Incremental timer - day hour minute second, how to make a very precise timer? Using GetLocalTime or GetSystemTime and substracting the days is not straight forward.

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LaHire

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What is the best way to make a time counter that increase every second; something displayed on a dialog box like DD HH:MM:SS (00 00:00:00 then 00 00:00:01 and so on)?

I thought about using WM_TIMER but I wonder if this timer is very accurate in long term (I mean for seconds it may be OK but as for days I do not know). So I was also thinking about using GetLocalTime or GetSystemTime but if I substract:
Actualtime.wDay - StartingDay.wDay
I may have a problem to calculate the delay between 2 days (day '1' - day '29' for instance) since months can have 28, 29, 30 or 31 days. In addition if someone for a reason or another change the time (or during an automatic change of hour) the result will not be good.

So if someone has a good suggestion or knows how to make a very precise* timer I am interested. Maybe WM_TIMER is good enough...

* : I mean after 10 days 00:00:00 it is really displayed 10 days 00:00:00.


akyprian
Administrator Group: Admins Posts: 2307 Member No.: 1 Joined: 12-May 04	Consider using QueryPerformanceCounter at application startup and QueryPerformanceCounter and QueryPerformanceFrequency API's in WM_TIMER. By this means, You would get a precise timer. I hope it helps

LaHire

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QUOTE (akyprian @ Feb 27 2008, 09:06 AM)

Consider using QueryPerformanceCounter at application startup and QueryPerformanceCounter and QueryPerformanceFrequency API's in WM_TIMER. By this means, You would get a precise timer.

I hope it helps

That is an idea. However "QueryPerformanceCounter" needs a hardware configuration (otherwise the function return 0).

From your experience did you try to use a WM_TIMER that increments (let's say every second) a counter for a long time and noticed a difference between its value and the time? This is just a question of accuracy.


akyprian
Administrator Group: Admins Posts: 2307 Member No.: 1 Joined: 12-May 04	I haven't tried WM_TIMER the way you ask, but I have observed that by other methods. In addition, from microsoft ...Because WM_TIMER messages are processed at a low priority, somewhat like WM_PAINT messages, they are often delayed while other messages are processed... Regards

Ratch

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LaHire,

QUOTE

What is the best way to make a time counter that increase every second; something displayed on a dialog box like DD HH:MM:SS (00 00:00:00 then 00 00:00:01 and so on)?

I think you are referring to a clock. Charles Petzold has two clock programs (digital and analog) in his book Programming Windows, Edition 5. His clocks do hours, min, and secs, but you should not have too much trouble modifying it. I am sending you the executable of the digital clock I transcribed into MASM. If you are interested in the MASM code I wrote, I can send it also. It uses the GetLocalTime API, which is as accurate as your CPU's time clock is. Ratch

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