1. Dr. Ralph D. Westfall June, 2011
CIS 338: Control Arrays
Dr. Ralph D. Westfall
June, 2011

2. What Is a Control Array? it is a group of controls:
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.

3. Dropped From, Added To VB.NET
control arrays were in VB 6, but not in earlier versions of .NET
however you can set up controls in earlier .NET code that work like VB6 control arrays
link
link2

4. VB.NET Control Array Code
Dim i As Integer
For i = 0 To Me.Controls.Count – 1
MsgBox(Me.Controls(i).ToString)
Next

5. Following Slides Need Updating

6. 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

7. Creating a Control Array (VB6)
create first control, and at the very first
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

8. 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

9. Using Parallel Arrays two arrays: Text1 and Label1
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

10. 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

11. 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)
can delete any items at design time

12. 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
can use loops
gets around the limit of 254 control names per form (but who needs that many??)