CIS 338: Control Arrays
Dr. Ralph D. Westfall
June, 2011
What Is a Control Array?
it is a group of controls:
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part of a collection in a .NET form
all identified as elements of Me.Controls
array
each has a different Index
 e.g., Me.Controls(0) , Me.Controls(1) etc.
Dropped From, Added To VB.NET
control arrays were in VB 6, but not in
earlier versions of .NET
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however you can set up controls in earlier
.NET code that work like VB6 control
arrays
link
link2
VB.NET Control Array Code
Dim i As Integer
For i = 0 To Me.Controls.Count – 1
MsgBox(Me.Controls(i).ToString)
Next
Following Slides Need Updating
Control Array Disadvantages
since all members use the same procedure, may
need more complicated logic to handle events
Private Sub Command1_Click(Index As _
Integer)
Select Case Index
Case 0
'user clicked cmdTest(0) button
Print "zero"
Case 1
'user clicked cmdTest(1) button
Print "one"
End Select
End Sub
Creating a Control Array (VB6)
create first control, and at the very first
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change the name
change any other properties that you want
to be the same on all elements e.g., Text
select it, then [Ctrl] C or Edit>Copy
[Ctrl] V or Edit>Paste to duplicate
click Yes on dialog box
move copied control where you want it
Programming Control Arrays
Dim nI as Integer
Private Sub Text1_Change(Index As Integer)
For nI = Text1.LBound To Text1.UBound
If nI = Index Then
Text1(nI).BackColor = "&H000000FF"
End If
Next nI
End Sub
• LBound is lowest Index in array (usually 0)
• UBound is highest Index in array
Using Parallel Arrays
Sub Text1_GotFocus(Index As Integer)
Label1(Index).Font.Bold = True
End Sub
• two arrays: Text1 and Label1
• when Text1(0) gets focus, Label1(0)
(same Index) becomes bold
• can use LostFocus event to remove bold
Adding Controls with Code
nI = Text1.UBound
Load Text1(nI + 1)
Text1(nI + 1).Visible = True
Text1(nI + 1).Top = _
Text1(nI).Top + _
Text1(nI).Height + 120
Text1(nI + 1).Left = _
Text1(nI).Left
Deleting Controls with Code
Private Sub Command2_Click()
Dim nI As Integer
nI = Text1.UBound
Unload Text1(nI)
End Sub
at run time, can only delete items
created by code (previous slide)
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can delete any items at design time
Advantages of a Control Array
more efficient – uses less memory
all members work with one procedure
to add controls to program when it is
running, must use control arrays
easier to change properties via code
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can use loops
gets around the limit of 254 control names
per form (but who needs that many??)