Computer Programming Concepts and Visual Basic David I. Schneider

num(5) = 10
picOutput.Print Triple(num(5))
End Sub
Private Function Triple(x As Integer) As Integer
Triple = 3 * x
End Function
When the program is run and the command button clicked, 30 will be displayed.
3. Visual Basic provides two functions that simplify working with arrays that have
been passed to a procedure. If an array has been dimensioned with the range m
To n, then the values of the functions LBound(arrayName) and UBound(array-
Name) are m and n, respectively.
Private Sub cmdButton_Click()
Dim chiefJustice(13 To 15) As String
chiefJustice(13) = “Warren”
chiefJustice(14) = “Burger”
chiefJustice(15) = “Rehnquist”
Call Display(pres())
End Sub
Private Sub Display(a() As String)
Dim i As Integer
For i = LBound(a) To UBound(a)
picOutput.Print a(i) & “ ”;
Next i
End Sub
When the program is run and the command button clicked, “Warren Burger
Rehnquist” will be displayed.
6.3 CONTROL ARRAYS
We have seen many examples of the usefulness of subscripted variables. They are essential for
writing concise solutions to many programming problems. Because of the great utility that
subscripts provide, Visual Basic also provides a means of constructing arrays of text boxes, labels,
command buttons, and so on. Because text boxes, labels, and command buttons are referred
to generically in Visual Basic as controls, arrays of these objects are called control
arrays.
Unlike variable arrays, which can only be created by Dim and ReDim statements once a
program is running, at least one element of a control array must be created when the form is
designed. The remaining elements can be created either during form design, or, perhaps more
typically, with the Load statement when the program is run.
To create the first element of an array of text boxes, create an ordinary text box, then
access the Properties window, and select the property called Index. By default this property
is blank. Change the Index property to 0 (zero). Your text box is now the first element in a
subscripted control array. If the name of a text box is txtBox and its Index property is 0, then
assigning a value to the text box during run time requires a statement of the form
txtBox(0).Text = value
Arrays are not of much use if they contain only a single element. To create additional
elements of the txtBox( ) control array during form design, make sure that the element you
just created is active by clicking on it. Next, press Ctrl+C (or open the Edit menu and select
Copy). Visual Basic has now recorded all the properties associated with txtBox(0) and is
Control Arrays 179