[AccessD] Timer etc.

[Arthur Fuller]

A few messages ago, I asked for advice on resolving times. Gustav and JWC
(Colby) replied, and I got what I needed.

I'm teaching myself C++, and came across some code, which I decided to port
to VBA with modifications. The point of the exercise was to compare the
performance of a While Loop and a For/Next loop. On a small scale, the
differences are unnoticable, so I upped the iteration count to one million.
Then the difference is dramatic. The While test took 612 seconds; the
For/Next loop took 190 seconds.

In case anyone is interested, here is the code:

<code>
Option Explicit

Const CON_Limit = 1000000

Function WhileLoopTest()
    Dim i As Long
    i = 1
    Dim timStart As Long, timStop As Long
    timStart = Timer
    'Debug.Print timStart
    While i <= CON_Limit
        Debug.Print i
        i = i + 1
    Wend
    timStop = Timer
    'Debug.Print timStop
    'MsgBox "Elapsed time for " & CON_Limit & " iterations" & vbCrLf & _
    '    (timStop - timStart) & " seconds.", vbOKOnly, "While Test"
    WhileLoopTest = (timStop - timStart)
End Function

Function ForNextTest()
    Dim i As Long
    i = 1
    Dim timStart As Long, timStop As Long
    timStart = Timer
    'Debug.Print "Start: " & timStart
    For i = 1 To CON_Limit
        Debug.Print i
    Next
    timStop = Timer
    Debug.Print "Stop: " & timStop
    'MsgBox "Elapsed time for " & CON_Limit & " iterations" & vbCrLf & _
    '    (timStop - timStart) & " seconds.", vbOKOnly, "For/Next Test"
    ForNextTest = (timStop - timStart)

End Function

Sub DurationTest()
    MsgBox "This program compares While loops with For/Next loops",
vbOKOnly + vbInformation, _
    "Timing Test"
    Dim TimeW As Currency, TimeF As Currency
    TimeW = WhileLoopTest()
    TimeF = ForNextTest()
    MsgBox "Results of comparison for " & CON_Limit & " iterations:" &
vbCrLf & _
        "While Loop: " & TimeW & " seconds." & vbCrLf & _
        "For/Next  : " & TimeF & " seconds.", _
        vbOKOnly + vbInformation, _
        "While v. For/Next Comparison"
End Sub
</code>

-- 
Arthur