Date: Sat, 13 Jul 2002 17:47:55 +0200 From: Ingo Oeser <ingo.oeser@informatik.tu-chemnitz.de> To: "Brian T.Schellenberger" <bts@babbleon.org> Cc: Yar Tikhiy <yar@comp.chem.msu.su>, hackers@FreeBSD.ORG Subject: Re: Large variables on stack Message-ID: <20020713174755.E758@nightmaster.csn.tu-chemnitz.de> In-Reply-To: <20020712155951.B4F0BBA05@i8k.babbleon.org>; from bts@babbleon.org on Fri, Jul 12, 2002 at 11:59:51AM -0400 References: <20020712194809.A62768@comp.chem.msu.su> <20020712155951.B4F0BBA05@i8k.babbleon.org>
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Hi,
On Fri, Jul 12, 2002 at 11:59:51AM -0400, Brian T.Schellenberger wrote:
> Besides, stack allocations are more efficient than heap allocations on every
> architecture I know of other than the IBM mainframe.
>
> Of course, it's is a lot better to dynamically allocate strings of unknown
> length than to use large stack buffers, but that's because the dynamic
> allocation can be done after you know the length of the string and can avoid
> overflows more than because you don't want large stack allocations.
You can always do strlen() before and pass that on to your
subfunctions. I also like the approach of storing strings
together with its length, but is is very un-C.
> In a language like ForTran that allows variable-length
> automatically-allocated function-scoped items I'd do even those
> off of the stack.
C99 is also such a language and at least GCC supports it just
fine even in scopes.
The following (useless) programs demonstrates this:
#include <stdlib.h>
#include <stdio.h>
void print_arg(char *s) {
size_t len=strlen(s)+1;
{
char d[len];
memcpy(&d[0],s,len);
printf("%s\n",&d[0]);
}
}
int main(int argc, char **argv) {
int i;
for (i=0; i<argc; i++) if (argv[i]) print_arg(argv[i]);
return 0;
}
Regards
Ingo Oeser
--
Science is what we can tell a computer. Art is everything else. --- D.E.Knuth
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