Date: Fri, 1 Jun 2001 16:18:08 -0700 (PDT) From: David Wolfskill <david@catwhisker.org> To: stable@freebsd.org Subject: Re: time_t definition is worng Message-ID: <200106012318.f51NI8w38590@bunrab.catwhisker.org> In-Reply-To: <200106012300.f51N0VT90830@earth.backplane.com>
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>Date: Fri, 1 Jun 2001 16:00:31 -0700 (PDT)
>From: Matt Dillon <dillon@earth.backplane.com>
>:I never understood why it isn't at _least_ made unsigned. This at least
>:puts off the 2038 issue until 2106. I may live to see the former, but
>:certainly not the latter. :-)
> Historically people compared time stamps by subtracting one from
> another.
Which is a practice that the difftime() function was invented to
replace.
> If they are unsigned, that breaks horribly (you never get
> a negative result).
Ummm. With respect, I think the excerpt from "man 3 time" that reads:
Upon successful completion, time() returns the value of time. Otherwise
a value of ((time_t) -1) is returned and the global variable errno is set
to indicate the error.
is probably a more significant restriction: both could be gotten around
if time_t were unsigned, but in the mean time (no pun intended!), I suspect
that a lot of naively-coded applications would break mysteriously.
> Internally there is nothing preventing us from
> treating time_t as an unsigned, er, long.
Well, I don't write much code (and never have written a lot of it), so
please feel free to take what I wrote with an appropriately-sized
"grain of salt". But it may be worth noting (iin this context) that
the result of difftime() is a double. :-}
Cheers,
david
--
David H. Wolfskill david@catwhisker.org
As a computing professional, I believe it would be unethical for me to
advise, recommend, or support the use (save possibly for personal
amusement) of any product that is or depends on any Microsoft product.
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