how to time something (ie do loop for n seconds)

[madscijr]

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

[SMcNeill]

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)
25. END FUNCTION

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#

[madscijr]

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!

[mdijkens]

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
4. Loop
5.  

and yes, around midnight you might have one shorter loop, but in most cases that's not so critical

[bplus]

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! ....

[mdijkens]

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
4. Loop
5.  

[bplus]

Nice that might work!

[CharlieJV]

One caveat here:  You *can* experience bugs with this after midnight.

(SNIP!)

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