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Active Forums => QB64 Discussion => Topic started by: madscijr on February 23, 2022, 11:01:09 am

Title: how to time something (ie do loop for n seconds)
Post by: madscijr on February 23, 2022, 11:01:09 am
Thanks to @SMcNeill who taught me a little something:
"How do you time QB64 to do something for a certain amount of time?"

I thought maybe an example would come in handy for other QB64 newbies or users who haven't seen this.
(It certainly came in handy for me.)

Code: QB64: [Select]
  1.     ' DO SOMETHING FOR 3 SECONDS
  2.     t# = Timer + 3
  3.     Do
  4.         '(SOMETHING)
  5.     Loop Until Timer > t#

Original thread this came from, where Steve explains hardware images, which speed up graphics in QB64 big time:
https://qb64forum.alephc.xyz/index.php?topic=4674.0 (https://qb64forum.alephc.xyz/index.php?topic=4674.0)
Title: Re: how to time something (ie do loop for n seconds)
Post by: SMcNeill on February 23, 2022, 11:26:52 am
One caveat here:  You *can* experience bugs with this after midnight.

Program starts at 23:59:59.  Add three seconds -- 24:00:02...  (In seconds, and not hours and minutes like this, though hours and minutes are easier to visualize.)

Clock hits midnight:  0:00:00

At no point will you ever have TIMER become greater than t#.

If you're going to have a program which might run into this issue, I'd suggest just plugging in my ExtendedTimer and use it instead:

Code: QB64: [Select]
  1. FUNCTION ExtendedTimer##
  2.     d$ = DATE$
  3.     l = INSTR(d$, "-")
  4.     l1 = INSTR(l + 1, d$, "-")
  5.     m = VAL(LEFT$(d$, l))
  6.     d = VAL(MID$(d$, l + 1))
  7.     y = VAL(MID$(d$, l1 + 1)) - 1970
  8.     FOR i = 1 TO m
  9.         SELECT CASE i 'Add the number of days for each previous month passed
  10.             CASE 1: d = d 'January doestn't have any carry over days.
  11.             CASE 2, 4, 6, 8, 9, 11: d = d + 31
  12.             CASE 3: d = d + 28
  13.             CASE 5, 7, 10, 12: d = d + 30
  14.         END SELECT
  15.     NEXT
  16.     FOR i = 1 TO y
  17.         d = d + 365
  18.     NEXT
  19.     FOR i = 2 TO y STEP 4
  20.         IF m > 2 THEN d = d + 1 'add an extra day for leap year every 4 years, starting in 1970
  21.     NEXT
  22.     d = d - 1 'for year 2000
  23.     s~&& = d * 24 * 60 * 60 'Seconds are days * 24 hours * 60 minutes * 60 seconds
  24.     ExtendedTimer## = (s~&& + TIMER)

Most of us write time code to test little snippets for which method might be faster for us while we're coding.  The clock resetting on us isn't normally such a big deal.  When it is, however, all you have to do is swap to the ExtendedTimer function above -- it returns a value for you based off DAY + TIME, rather than just time alone!  No midnight clock issues with something like that in our programs.  ;)

    ' DO SOMETHING FOR 3 SECONDS
    t# = ExtendedTimer + 3
    Do
        '(SOMETHING)
    Loop Until Timer > t#
Title: Re: how to time something (ie do loop for n seconds)
Post by: madscijr on February 23, 2022, 12:02:34 pm
Quote from: SMcNeill on February 23, 2022, 11:26:52 am
One caveat here:  You *can* experience bugs with this after midnight.
...
I'd suggest just plugging in my ExtendedTimer and use it instead:
...

That could definitely throw a wrench in the works, especially for us night owls or for any programs running around midnight. I'll add your routine to the toolbox. And thanks!
Title: Re: how to time something (ie do loop for n seconds)
Post by: mdijkens on February 28, 2022, 05:35:39 pm
Quote from: SMcNeill on February 23, 2022, 11:26:52 am
One caveat here:  You *can* experience bugs with this after midnight.

Program starts at 23:59:59.  Add three seconds -- 24:00:02...  (In seconds, and not hours and minutes like this, though hours and minutes are easier to visualize.)

Clock hits midnight:  0:00:00

At no point will you ever have TIMER become greater than t#.

If it is not that critical for normal situations I always used:

Code: QB64: [Select]
  1. Tim! = Timer
  2. Do While Abs(Timer - Tim!) < 10
  3.   ' Try something over and over again for 10 seconds
  5.  

and yes, around midnight you might have one shorter loop, but in most cases that's not so critical
Title: Re: how to time something (ie do loop for n seconds)
Post by: bplus on February 28, 2022, 05:55:18 pm
add a check for passing midnight
If Timer - Tim! < 0 then add days worth of seconds = 24 * 60 *60 else daysworth = 0

then do the
If timer + daysworth - Tim! ....
Title: Re: how to time something (ie do loop for n seconds)
Post by: mdijkens on February 28, 2022, 06:15:25 pm
If it is important without an extra condition
Code: QB64: [Select]
  1. Tim! = Timer
  2. Do While (86400 + Timer - Tim!) Mod 86400 < 10
  3.   ' Try something over and over again for 10 seconds
  5.  
Title: Re: how to time something (ie do loop for n seconds)
Post by: bplus on February 28, 2022, 06:27:44 pm
Nice that might work!
Title: Re: how to time something (ie do loop for n seconds)
Post by: CharlieJV on February 28, 2022, 08:02:06 pm
Quote from: SMcNeill on February 23, 2022, 11:26:52 am
One caveat here:  You *can* experience bugs with this after midnight.

(SNIP!)

Well, reflexes of a sloth here, yet this was instantaneous:
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