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How to wait for a few seconds

Posted on 2003-02-28
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Last Modified: 2012-05-04

I am currently developing some software that waits for a couple (or more) seconds before continuing. I was using this:


While **check for seconds passed**
   DoEvents
Wend


This does the trick but works horrors to the poor little processor.

There must be a way to wait without processing anything, just waiting, simply wait.

I tried a couple of API calls but they killed the event processing so my programming 'dies' until the wait ends.

Any help will be appreciated.

Thanks.
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Question by:Esopo
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4 Comments
 
LVL 17

Accepted Solution

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inthedark earned 200 total points
ID: 8045919
To minimise affect on the processor you can do 2 things, use sleep and also calculate end time before loop. Example:

Const SecondsToTimeFactor As Double = 1#/(1440#*60#)

Dim TimeToStop As Date

DelaySeconds = 2 ' wait 2 seconds
TimeToStop = Now + (SecondsToTimerFactor * DelaySeconds)

Do While Now<TimeToStop
    Sleep 200 ' never sleep for more than 1 seconds (1000MS)
    DoEvents
Loop

You need this declaration:

Private Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Long)


Warning to not attempt to sleep for more than 1 seconds in a form.  This will cause a form to appear to hang.  If the form receives a windows message like close form/got/lost focus etc.  Messages will be queued until the function wakes up.
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LVL 17

Expert Comment

by:inthedark
ID: 8045948
I did some calculations and found that a program that waits in this way will use 1 seconds of CPU time every few weeks.
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LVL 14

Author Comment

by:Esopo
ID: 8046657


You are good!!!

I tried it out, it sure works!

I played with it a bit, and realizaed even a 1 ms sleep will release the processor to a point where it seems no extra processing is being done.

The thing is, I need the form to continue fully functional while waiting, and 200 ms makes it look like hanging while the user types on a textbox or something like it.

Anyway, this sleep idea works like a charm, I think you deserve an award for this.

PS: I can't believe how a simple 1 ms sleep can release the processor almost completely.

Best regards
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LVL 17

Expert Comment

by:inthedark
ID: 8047184
You should also checkout this link.  If you are not realy sleeping you should use the sleepex function.

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/winprog/winprog/functions_by_category.asp?frame=true
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