Date: Tue, 8 Aug 2000 20:44:55 +0100 From: Mark Ovens <marko@freebsd.org> To: Alfred Perlstein <bright@wintelcom.net> Cc: chat@FreeBSD.ORG Subject: Re: C time functions - problem Message-ID: <20000808204455.J250@parish> In-Reply-To: <20000808122832.I4854@fw.wintelcom.net>; from bright@wintelcom.net on Tue, Aug 08, 2000 at 12:28:32PM -0700 References: <20000808201807.H250@parish> <20000808122832.I4854@fw.wintelcom.net>
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On Tue, Aug 08, 2000 at 12:28:32PM -0700, Alfred Perlstein wrote:
> * Mark Ovens <marko@FreeBSD.ORG> [000808 12:21] wrote:
> > Can anyone tell me why the call to localtime() in the code below
> > should segfault in tzset()?
> >
> > Running it in the debugger shows that ``t'' is set to a sensible
> > value.
> >
> > Program received signal SIGSEGV, Segmentation fault.
> > 0x280be4c8 in tzset () from /usr/lib/libc.so.4
> >
> >
> > #include <stdio.h>
> > #include <time.h>
> >
> > int main() {
> > struct tm *timeptr;
> > char buf[BUFSIZ];
> > size_t size;
> > time_t t;
> >
> > tzset;
> >
> > t = time((time_t *)0);
> > timeptr = localtime((time_t *)t);
> >
> > .....
>
> Please don't do disgusting things with casts.
>
> Do not cast a time_t to a time_t *, they aren't the same.
>
Arghh! The perils of copy 'n' pasting. I spend ages staring at
it trying to see the error then as soon as someone points it out it
leaps out at me ("wood" and "trees" spring to mind).
Thanks.
> Don't cast 0 to a pointer type, use NULL.
>
> Remove the overzealous casting and your programming error should
> become clear.
>
> --
> -Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org]
> "I have the heart of a child; I keep it in a jar on my desk."
--
4.4 - The number of the Beastie
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