Structured Programming

You already know the best way to structure programs because you can use Microsoft’s Visual Basic design as a guide. The small event procedures you’ve seen and coded are perfect examples of the correct way to code. Don’t write long routines that do everything; instead, write small code procedures that each perform only one task, such as respond to a user’s keystroke. If the keystroke is to trigger a bunch of things, keep the event procedure small and call other small procedures that do the detailed work.

Structured programming is a programming method you use to break long programs into numerous small procedures, putting off the details as long as possible.

For example, suppose that you need to perform the following tasks when the user clicks a Reconcile command button in a checkbook application:

1. Display checks next to cleared items.

2. Total the cleared items.

3. Total the uncleared items.

4. Recommend an action if the manual checkbook balance and the checkbook computer file’s balance don't match.

5. Print a reconciliation report.

Such a detailed response to a single command button click would take many screens of code. Nevertheless, the Click() event procedure doesn't have to be many screens. Instead, you could insert a series of procedure calls that do the detailed work and keep the Click() procedure small like this:

Private Sub cmdReconcile_Click ()

Call ClearItems ()

Call UnClearItems ()

If ChkBkIsBalanced () Then

Call OutBalanceAction ()

End If

Call ReconcilePrint ()

End Sub

tip

You are now learning about a topic known as structured programming. In structured programming you delay coding details for as long as you can. Keep subdividing your code procedures so they simply control procedures that call more detailed procedures until you finally reach the point where a task cannot be further subdivided.

All the procedures called by a subroutine should be as small as possible and only perform a single task, or a series of calls to other procedures. When you follow this simple advice, your code becomes a structured, manageable set of routines where each subroutine performs a single task or controls other tasks.

Not only does structured programming make writing code easier, it makes managing code really simple. If your application contains a bug, you can more easily locate the bug because you follow the thread of procedures until you get to the routine that controls the logic with the bug. If your uncleared balance is incorrect, you can go directly to the procedure that computes that balance and then locate the problem without affecting lots of other code around that routine.

note

The called procedure is the procedure called by another procedure. The calling procedure is the procedure that triggers another’s execution.

Top Home