBuff, 255, _ SerialNum, Complength, SysFlags, SysName, 255) If (Mid$(VolBuff, 1, Len(VolumeName)) _ = UCase$(VolumeName)) And(Mid$(SysName,1, Len _ (FileSystem)) = FileSystem) Then GetNetworkDrive = DrivePath Exit For End If Next i End Function
Here's the wrong and right ways to refer to network drives:
Option Explicit
Public Sub OpenDatabase()
'The Wrong Way!
Dim filespec as String
filespec = "H:\PUBLIC\APPS\BTRIEVE\MYDB.RDB"
'Some third-party control that opens the
'database file.
...
...
...
End Sub
Public Sub OpenDatabase()
'A Better Way!
Dim filespec as String
Dim Vol1Drive As String
Vol1Drive = GetNetworkDrive("NWCOMPA","VOL1")
If Vol1Drive = "NODRIVE" Then
MsgBox "Unable to open database. " & _
"The user does not have a " & _
"drive letter mapped to VOL1"
Else
filespec = Vol1Drive & _
"\PUBLIC\APPS\BTRIEVE\MYDB.RDB"
'Some third-party control that opens
'the database file.
...
...
...
End If
End Sub
-Charles Douglas, New Orleans, Louisiana
VB4 32, VB5
Level: Intermediate
SUSPEND CODE WHILE WAITING FOR SHELLED PROCESS
This "wait" routine suspends your code and waits for the shelled process to
finish. It comes in handy when you need to run another script\batch file during your
process. Use this calling syntax:
Private sub cmdPrint_Click() WaitForProcessToEnd "C:\PLOTTER.BAT" 'Let the user know when the process is finished. MsgBox "The process is finished! " End Sub
Here are the API declarations:
Public Const INFINITE = -1& Public Declare Function WaitForSingleObject _ Lib "kernel32" (ByVal hHandle As Long, _ ByVal dwMilliseconds As Long) As Long Public Declare Function OpenProcess Lib _ "kernel32" (ByVal dwAccess As Long, _ ByVal fInherit As Integer, _ ByVal hObject As Long) As Long Public Sub WaitForProcessToEnd(cmdLine As String) 'You can substitute a discrete time 'value in milliseconds for INFINITE. Dim retVal As Long, pID As Long, pHandle _ As Long pID = Shell(cmdLine) pHandle = OpenProcess(&H100000, True, pID) retVal = WaitForSingleObject(pHandle, INFINITE) End Sub
-Charles Douglas, New Orleans, Louisiana
VB4 32
Level: Advanced
MORE TIPS FOR "CREATING A BETTER MOUSE TRAP"
I would like to add a few things to the "Building a Better Mouse Trap" tip [VBPJ
November 1996, page 56]. This approach also works for any message, including button-up and
button-down messages. Windows 95 calls the appropriate function and passes the mouse
coordinates and other information in lParam and wParam, which, in the case of the
MouseMove event, VB converts to the Button, Shift, X, and Y arguments. If the user clicks
on the icon in the system tray, Windows passes 513 and 514 (WM_LBUTTONDOWN and
WM_LBUTTONUP) to VB, and VB performs a conversion that leaves the original mouse message
in X. If ScaleMode of the invisible form, frmOmni in the example, is left as Twips, this
tip won't work for every system. To make this tip work on every system, set ScaleMode of
the invisible form to Pixels.
-Goran Stijacic, San Diego, California
VB4 32, VB5
Level: Advanced
CREATE A GLOBALLY UNIQUE IDENTIFIER (GUID)
I use this routine in almost every application I develop. It's handy whether you need a
key for a collection or whether you use it in a database:
Option Explicit Private Declare Function CoCreateGuid Lib _ "OLE32.DLL" (pGuid As GUID) As Long Private Declare Function StringFromGUID2 Lib _ "OLE32.DLL" (pGuid As GUID, _ ByVal PointerToString As Long, _ ByVal MaxLength As Long) As Long ' Private members Private Const GUID_OK As Long = 0 Private Type GUID Guid1 As Long Guid2 As Integer Guid3 As Integer Guid4(0 To 7) As Byte End Type Public Function CreateGUIDKey() As String '*** Possible max length for buffer Const GUID_LENGTH As Long = 38 Dim udtGUID As GUID 'User Defined Type Dim strFormattedGUID As String 'The formatted string Dim lngResult As Long 'Useless result flag '*** Create a 'raw' GUID lngResult = CoCreateGuid(udtGUID) If lngResult = GUID_OK Then '*** Pre-allocate space for the ID strFormattedGUID = String$(GUID_LENGTH, 0) '*** Convert the 'raw' GUID to a 'formatted string StringFromGUID2 udtGUID, _ StrPtr(strFormattedGUID), GUID_LENGTH + 1 Else '*** Return nothing or handle error strFormattedGUID = "" End If ' *** Return our nicely formatted GUID CreateGUIDKey = strFormattedGUID End Function
-Doug Olson, Eden Prairie, Minnesota
VB4 32, VB5
Level: Advanced
SEND MESSAGES TO WINPOPUP FROM YOUR APPLICATION
If you have an application that must run "unattended" and you want it to alert
you if something goes wrong, your application can send you a message through WinPopUp.
WinPopUp uses a mail slot to communicate with other computers in the network. Choose a
mail slot name, such as \\computername \mailslot\messngr, and use this code:
Option Explicit Private Declare Function CloseHandle Lib _ "kernel32" (ByVal hHandle As Long) As Long Private Declare Function WriteFile Lib _ "kernel32" (ByVal hFileName As Long, _ ByVal lpBuff As Any, _ ByVal nNrBytesToWrite As Long, _ lpNrOfBytesWritten As Long, _ ByVal lpOverlapped As Long) As Long Private Declare Function CreateFile Lib _ "kernel32" Alias "CreateFileA" ( _ ByVal lpFileName As String, _ ByVal dwAccess As Long, _ ByVal dwShare As Long, _ ByVal lpSecurityAttrib As Long, _ ByVal dwCreationDisp As Long, _ ByVal dwAttributes As Long, _ ByVal hTemplateFile As Long) As Long Private Const OPEN_EXISTING = 3 Private Const GENERIC_READ = &H80000000 Private Const GENERIC_WRITE = &H40000000 Private Const GENERIC_EXECUTE = &H20000000 Private Const GENERIC_ALL = &H10000000 Private Const INVALID_HANDLE_VALUE = -1 Private Const FILE_SHARE_READ = &H1 Private Const FILE_SHARE_WRITE = &H2 Private Const FILE_ATTRIBUTE_NORMAL = &H80 Function SendToWinPopUp(PopFrom As String, _ PopTo As String, MsgText As String) As Long ' parms: PopFrom: user or computer that ' sends the message ' PopTo: computer that receives the ' message ' MsgText: the text of the message ' to send Dim rc As Long Dim mshandle As Long Dim msgtxt As String Dim byteswritten As Long Dim mailslotname As String ' name of the mailslot mailslotname = "\\" + PopTo + _ "\mailslot\messngr" msgtxt = PopFrom + Chr(0) + PopTo + Chr(0) + _ MsgText + Chr(0) mshandle = CreateFile(mailslotname, _ GENERIC_WRITE, FILE_SHARE_READ, 0, _ OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0) rc = WriteFile(mshandle, msgtxt, _ Len(msgtxt), byteswritten, 0) rc = CloseHandle(mshandle) End Function
-Mauro Mariz, Trento, Italy
VB4 16/32, VB5
Level: Beginning
FILL A LIST BOX WITH THE VALUES FROM A DATABASE TABLE
Use this code to fill a list box with the values from a database table. The first field in
the query provides the ItemData for the list:
Call FillList(dbase, "select personno, " & _ "personname from tblperson order by " & _ "personname;", lstperson) Sub FillList(thedb As Database, thesql As _ String, THELIST As Control) On Error Resume Next THELIST.Clear Call FillListAp(thedb, thesql, THELIST) End Sub Sub FillListAp(thedb As Database, thesql As _ String, THELIST As Control) On Error Resume Next Dim theset As Recordset Dim inlist As String Dim I As Integer Set theset = thedb.OpenRecordset(thesql, _ dbOpenSnapshot) While Not theset.EOF For I = 1 To theset.Fields.Count - 1 If I = 1 Then If IsNull(theset.Fields(I)) Then inlist = "Null" Else inlist = theset.Fields(I) End If Else If IsNull(theset.Fields(I)) Then inlist = inlist & Chr(9) & "Null" Else inlist = inlist & Chr(9) & _ theset.Fields(I) End If End If Next I THELIST.AddItem inlist THELIST.ItemData(THELIST.NewIndex) = _ theset.Fields(0) theset.MoveNext Wend theset.Close End Sub
-Tim Miller, received by e-mail
VB3, VB4 16/32, VB5
Level: Intermediate
MAKE SURE DATA IS SAFE BEFORE UNLOADING
To decide when it is safe to exit your program, use a DataUnsafe function. Set the
DataModified variable to False when you load or save data, or when you start a new file.
Set DataModified to "OK" to remove the current data:
Dim DataModified As Boolean
Private Function DataUnsafe() As Boolean
If DataModified Then
Select Case MsgBox _
("Save changes to the data?", vbYesNoCancel)
Case vbYes
' Save the data. SaveData should
' set DataModifed False if successful.
SaveData
DataUnsafe = DataModified
Case vbNo
' OK to clear data.
DataUnsafe = False
Case vbCancel
' Cancel operation and keep data.
DataUnsafe = True
End Select
Else
' The data is not modified.
DataUnsafe = False
End If
End Function
Private Sub Form_Unload(Cancel As Integer)
Cancel = DataUnsafe()
End Sub
-Rod Stephens, Boulder, Colorado
VB3, VB4 16/32, VB5
Level: Beginning
CONVERT FROM FRACTIONAL TO DECIMAL NUMBERS
While developing a database front end for hand-tool management, I discovered a need to
handle both fractional and decimal representations of dimensions in the same text box.
This makes it easier on users who worked from a variety of prints to input part feature
sizes. To accomplish this, place this function in the LostFocus event of any text box that
can receive numerical input. You can also cycle through the appropriate text boxes and run
the function against the text value of each. In addition, this function only checks for
the inches character (double quotes) at the end of the text string of fractional
dimensions. It also looks for spaces and/or dashes between whole numbers and fractions and
checks for both forward and backward slashes within fractions. It doesn't work with
negative values:
Private Function ReturnDecimalValue(Size As _ String) As String Dim strSize As String Dim iGap As Integer Dim iSlash As Integer Dim sWhole As Single If Size <> "" Then Size = LTrim(RTrim(Size)) 'previous code may have stripped text to nothing 'if it was just spaces, so test If Size <> "" Then 'strip off inch character (double 'quotes) if it's there If Right(Size, 1) = Chr$(34) Then _ Size = Left(Size, Len(Size) - 1) iGap = InStr(Size, "-") If iGap = 0 Then iGap = InStr(Size, " ") If iGap Then sWhole = CSng(Left(Size, iGap - 1)) strSize = Right(Size, Len(Size) - iGap) iSlash = InStr(strSize, "/") 'user may have input backward slash 'in fraction instead of forward slash; 'verify If iSlash = 0 Then iSlash = InStr(strSize, "\") 'convert result to decimal form for 'saving in database If iSlash Then Size = CStr(sWhole + _ (CSng(Left(strSize, iSlash - 1)) / _ CSng(Right(strSize, Len(strSize) - iSlash)))) End If ReturnDecimalValue = Size End Function
-Randall Arnold, Coppell, Texas
VB3, VB4 16/32, VB5
Level: Intermediate
SEED THE RANDOM NUMBER GENERATOR
You can use Rnd followed by Randomize to seed Visual Basic's random number generator.
Whenever you use the same seed, Rnd produces the same sequence of random numbers:
Rnd -1 Randomize seed
-Rod Stephens, Boulder, Colorado
VB4 16/32, VB5
Level: Beginning
BETTER AUTO-PROPERCASE
The "Auto-Propercase Text Box at Entry" tip [VBPJ May 1997, page 63] has a
simpler solution. The StrConv function can propercase any string. You can achieve the same
effect with this code in the KeyUp event of a text box:
Private Sub Text1_KeyUp(KeyCode As Integer, _ Shift As Integer) Dim iCurPos As Integer iCurPos = Text1.SelStart Text1.Text = StrConv(Text1, vbProperCase) Text1.SelStart = iCurPos End Sub
-Manish Garg, Bloomington, Minnesota
VB3, VB4 16/32, VB5
Level: Intermediate
AVOID FORM CONFUSION
When you define a form named MyForm, Visual Basic creates one instance with the name
"MyForm." Many programmers confuse this special instance with other instances
created using Dim. For example, the Caption statement in this code sets the caption on the
automatically created instance. When the instance FRM appears, its caption is not set:
Dim frm As New MyForm MyForm.Caption = "This is the single instance" frm.Show
Even more confusing problems can arise if you use MyForm within the MyForm code module, when an instance such as FRM might accidentally set properties on the automatically created form rather than itself. For this reason, never use MyForm within the MyForm code module.
-Rod Stephens, Boulder, Colorado
VB3, VB4 16/32, VB5
Level: Beginning
READ-ONLY TEXT CONTROLS WITHOUT THE CARET
Assume you want a text control with a vertical scrollbar, but you don't want users to be
able to modify it and you don't want users to see any caret in the control when they click
on it. However, you still want users to be able to scroll all text.
Here is the solution. First, put a Text1 control and a Command1 control on Form1. Change
the Text1 control property to Locked = True. Change the Text1 control property to
MousePointer = 1 - Arrow. Change the Text1 control property to ScrollBars = 2 - Vertical,
and enter this code:
'code in Form1 Private Sub Form_Load() 'make Command1 control disappear when the form shows Command1.Left = -2000 End Sub 'code in Text1 control Private Sub Text1_GotFocus() 'move the focus to somewhere else Command1.SetFocus End Sub
-Jian Wang, Woodside, New York
VB3, VB4 16/32, VB5
Level: Beginning
SWITCH TO ANOTHER APP AND CLOSE IT
Use the built-in AppActivate command to switch to another application easily if you know
its title. You can even close the application programmatically:
'This will close app
Private Sub CloseApp (AppTitle As String)
On Error GoTo ErrExit
AppActivate AppTitle
SendKeys "%{F4}", True
ErrExit:
End Sub
-Ketan Patel, Lansing, Michigan
VB3, VB4 16/32, VB5
Level: Intermediate
SHOW 3-D TEXT MESSAGES
If you want to print text on an object with 3-D effects, use this subroutine to convert
fonts into 3-D fonts with borders. In this routine, the user can define shadow length,
shadow color, font color, border color, and position of text on the object. Note that all
color values are in the range of 0-15 because they are used as arguments for the QBColor
function:
Sub Fonts3d(Print_Object As Object, Text1 As _ String, postx As Single, Posty As _ Single, Shadow_Length As Integer, _ FontsColor As Integer, ShadowColor As _ Integer, BorderColor As Integer) Dim I As Integer, Prev_Scale_Mode As Integer Prev_Scale_Mode = Print_Object.ScaleMode If postx = -1 Then 'for center align postx = (Print_Object.ScaleWidth - _ Print_Object.TextWidth(Text1)) / 2 End If Print_Object.ForeColor = QBColor(ShadowColor) 'Generate shadow For I = 1 To Shadow_Length * 16 Step 8 Call PrintText(Print_Object, _ postx + I, Posty + I, Text1) Next I 'Print border Print_Object.ForeColor = QBColor(BorderColor) Call PrintText(Print_Object, postx - 15, Posty, Text1) Call PrintText(Print_Object, postx + 15, Posty, Text1) Call PrintText(Print_Object, postx, Posty - 15, Text1) Call PrintText(Print_Object, postx, Posty + 15, Text1) Print_Object.ForeColor = QBColor(FontsColor) Call PrintText(Print_Object, postx, Posty, Text1) End Sub Sub PrintText(Print_Object As Object, _ Xposition As Single, Yposition As _ Single, Text1 As String) Print_Object.CurrentX = Xposition Print_Object.CurrentY = Yposition 'Print text on object Print_Object.Print Text1 End Sub ' example of usage: Call Fonts3d(Picture1, "WELCOME TO T.T.T.I.", _ 50, 150, 5, 6, 11, 12)
-Atmabodh Hande, Shamla Hills, Bhopal, India
VB5
Level: Beginning
ADD RIGHT-CLICK FUNCTIONALITY
By default, the right-click functionality needed for What's This? Help is not available in
VB. Selecting a menu command from a context menu created for the button lets you display
the What's This? Help topic when the user right-clicks on a command button. First, set the
WhatsThisHelp property of the form to True. Place a CommandButton control on the form.
Using the Menu Editor, create a menu with a top-level invisible item named
mnuBtnContextMenu, and a submenu named mnuBtnWhatsThis with a caption of "What's
This?". Finally, place this code in the MouseUp event of the command button:
Private ThisControl As Control Private Sub Command1_MouseUp(Button As _ Integer, Shift As Integer, X As Single, Y As Single) If Button = vbRightButton Then Set ThisControl = Command1 PopupMenu mnuBtnContextMenu End If Set ThisControl = Nothing End Sub Private Sub mnuBtnWhatsThis_Click() ThisControl.ShowWhatsThis End Sub
-Blue Sky Software Technical Support
VB5
Level: Beginning
ADD THE "?" BUTTON TO A FORM
The WhatsThisButton property returns or sets a value that determines whether the
WhatsThisButton appears in the title bar of a Form object during run time. For the
WhatsThisButton to appear on your form, set the WhatsThisButton and WhatsThisHelp
properties to True; the ControlBox property to True; the BorderStyle property to Fixed
Single or Sizable; and the MinButton and MaxButton properties to False, or the BorderStyle
property to Fixed Dialog.
-Blue Sky Software Technical Support
VB4 16/32, VB5
Level: Advanced
PROVIDE PRINT PREVIEW
You can provide Print Preview at different scales. First, make your printing routine take
on the object it should draw as a parameter. Then, for printing, pass the routine the
Printer object. For preview, pass the routine a hidden PictureBox. Then use PaintPicture
to copy the hidden picture to a visible PictureBox at the desired scale. Drawing at full
scale on the hidden PictureBox allows you to scale fonts and other graphics without
distortion.
-Rod Stephens, Boulder, Colorado
VB3, VB4 16/32, VB5
Level: Intermediate
FASTER SEARCHES ON ARRAYS, LIST BOXES, AND COMBO BOXES
This method is handy when the user enters data that you need to validate against a lookup
table. Validating the value by querying the database is out of the question because of the
relatively slow response time. An alternative is to keep the lookup table locally in a
sorted array, or in a list-box or a combo-box control whose Sorted property is set to
True. Lookup tables are static, so you don't need to worry about the local copy being out
of sync with the database. For large sorted arrays of strings or for list-box or combo-box
controls with large sorted lists (in the range of 10,000 entries), you will find the
binary search to be 10 to 20 times faster than calling the API, and hundreds of times
faster than a sequential search. The difference becomes dramatic if the operation needs to
be done multiple times. If you want to use an array instead of a combo-box or a list-box
control, there is no API call you can use. Use this code for an array:
'In: 'Array to search Dim rasArray() As String 'String to search for Dim vsName As String 'Out: 'Index in the array of the string if found Dim rlIndex As Long 'Local variables: 'Index in the array Dim lnIdx As Long 'Lower bound of the search interval Dim lnMin As Long 'Upper bound of the search interval Dim lnMax As Long 'Return an invalid index, if string is not found rlIndex = LBound(rasArray) - 1 lnMax = UBound(rasArray) lnMin = LBound(rasArray) 'lookup vsName in rasArray() Do While lnMin <= lnMax lnIdx = (lnMax + lnMin) \ 2 If vsName = rasArray(lnIdx) Then rlIndex = lnIdx Exit Do ElseIf vsName < rasArray(lnIdx) Then lnMax = lnIdx - 1 Else lnMin = lnIdx + 1 End If Loop
You can easily modify this code for a combo-box control to use with list-box controls as well:
'In: 'Combo to search ' (change into As ListBox for listbox controls ' or use As Controls to use with both types ' of controls) Dim rcboCombo As ComboBox 'String to search for Dim vsName As String 'Out: 'Index in the combo if the string is found Dim rlIndex As Long 'Local variables 'Index in the array Dim lnIdx As Long 'Lower bound of the search interval Dim lnMin As Long 'Upper bound of the search interval Dim lnMax As Long 'Return an invalid index, if string is not found rlIndex = -1 lnMin = 0 lnMax = rcboCombo.ListCount - 1 lnIdx = lnMax \ 2 'lookup name in the combo Do While rlIndex = -1 And lnMin <= lnMax If vsName = rcboCombo.List(lnIdx) Then rlIndex = lnIdx ElseIf vsName < rcboCombo.List(lnIdx) Then lnMax = lnIdx - 1 lnIdx = (lnMax + lnMin) \ 2 Else lnMin = lnIdx + 1 lnIdx = (lnMax + lnMin) \ 2 End If Loop
-Adrian Cerchia, received by e-mail
VB3, VB4 16/32, VB5
Level: Intermediate
COMPRESS SHORT STRINGS INTO A LONG VALUE
When developing relational database applications, you often need to use list boxes or
combo boxes to store records with alphanumeric keys. You can load numeric keys into the
ItemData array of combo boxes and list boxes as Long integers. Programmers traditionally
store alphanumeric keys in a String array with the index of the array elements stored in
ItemData. However, for four-character, alphanumeric keys, avoid the overhead of an array
by using CodeCrypt to convert the key into a Long integer.
CodeCrypt accepts a variant and returns a variant. If a four-character string is received,
then CodeCrypt converts it to a Long integer. Each character, in turn, is converted to its
ASCII value. The value in CodeCrypt is multiplied by 256 to shift the current value left
by one byte. The ASCII value is then added to CodeCrypt (filling the empty low-order
byte). Because a Long integer is made up of 32 bits (four bytes), up to four characters
can now be stored in ItemData. If CodeCrypt receives a Long integer, the process is
reversed and a string is returned:
Function CodeCrypt(pvInput As Variant) As Variant Dim i As Integer, temp As Long If UCase(TypeName(pvInput)) = "LONG" Then temp = pvInput Do While temp > 0 CodeCrypt = Chr$(temp Mod 256) & CodeCrypt temp = CLng(temp / 256) Loop Else If Len(pvInput) > 4 Then Exit Function For i = 1 To Len(pvInput) CodeCrypt = CodeCrypt * 256 + _ Asc(UCase$(Mid$(pvInput, i, 1))) Next i End If End Function
Use this code to add alphanumeric code to lstBox.ItemData:
lstBox.AddItem text lstBox.ItemData(lstBox.NewIndex) = CodeCrypt(code)
Use this code to get alphanumeric code back from lstBox.ItemData:
sCode = CodeCrypt(lstBox.ItemData(lstBox.ListIndex))
This routine is unable to deal with strings whose first character is greater than Chr$(127).
-Matthew B. Butler and Steve Hochreiter, San Angelo, Texas
VB5
Level: Intermediate
SORT DATA IN THE SHORT DATE FORMAT
Suppose you have a database field that returns a date in the Short Date format. Neither a
numeric sort nor a string sort would order this column correctly. To sort by date, you
need to add an extra column to the grid and set its width to zero. Populate the column
with values obtained by converting the date to a number, and sort on that column as
demonstrated here (this code assumes the date field is in column 2):
Dim Ro As Integer Dim SortCol As Integer Dim SortDate As Double 'add a column to hold the sort key MSFlexGrid1.Cols = MSFlexGrid1.Cols + 1 SortCol = MSFlexGrid1.Cols - 1 MSFlexGrid1.ColWidth(SortCol) = 0 'invisible 'calculate key values & populate grid For Ro = 1 To MSFlexGrid1.Rows - 1 SortDate = DateValue(MSFlexGrid1.TextMatrix(Ro, 2)) MSFlexGrid1.TextMatrix(Ro, SortCol) = SortDate Next Ro 'do the sort MSFlexGrid1.Col = SortCol 'set the key MSFlexGrid1.Sort = flexSortNumericAscending
-VideoSoft Tech Support
VB4 16/32
Level: Intermediate
PROGRESS BARS WITH A GRADIENT
The tip "Color Status Indicator" ["101 Tech Tips for VB Developers,"
Supplement to the February 1997 issue of VBPJ, page 26] got me thinking that it would look
even more attractive to have the status change color in gradient steps. Instead of
changing the color at particular points, start at red, blend to orange, then yellow, and
finally green.
To try this, place a Sheridan 3-D panel on your form and set the FloodType property to 1
(Left to Right) and ShowFloodPct to False. Place a command button and a text box (set the
Caption to blank) on the form to do your testing. Place this code in the form:
Private Sub Command1_Click() Dim i As Integer, iIncrement As Integer Dim iMidPoint As Integer, iCheckpoint As Integer Dim j As Integer, sAddIncrement As String Dim sSubIncrement As String iIterations = Val(Text1) iMidPoint = iIterations * 0.5 - 1 ' find the midpoint If iIterations / 510 = iIterations \ 510 Then 'perfect algorithm iIncrement = 1 iCheckpoint = 1 ElseIf iIterations < 510 Then 'increment the color faster iIncrement = 510 \ iIterations iCheckpoint = 1 Else 'change the color less frequently iIncrement = 1 iCheckpoint = iIterations \ 510 + 1 End If sAddIncrement = "&H0000" & _ Format$(iIncrement, "00") & "00" sSubIncrement = "&H0000" & _ Format$(iIncrement, "0000") SSPanel1.FloodColor = &HFF 'start the panel at Red 'At your preference show the 'percentage. However, the tighter 'the loop, the less valuable this is. SSPanel1.FloodShowPct = True For i = 0 To iIterations - 1 'do your real processing here If i / iCheckpoint = i \ iCheckpoint Then With SSPanel1 If i <= iMidPoint Then .FloodColor = _ .FloodColor + sAddIncrement Else .FloodColor = _ .FloodColor - sSubIncrement End If .FloodPercent = (i + 1) / iIterations * 100 End With End If 'if the loop is tight, be sure to 'release the processor 'occasionally - also, some flood 'controls (other than SSPanel) 'may require this to get the 'color updated in the control DoEvents Next MsgBox "All done!", vbOKOnly + vbInformation SSPanel1.FloodPercent = 0 SSPanel1.FloodShowPct = False End Sub
The effect works best when your video is set to at least 16-bit (High Color). Because there are exactly 510 progressive gradients between red and green, the number of iterations you enter will influence what shade of green you end up with. As the iterations increase (>900), you'll end up with bright green.
-Jim Poland, Cedar Rapids, Iowa
VB3, VB4 16/32, VB5
Level: Intermediate
ADD USER PROPERTIES TO CONTROLS
To add user-defined properties to controls, use this code to store them in the control's
tag. You can define multiple additional properties at design or run time. You can easily
retrieve the value stored:
Control.Tag = AddParam((Control.Tag), _ "tooltip", "Close this window.") Control.Tag = AddParam((Control.Tag), "user", "True") Tooltip = GetParam((Control.Tag), "tooltip") Function AddParam (Text As String, _ Param As String, Value) As String Dim Text1 As String If Not IsNull(GetParam(Text, Param)) Then Text1 = DelParam(Text, Param) Else Text1 = Text End If If Text1 <> "" Then Text1 = Text1 & ";" End If AddParam = Text1 & Param & "=" & (Value) End Function Function DelParam (Text As String, _ Param As String) As String Dim i As Integer Dim j As Integer Dim s1 As String Dim s2 As String Dim Text1 As String Text1 = Text i = InStr(UCase(Text), UCase(Param) & "=") If i > 0 Then If i = 1 Then s1 = "" Else s1 = Left(Text, i - 2) End If j = InStr(i, Text, ";") If j > 0 Then s2 = Mid(Text, j + 1) Else s2 = "" End If If s1 = "" Or s2 = "" Then Text1 = s1 & s2 Else Text1 = s1 & ";" & s2 End If End If DelParam = Text1 End Function Function GetParam (Text, Param) Dim i As Integer Dim j As Integer Dim Text1 As String If Len(Text) Then If Left(Text, 1) <> "'" Then Text1 = ";" & Text & ";" i = InStr(LCase(Text1), ";" _ & LCase(Param) & "=") + 1 If i > 1 Then j = InStr(i + Len(Param), Text1, ";") GetParam = Mid(Text1, i + Len(Param) + 1, _ j - i - Len(Param) - 1) Else GetParam = Null End If Else GetParam = Null End If Else GetParam = Null End If End Function
-Dean Genner, North Sydney, Australia
VB4 16/32, VB5
Level: Beginning
JUMP BACK AND FORTH AMONG PROCEDURES QUICKLY
My code often has a lot of nested procedure calls, which can be painful to trace while
doing walk-throughs. Developers might be unaware of the "Procedure Definition"
(Shift+F2) feature, which provides a way to go to the code of a called procedure. This is
particularly convenient if you like to keep your hands on the keyboard as much as
possible.
Simply place the cursor on the procedure call, and press Shift+F2 to get to the
procedure's code. When you're done, Ctrl+Shift+F2 takes you back.
-Aseem Pitamber, Haryana, India
VB3, VB4 16/32, VB5
Level: Intermediate
USE VB SYSTEM COLOR CONSTANTS IN API CALLS
Visual Basic includes constants, such as vbActiveTitleBar and vbButtonFace, for Windows
system colors, which the user might change through the Control Panel. (In VB3, these
constants are defined in the file CONSTANT.TXT.) When you assign one of these constants to
a VB color property, Visual Basic automatically translates it to the actual color the user
has chosen for that item. You cannot, however, use VB's system color constants directly
with API functions, such as SetPixel, that expect a color as one of their parameters.
VB's system color constants are the same as those defined by the Windows API, except that
VB's constants have the high bit set. You can use this function to translate both VB and
Windows system color constants into the corresponding RGB color value, suitable for use in
API calls:
' 32-bit Option Explicit Declare Function GetSysColor Lib "User32" ( _ ByVal nIndex As Long) As Long Public Function SysColor2RGB(ByVal lColor As Long) As Long lColor = lColor And (Not &H80000000) SysColor2RGB = GetSysColor(lColor) End Function
For 16-bit versions of VB, replace the GetSysColor declaration with this code:
Declare Function GetSysColor Lib "User" ( _ ByVal nIndex As Integer) As Long
-Steve Cisco, Perrysburg, Ohio
VB3, VB4 16/32, VB5
Level: Beginning
CHANGE TOOLTIPS BACKGROUND COLOR
To change the ToolTips background color, open the Control Panel's Display tool. Click on
the Appearance tab. In the Item combo box, select ToolTip. Click on the little color box
to change the color.
-Rod Stephens, Boulder, Colorado
VB3, VB4 16/32, VB5
Level: Beginning
DOUBLING QUOTES FOR SQL STATEMENTS
This routine parses a string and returns an equivalent string where all the instances of a
given substring are doubled. This is especially useful for doubling quotes within SQL
statements to be passed to Access or other database engines that expect double quote marks
to represent a single quote mark:
Public Function DoubleString ( _ ByVal str As String, _ ByVal strDoubleString As String) As String Dim intStringLength As Integer Dim intDoubleStringLength As Integer Dim intPosition As Integer Dim strTemp As String intStringLength = Len(str) intDoubleStringLength = Len(strDoubleString) strTemp = str If intStringLength >= _ intDoubleStringLength And _ intDoubleStringLength > 0 Then intPosition = 1 Do While (intPosition > 0) And _ (intPosition <= intStringLength) intPosition = InStr(intPosition, _ strTemp, strDoubleString) If intPosition > 0 Then strTemp = Left(strTemp, _ intPosition - 1 + _ intDoubleStringLength) & _ strDoubleString & _ Mid(strTemp, intPosition + _ intDoubleStringLength, _ intStringLength) intStringLength = Len(strTemp) intPosition = intPosition + _ (intDoubleStringLength * 2) End If Loop End If DoubleString = strTemp End Function
-Eric Lynn, Ballwin, Missouri
VB4 32, VB5
Level: Intermediate
DRAW USERS' ATTENTION BY FLASHING WINDOWS' CAPTION
Do you want your programs to call users' attention? Use the API's FlashWindow function.
Put this code in a module:
Option Explicit Declare Function FlashWindow Lib "user32" ( _ ByVal hwnd As Long, ByVal bInvert As Long) As Long Sub Flash(hFlash As Long, iTimes As Integer, _ sInterval As Single) Dim i As Integer For i = 0 To iTimes 'iTimes sets the number of flashes Call FlashWindow(hFlash, True) Dim Start As Single Start = Timer ' Set start time. ' sInterval sets the time between flashes Do While Timer < Start + sInterval DoEvents ' Yield to other processes Loop Next i ' Puts everything back to normal Call FlashWindow(hFlash, False) End Sub
Add this code to a button:
Private Sub Command1_Click() 'Start the fun... Flash Me.hWnd, 20, 0.5 End Sub
-Iván Márquez, Miranda, Venezuela
VB5
Level: Beginning
USE PICTURES ON COMMAND BUTTONS
To use a picture on a CommandButton, you must set its Picture property and set its Style
to 1 - Graphical. Otherwise, the picture will be ignored.
-Rod Stephens, Boulder, Colorado
VB5
Level: Intermediate
PROVIDING AN "INSERT OBJECT" DIALOG FOR THE RICHTEXTBOX
One of the enhancements to the RichTextBox control in VB5 is the addition of an OLEObjects
collection, which allows Rich Text documents to include linked or embedded OLE objects.
However, the RichTextBox control provides no interactive way for users to insert such
objects; they must be added by means of the Add method of the OLEObjects collection.
You can, however, use the Insert Object dialog provided by VB's OLE Container control to
allow the user to insert an OLE object into a RichTextBox. Add an OLE Container control
(oleObj) to your form, and set its Visible property to False. Then add this code behind a
button or menu item:
Private Sub cmdInsertObject_Click() Dim sClass As String ' Show OLE Container control's ' Insert Object dialog oleObj.InsertObjDlg ' If user makes a selection, add it to ' RichTextBox's OLEObjects collection sClass = oleObj.Class If Len(sClass) Then rtfText.OLEObjects.Add , , , sClass ' Clear OLE Container's object to conserve memory oleObj.Class = "" End If End Sub
-Basil Hubbard, Hamilton, Ontario, Canada
VB3, VB4 16/32, VB5
Level: Beginning
RUN YOUR VB APP ON STARTUP
Do you have an application you need to launch on Windows startup? Typically, you do this
by placing an item in the Startup directory. However, you can also do this with a registry
entry. Add a new string value using the name of your application. The value is the path to
your executable:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\_ Windows\CurrentVersion\Run
A sample entry might look like this:
MyApp C:\Program Files\MyApp\MyApp.exe
-Kevin Gilchrist, Glendale, Arizona
VB5
Level: Beginning
CODE-COMMENTING SHORTCUTS
Instead of going to the Edit menu to comment out a section of code, you can add the
comment command to the shortcut menu you access by right-clicking in a code window. Select
View/Toolbars/Customize. On the Toolbars tab of the Customize dialog, click on the
"Shortcut Menus" check box. On the toolbar that pops up, click on Code
Windows... Code Window. On the Commands tab of the Customize dialog, select
"Edit" in the categories list box. Drag and drop "Comment Block" and
"Uncomment Block" from the "Commands list" box to the code window
menu. Hit the "Close" button on the Customize dialog. Now go to a code window,
drag the mouse over a section of code, right-click, and select "Comment code."
-Greg Ellis, St. Louis, Missouri
VB3, VB4 16/32, VB5, VBA
Level: Intermediate
IS MY OBJECT VALID?
Have you ever needed to determine if an object variable is holding a valid reference?
TypeName() returns a class name if the object holds a valid reference. It returns the word
"Nothing" if it does not:
Public Function IsObjValid(objTest As Object) As Boolean Dim vntResult As Variant vntResult = TypeName(objTest) If vntResult <> "Nothing" Then _ IsObjValid = TrueEnd Function
-Lee Taylor, Cornelius, North Carolina
VB3, VB4 16
Level: Advanced
CANCEL A PENDING PRINT JOB
In the tip, "Please Stop Printing!" ["101 Tech Tips for VB
Developers," Supplement to the August 1997 issue of VBPJ, page 13], the code works
fine with one exception. If you use PrintManager, anything printed before you press the
Abort button is sent to the printer. This code uses the Windows API AbortDoc to prevent
this. Put a button named cCancel on the form and caption it "Abort Printing."
Add this declaration to your program:
Declare Function AbortDoc% Lib "GDI" ( _ ByVal hDC As Integer)
Add this code to the cCancel button's Click event procedure:
Sub cCancel_Click () dim i% AbortPrintFlag=True On Local Error Resume Next i = AbortDoc(Printer.hDC) End Sub
Add this code to the print routine:
AbortPrintFlag=False Do While ...... Printer.Print ...... DoEvents If AbortPrintFlag then exit do Loop On Local Error resume next Printer.EndDoc
-Dennis E. Hining, Houston, Texas
VB3, VB4 16/32, VB5, VBA, VBS
Level: Beginning
CLEAN DRIED MARKS ON YOUR WHITE BOARD
If old words or marks have dried on a white board and you can't wipe them off, write on
top of them with a fresh pen and then rub them off. This also works if someone has used a
permanent pen.
-Rob Parsons, DeeWhy, New South Wales, Australia
VB4 32, VB5
Level: Intermediate
EXPORT SQL DATA TO A COMMA-SEPARATED VALUE FILE
Use this code to create a comma-separated value (CSV) file from a recordset based on a SQL
query. A number of applications, including Excel and Access, can read CSV files:
Function CSVExport(sSQL As String, sDest As _
String) As Boolean
On Error goto Err_Handler
Set snpExport = db.OpenRecordset(sSQL, dbOpenSnapshot)
Open App.Path & "\" & sDest For Output As #1
For iLoop = 0 To snpExport.Fields.Count _
- 1 'Export Field Names
sFieldText = "" & _
(snpExport.Fields(iLoop).Name)
Write #1, sFieldText;
Next
Write #1,
snpExport.MoveFirst
Do While snpExport.EOF = False
For iLoop = 0 To snpExport.Fields.Count - 1
sFieldText = "" & (snpExport.Fields(iLoop))
Write #1, sFieldText;
Next
Write #1,
snpExport.MoveNext
Loop
CSVExport = True
Exit Function
Err_Handler
MSGBOX("Error: " & Err.Description)
CSVExport=False
End Function
-Kevin O'Donnel, Mission Viejo, California
VB4 32, VB5
Level: Intermediate
CLOSE ALL OPEN RECORDSETS AND DATABASES
This small subroutine iterates through and closes all databases in the Databases
collection of the Workspaces object. For each database in the collection, it iterates
through each Recordset and closes it first:
Public Sub DBCloseAll() Dim DBInstance As Database Dim RSInstance As Recordset On Error Resume Next For Each DBInstance In Workspaces(0).Databases 'For all open databases.... For Each RSInstance In DBInstance.Recordsets 'For all open=20 Recordsets.... RSInstance.Close 'Close all Recordsets Next DBInstance.Close ' Close DB Next End Sub
-Marcus Cedergren, Gothenburg, Sweden
VB3, VB4 16/32, VB5
Level: Intermediate
RETRIEVE THE ID OF A NEWLY INSERTED DATABASE RECORD
The ID (counter field) of a newly inserted record is available immediately after the
AddNew method executes. Retrieving the ID at this point means you don't have to mess with
the LastModified property and bookmarks. You can clear the variable used to store the ID
if you cancel the update. Try this code from a button Click event:
With Data1.Recordset .AddNew MsgBox !ID .CancelUpdate End With
-Joe Maki, received by e-mail
VB4 16/32, VB5
Level: Beginning
RETURN TO A PREVIOUS LOCATION IN YOUR CODE
To return to a previous location in your code, press Ctrl+Shift+F2. This way you don't
need to set bookmarks. VB only keeps track of the last eight lines of code that you
accessed or edited. This feature is available in design time and in break mode.
-Trish Anders, Peoria, Arizona
VB3, VB4 16/32, VB5
Level: Beginning
A FAST WAY TO FIND ROUTINES
To quickly go to the code for a called function, subroutine, or property, simply place
your cursor on the called routine and hit Shift+F2. VB will immediately go to the routine
as long as it is defined in your project.
-Fred Meyer, Iowa City, Iowa
VB4 16/32, VB5
Level: Beginning
FORCE UPPERCASE CHARACTERS IN A TEXT BOX
To change text in a text box to uppercase as soon as the user types it in, use this code:
Private Sub txtname_KeyPress(KeyAscii As Integer) 'Puts in uppercase as soon as typed KeyAscii = Asc(UCase(Chr(KeyAscii))) End Sub
-Trish Anders, Peoria, Arizona
VB4 32, VB5
Level: Intermediate
ADD COLUMNS TO A STANDARD VB LIST BOX
Use the Win32 API to set tab stops in a Visual Basic list box by creating these
declarations and routine in a module:
Public Const LB_SETTABSTOPS = &H192 Declare Function SendMessage Lib "user32" _ Alias "SendMessageA" (ByVal hwnd As Long, _ ByVal wMsg As Long, ByVal wParam As Long, _ lParam As Any)As Long Sub SetListTabStops(iListHandle As Long) ' sets 2 tab stops in a list box at the 24th ' and 48th character ' iListHandle = the window handle of the list box Dim iNumColumns As Long Dim iListTabs(1) As Long Dim Ret As Long iNumColumns = 2 iListTabs(0) = 96 ' 96/4 = 24 characters iListTabs(1) = 192 ' 192/4 = 48 characters Ret = SendMessage(iListHandle, _ LB_SETTABSTOPS, iNumColumns, iListTabs(0)) End Sub
In your form, create a list box called lstMyListBox. Call this routine in the form load to set your tab stops:
Call SetListTabStops(lstMyListBox.hwnd)
Then add items to the list box using vbTab:
lstMyListBox.AddItem "Column 1 data" & _ vbTab & "Column 2 data"
-Catherine Spence, Hollis, New Hampshire
VB3, VB4 16/32, VB5
Level: Intermediate
PLACE A VARIABLE-LENGTH STRING IN TEXT
VB doesn't have a function to replace part of a string (of n-length) with another string
(of x-length). The Mid() statement works only with target and replacement strings of the
same length. Use this code to solve the problem:
Function ReplaceText( _ ByVal sOriginalString As String, _ ByVal sTargetString As String, _ ByVal sReplacement As String) As String Dim iOriginalLen As Integer Dim iTargetLen As Integer Dim iReplaceLen As Integer Dim iTargetLoc As Integer iOriginalLen = Len(sOriginalString) iTargetLen = Len(sTargetString) iReplaceLen = Len(sReplacement) If (iTargetLen = 0) Or (iOriginalLen = 0) Or _ (iReplaceLen = 0) Then ReplaceText = sOriginalString 'Improper use of function. Else iTargetLoc = InStr(sOriginalString, sTargetString) ReplaceText = Iif( iTargetLoc = 0, sOriginalString, _ Left(sOriginalString, iTargetLoc - _ 1) & sReplacement & Right( _ sOriginalString, iOriginalLen - _ iTargetLoc iTargetLen + 1) ) End If End Function
-Bruce Goldstein, Highlands Ranch, Colorado
VB3, VB4 16/32, VB5, VBA
Level: Beginning
PUT AN AMPERSAND (&) IN A MENU OR COMMAND BUTTON
When creating menus and command buttons, use the ampersand symbol to create a shortcut key
for that option. For example, you might use "&Cancel" for a command button
with a "Cancel" button used to cancel an event. To create menu options or
command buttons with an ampersand in the caption, set the Caption property (either by
coding or through the property settings form), using "&&" to place it in
the caption.
-James Kahl, St. Louis Park, Minnesota
VB4 32, VB5
Level: Advanced
REGISTER ACTIVEX COMPONENTS MANUALLY
Not all ActiveX DLL and OCX files include installation programs to properly register the
control. You need to run REGSVR32.EXE manually to perform the registration. You can save
time by creating a shortcut in your WINDOWS\SENDTO folder called "Register ActiveX
Control." Use the target name of C:\WINDOWS\REGSVR32.EXE for the shortcut. When you
have an ActiveX control you wish to register, right-click on the file name to display the
context menu, click on "Send To," and click on "Register ActiveX
Control." The RegSvr32 program will display a message box indicating the success or
failure of the registration.
-Tony Pappas, Calabasas, California
VB4 16/32, VB5
Level: Intermediate
DESTROYING COLLECTIONS' ITEMS
Many programmers mistakenly believe they can remove all the items from a collection by
setting the collection itself to Nothing:
Dim children as New Collection ... Set children = Nothing
This technique only works if you don't have another object variable pointing to the same collection. In this case, setting the children variable to Nothing doesn't destroy the collection; instead, it decreases its internal reference counter. The only way to remove all the items of the collection is with a loop of Remove methods:
Do While children.Count children.Remove 1 Loop
-Francesco Balena, Bari, Italy