Re: "A diagram of C23 basic types"

BGB <cr88192@gmail.com> writes:

On 4/16/2025 3:04 PM, Scott Lurndal wrote:

Keith Thompson <Keith.S.Thompson+u@gmail.com> writes:

candycanearter07 <candycanearter07@candycanearter07.nomail.afraid>
writes:

[...]

Datetime is a nightmare, this is why we use a simple seconds-since-X
system.

>
Indeed.  That makes it a slightly less unpleasant nightmare.

Back in the mainframe days, it was common to use julian dates
as they were both concise (5 BCD digits/20 bits) and sortable.
   YYDDD
If time was neeeded, it was seconds since midnight in a reference
timezone.

>
One shorthand is to assume a year is 365.25 days (31557600 seconds),
and then base everything else off this (initially ignoring things like
leap-years, etc, just assume that the number of days per year is
fractional).
>
Then, say, 2629800 seconds per month, ...

So, a month is 30 days, 26 hours, and 15 minutes.  How is that useful?

For some other calculations, one can assume an integer number of days
(365), just that each day is 0.07% longer.
>
For date/time calculations, one could then "guess" the date, and
jitter it back/forth as needed until it was consistent with the
calendar math.
>
Estimate and subtract the year, estimate and subtract the month, then
the day. Then if we have landed on the wrong day, adjust until it
fits.
>
Not really sure if there was a more standard way to do this.

Keeping track of time in a manner that's entirely consistent with
the Gregorian calendar is a solved problem.  C's standard library
has functions that will do that for you.  What is the point of
inventing a new and less accurate approximation?

[...]

As for time since epoch:
Microseconds (in a power-of-10 sense) are more common...

The C standard library already has "struct timespec", which represents
time with nanosecond precision.  Why invent something new with poorer
precision?

[...]

--
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
void Void(void) { Void(); } /* The recursive call of the void */