Bug Proofing Visual Basic: A Guide to Error Handling and Prevention
(Publisher: John Wiley & Sons, Inc.)
Author(s): Rod Stephens
ISBN: 0471323519
Publication Date: 11/01/98

Self-Test

Many of the ideas presented in this chapter cannot be easily demonstrated by example code. Pointing to a piece of code and saying it is the result of hasty work or too much emphasis on speed is difficult.

Program Bad1 violates several of the more easily demonstrated guidelines presented in this chapter. The program, shown in Figure 1.3, generates a random list of numbers. When you enter a value in the Target field and click the Search button, the program uses a binary search to locate the item you entered in the list.

The following code shows how program Bad1 works. Assume that this code has just been written near the beginning of the project, and that it has been accepted into the project’s code library. You should be able to make several improvements. Appendix A, “Self-Test Solutions,” contains a revised version of this code with some suggested changes.

Option Explicit

Private Values(1 To 50) As Integer

Private Sub Form_Load()
    Ready
End Sub

Private Sub Ready()
Dim i As Integer
Dim txt As String

    Randomize
    Values(1) = Int(Rnd * 10 + 1)
    For i = 2 To 50
        Values(i) = Values(i - 1) + Int(10 * Rnd + 1)
    Next i
    For i = 1 To 50
        txt = txt & Format$(i, “@@”) & _
            Format$(Values(i), “@@@@”) & vbCrLf
    Next i
    txtValues.Text = txt
End Sub

Private Sub CmdSearch_Click()
Dim i As Integer

    i = BinarySearch(Values, CInt(txtTarget.Text))
    lblPosition.Caption = Format$(i, “@@”) & _
            Format$(Values(i), “@@@@”) & vbCrLf
End Sub

Public Function BinarySearch(list() As Integer, _
    target As Integer) As Integer
Dim a As Integer
Dim b As Integer
Dim c As Integer

    a = 1
    c = 50
    Do While a <= c
        b = (c + a) / 2
        If target = list(b) Then
            BinarySearch = b
            Exit Function
        ElseIf target < list(b) Then
            c = b - 1
        Else
            a = b + 1
        End If
    Loop
    BinarySearch = 0
End Function

Summary

Mental discipline is critical for effective programming. The following Bug Stoppers summarize concepts that are helpful for maintaining a bug-free attitude. Attitude is everything. Without the proper mindset, you may write thousands of lines of code very quickly, only to waste months of extra time debugging them. By coding more carefully, you can produce more working code in less time. You can control the code and not let deadlines and bugs control you.

	BUG STOPPERS: Programming Philosophy
	Manage properly, even if you are the only developer.
	Fight bugs every step of the way.
	Catch bugs early.
	Stay in control.
	Intercept unnecessary work.
	Set consistent priorities.
	Change priorities as the project matures.
	Defer optimization.
	Don’t optimize unless necessary.
	Get it working first, then optimize if necessary.
	Be steady and thorough, not fast and sloppy.
	Code offensively to expose bugs, not hide them.
	Write for others, not for yourself.
	Write for people, not for the computer.
	Code for the ages.
	Code without attachment or ego.