Control
Arrays: As
you have seen, arrays can have many data types. In addition to customary data types,
Visual Basic supports the concept of control arrays. You can think of this array
type as an array of objects, or in this case, an array of controls. Control
arrays support all types of Visual Basic controls.
To create a
control array in Visual Basic during design time, simply add a control to your
Form. Next, copy the control using either menu options or keyboard shortcuts,
and paste the copy in memory to the same Form. A dialog box should appear
asking whether you want to create a control array. After you select Yes in the
dialog box, the new control is added and your control array is created. After which,
you can continue to add controls to the array by pasting until you have the
desired amount.
When a control
becomes part of a control array, its name remains that of the control array,
with an element or index indicating its specific identity.
Set all
necessary control properties before making a control array. Otherwise, you will
have to set control properties for each control in the array.
Double-clicking
on any control in the array produces the same event. These shared events pass
an index as an argument that you can use to identify each control in the array:
Private
Sub Command1_Click(Index As Integer)
Command1(1).Caption
= “Index 1”
End
Sub
Beyond design
time, Visual Basic offers a more dynamic approach to control arrays in runtime.
During runtime, you can dynamically add controls and remove controls from a
control array. You add and remove these dynamic controls using the Load and
Unload statements:
Load
ObjectName(Index)
If you want to
load a control into a control array, you first must create the array in design
time.
When you unload
controls from a control array, the index must be a valid index; otherwise,
Visual Basic generates an error:
Unload
ObjectName(Index)
Why would you want an array of controls? Well,
in short, you might want an array ofcontrols for the same reason you would
want any other array, such as creating and maintaining less code or combining
like data (in this case, like controls). Beyond programming esthetics, control
arrays offer the benefit of shared procedures and events.
