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Groups > comp.lang.c > #102082
| Newsgroups | comp.lang.c |
|---|---|
| Date | 2017-01-17 13:45 -0800 |
| References | <863e4550-027a-4d32-b5df-e34f2c7b4439@googlegroups.com> <o5g9bs$a87$1@dont-email.me> <cb9326d0-4c2d-42ff-8f41-d779129c671b@googlegroups.com> <o5m13v$kjf$1@dont-email.me> |
| Message-ID | <2f7f0a41-541e-447e-8beb-e9da847e7526@googlegroups.com> (permalink) |
| Subject | Re: Dinamic array without malloc - Can be done? |
| From | fir <profesor.fir@gmail.com> |
W dniu wtorek, 17 stycznia 2017 22:10:05 UTC+1 użytkownik Bart napisał:
> On 15/01/2017 17:34, fir wrote:
> > W dniu niedziela, 15 stycznia 2017 17:53:57 UTC+1 użytkownik Bart napisał:
> >> On 15/01/2017 16:45, Fernando D. Bozzo wrote:
> >>> From the beginning of my course I'm looking a way to define an array with a number of elements based on some other variable which I don't know, but without using the dynamic memory space (with malloc)
> >>>
> >>> May be I have a conceptual error here, but just in case I did prefer to ask.
> >>>
> >>> I want to do something like this:
> >>>
> >>> len = (some calculated length that can vary in every execution);
> >>> char myArray[len];
> >>>
> >>>
> >>> I've tryied this way, but didn't compile. My aim is not needing to free() it later, but that this array get cleared as all other auto variables.
> >>
> >> It should work; did you put the code inside a function? Eg:
> >>
> >> int main(void) {
> >> int len=rand()+100;
> >> char myArray[len];
> >>
> >> printf("%d\n",(int)sizeof(myArray));
> >>
> >> }
> >>
> >> The array is allocated on the stack and is deallocated at a matching "}".
> >>
> >> (This is a C 'VLA'.)
> >>
> >
> > i should rethink the limits of this method.. do you know them maybe? (many arrays could be used in function body?
> > each one freely resized? etc)
>
> Any number of such arrays can be declared.
>
> The space is deallocated at the end of the block in which the array is
> declared. Or by leaving the block via goto or return.
>
> They can't be resized except by 're-executing' the declaration:
>
> int n;
>
> n=10;
> {
> L:;
> char a[n];
>
> printf("SIZE=%d\n",sizeof(a));
> n=n*2;
> if (n<100) goto L;
> }
>
> This prints 10, 20, 40 and 80.
>
> I've no idea how it manages it, since it is presumably deallocating and
> then reallocating even within the same block. The compiler does however
> stop you jumping /into/ such a block (by-passing the declaration for
> example).
>
> So in all it's a nasty little feature IMO full of gotchas if you're
> unfortunate enough to have the job of implementing it.
>
> (And which I would never use, except by accident, as my need is for
> flexible arrays that which grow in size.)
>
this not leaves the block so i thought it shouldnt
resize... but i dont know.. some said on this that 1] it
not accumulates allocations (unlike alloca).. 2] thought it is also not resizable (like alloca made).. 3] and it deallocks after block exit (unlike alloca)
i dont think it should be hard to implement.. what could be hard? you will only need to remember stack pointer
locations and revert to it after leaving the block, something like that..
more problem is if this has sense.. it may have some
sense.. though for example as local variables in blocks
are not 'deleted' after block exit (afair) but are unaccesible (afair) maybe here it should work this way
(im not sure).... btw if it is ok with those variables im also not sure (in both cases if they should be deleted
and if should be necessarely unaccesible )
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Dinamic array without malloc - Can be done? "Fernando D. Bozzo" <fdbozzo@gmail.com> - 2017-01-15 08:45 -0800
Re: Dinamic array without malloc - Can be done? BartC <bc@freeuk.com> - 2017-01-15 16:53 +0000
Re: Dinamic array without malloc - Can be done? fir <profesor.fir@gmail.com> - 2017-01-15 09:34 -0800
Re: Dinamic array without malloc - Can be done? BartC <bc@freeuk.com> - 2017-01-17 21:09 +0000
Re: Dinamic array without malloc - Can be done? fir <profesor.fir@gmail.com> - 2017-01-17 13:45 -0800
Re: Dinamic array without malloc - Can be done? fir <profesor.fir@gmail.com> - 2017-01-17 14:09 -0800
Re: Dinamic array without malloc - Can be done? BartC <bc@freeuk.com> - 2017-01-17 22:41 +0000
Re: Dinamic array without malloc - Can be done? supercat@casperkitty.com - 2017-01-17 15:06 -0800
Re: Dinamic array without malloc - Can be done? fir <profesor.fir@gmail.com> - 2017-01-17 16:49 -0800
Re: Dinamic array without malloc - Can be done? Keith Thompson <kst-u@mib.org> - 2017-01-17 16:56 -0800
Re: Dinamic array without malloc - Can be done? supercat@casperkitty.com - 2017-01-17 20:37 -0800
Re: Dinamic array without malloc - Can be done? David Brown <david.brown@hesbynett.no> - 2017-01-18 09:38 +0100
Re: Dinamic array without malloc - Can be done? Tim Rentsch <txr@alumni.caltech.edu> - 2017-01-31 08:49 -0800
Re: Dinamic array without malloc - Can be done? supercat@casperkitty.com - 2017-01-31 10:39 -0800
Re: Dinamic array without malloc - Can be done? luser droog <luser.droog@gmail.com> - 2017-01-31 10:55 -0800
Re: Dinamic array without malloc - Can be done? supercat@casperkitty.com - 2017-01-31 11:40 -0800
Re: Dinamic array without malloc - Can be done? "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2017-01-31 10:57 -0800
Re: Dinamic array without malloc - Can be done? Tim Rentsch <txr@alumni.caltech.edu> - 2017-02-03 23:06 -0800
Re: Dinamic array without malloc - Can be done? "Fernando D. Bozzo" <fdbozzo@gmail.com> - 2017-01-15 10:42 -0800
Re: Dinamic array without malloc - Can be done? BartC <bc@freeuk.com> - 2017-01-15 20:15 +0000
Re: Dinamic array without malloc - Can be done? Keith Thompson <kst-u@mib.org> - 2017-01-15 12:43 -0800
Re: Dinamic array without malloc - Can be done? "Fernando D. Bozzo" <fdbozzo@gmail.com> - 2017-01-15 15:08 -0800
Re: Dinamic array without malloc - Can be done? "James R. Kuyper" <jameskuyper@verizon.net> - 2017-01-15 12:25 -0500
Re: Dinamic array without malloc - Can be done? "Fernando D. Bozzo" <fdbozzo@gmail.com> - 2017-01-15 10:46 -0800
Re: Dinamic array without malloc - Can be done? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-01-15 20:13 +0000
Re: Dinamic array without malloc - Can be done? "Fernando D. Bozzo" <fdbozzo@gmail.com> - 2017-01-15 15:06 -0800
Re: Dinamic array without malloc - Can be done? Keith Thompson <kst-u@mib.org> - 2017-01-15 12:46 -0800
Re: Dinamic array without malloc - Can be done? "James R. Kuyper" <jameskuyper@verizon.net> - 2017-01-15 16:10 -0500
Re: Dinamic array without malloc - Can be done? Tim Rentsch <txr@alumni.caltech.edu> - 2017-01-15 20:37 -0800
Re: Dinamic array without malloc - Can be done? Keith Thompson <kst-u@mib.org> - 2017-01-15 21:02 -0800
Re: Dinamic array without malloc - Can be done? Tim Rentsch <txr@alumni.caltech.edu> - 2017-01-30 04:23 -0800
Re: Dinamic array without malloc - Can be done? David Brown <david.brown@hesbynett.no> - 2017-01-16 09:05 +0100
Re: Dinamic array without malloc - Can be done? Ian Collins <ian-news@hotmail.com> - 2017-01-16 21:16 +1300
Re: Dinamic array without malloc - Can be done? David Brown <david.brown@hesbynett.no> - 2017-01-16 09:48 +0100
Re: Dinamic array without malloc - Can be done? fir <profesor.fir@gmail.com> - 2017-01-15 09:29 -0800
Re: Dinamic array without malloc - Can be done? fir <profesor.fir@gmail.com> - 2017-01-15 09:37 -0800
Re: Dinamic array without malloc - Can be done? fir <profesor.fir@gmail.com> - 2017-01-15 09:56 -0800
Re: Dinamic array without malloc - Can be done? fir <profesor.fir@gmail.com> - 2017-01-15 10:34 -0800
Re: Dinamic array without malloc - Can be done? "Fernando D. Bozzo" <fdbozzo@gmail.com> - 2017-01-15 10:48 -0800
Re: Dinamic array without malloc - Can be done? fir <profesor.fir@gmail.com> - 2017-01-15 11:10 -0800
Re: Dinamic array without malloc - Can be done? Jean-Marc Bourguet <jm@bourguet.org> - 2017-01-15 20:22 +0100
Re: Dinamic array without malloc - Can be done? Chad <cdalten@gmail.com> - 2017-01-15 11:50 -0800
Re: Dinamic array without malloc - Can be done? "Fernando D. Bozzo" <fdbozzo@gmail.com> - 2017-01-15 15:12 -0800
Re: Dinamic array without malloc - Can be done? Richard Heathfield <rjh@cpax.org.uk> - 2017-01-15 17:50 +0000
Re: Dinamic array without malloc - Can be done? "Fernando D. Bozzo" <fdbozzo@gmail.com> - 2017-01-15 10:38 -0800
Re: Dinamic array without malloc - Can be done? Richard Heathfield <rjh@cpax.org.uk> - 2017-01-15 19:34 +0000
Re: Dinamic array without malloc - Can be done? Keith Thompson <kst-u@mib.org> - 2017-01-15 12:51 -0800
Re: Dinamic array without malloc - Can be done? supercat@casperkitty.com - 2017-01-15 13:10 -0800
Re: Dinamic array without malloc - Can be done? Keith Thompson <kst-u@mib.org> - 2017-01-15 16:23 -0800
Re: Dinamic array without malloc - Can be done? supercat@casperkitty.com - 2017-01-15 18:08 -0800
Re: Dinamic array without malloc - Can be done? David Brown <david.brown@hesbynett.no> - 2017-01-16 09:56 +0100
Re: Dinamic array without malloc - Can be done? supercat@casperkitty.com - 2017-01-16 08:35 -0800
Re: Dinamic array without malloc - Can be done? "Chris M. Thomasson" <invalid@invalid.invalid> - 2017-01-16 11:07 -0800
Re: Dinamic array without malloc - Can be done? "Chris M. Thomasson" <invalid@invalid.invalid> - 2017-01-16 11:17 -0800
Re: Dinamic array without malloc - Can be done? Robert Wessel <robertwessel2@yahoo.com> - 2017-01-16 15:21 -0600
Re: Dinamic array without malloc - Can be done? "Chris M. Thomasson" <invalid@invalid.invalid> - 2017-01-31 22:22 -0800
Re: Dinamic array without malloc - Can be done? David Brown <david.brown@hesbynett.no> - 2017-01-17 00:22 +0100
Re: Dinamic array without malloc - Can be done? supercat@casperkitty.com - 2017-01-16 16:23 -0800
Re: Dinamic array without malloc - Can be done? David Brown <david.brown@hesbynett.no> - 2017-01-17 02:04 +0100
Re: Dinamic array without malloc - Can be done? supercat@casperkitty.com - 2017-01-16 17:27 -0800
Re: Dinamic array without malloc - Can be done? David Brown <david.brown@hesbynett.no> - 2017-01-17 09:16 +0100
Re: Dinamic array without malloc - Can be done? Tim Rentsch <txr@alumni.caltech.edu> - 2017-01-15 20:32 -0800
Re: Dinamic array without malloc - Can be done? David Brown <david.brown@hesbynett.no> - 2017-01-16 10:02 +0100
Re: Dinamic array without malloc - Can be done? Keith Thompson <kst-u@mib.org> - 2017-01-16 09:22 -0800
Re: Dinamic array without malloc - Can be done? David Brown <david.brown@hesbynett.no> - 2017-01-17 00:25 +0100
Re: Dinamic array without malloc - Can be done? Barry Schwarz <schwarzb@dqel.com> - 2017-01-15 11:53 -0800
Re: Dinamic array without malloc - Can be done? fir <profesor.fir@gmail.com> - 2017-01-15 12:22 -0800
Re: Dinamic array without malloc - Can be done? "Fernando D. Bozzo" <fdbozzo@gmail.com> - 2017-01-15 15:32 -0800
Re: Dinamic array without malloc - Can be done? supercat@casperkitty.com - 2017-01-15 16:01 -0800
Re: Dinamic array without malloc - Can be done? David Brown <david.brown@hesbynett.no> - 2017-01-16 10:19 +0100
Re: Dinamic array without malloc - Can be done? BartC <bc@freeuk.com> - 2017-01-16 11:28 +0000
Re: Dinamic array without malloc - Can be done? David Brown <david.brown@hesbynett.no> - 2017-01-16 14:29 +0100
Re: Dinamic array without malloc - Can be done? BartC <bc@freeuk.com> - 2017-01-16 15:41 +0000
Re: Dinamic array without malloc - Can be done? David Brown <david.brown@hesbynett.no> - 2017-01-16 17:27 +0100
Re: Dinamic array without malloc - Can be done? supercat@casperkitty.com - 2017-01-16 07:56 -0800
Re: Dinamic array without malloc - Can be done? David Brown <david.brown@hesbynett.no> - 2017-01-16 17:31 +0100
Re: Dinamic array without malloc - Can be done? supercat@casperkitty.com - 2017-01-16 08:48 -0800
Re: Dinamic array without malloc - Can be done? David Brown <david.brown@hesbynett.no> - 2017-01-17 00:29 +0100
Re: Dinamic array without malloc - Can be done? "Chris M. Thomasson" <invalid@invalid.invalid> - 2017-01-16 11:25 -0800
Re: Dinamic array without malloc - Can be done? supercat@casperkitty.com - 2017-01-16 12:28 -0800
Re: Dinamic array without malloc - Can be done? "Chris M. Thomasson" <invalid@invalid.invalid> - 2017-01-16 12:38 -0800
Re: Dinamic array without malloc - Can be done? Keith Thompson <kst-u@mib.org> - 2017-01-15 16:57 -0800
Re: Dinamic array without malloc - Can be done? "Fernando D. Bozzo" <fdbozzo@gmail.com> - 2017-01-16 00:37 -0800
Re: Dinamic array without malloc - Can be done? David Brown <david.brown@hesbynett.no> - 2017-01-16 10:23 +0100
Re: Dinamic array without malloc - Can be done? "Fernando D. Bozzo" <fdbozzo@gmail.com> - 2017-01-16 01:35 -0800
Re: Dinamic array without malloc - Can be done? Keith Thompson <kst-u@mib.org> - 2017-01-16 09:15 -0800
Re: Dinamic array without malloc - Can be done? BartC <bc@freeuk.com> - 2017-01-16 01:29 +0000
Re: Dinamic array without malloc - Can be done? David Brown <david.brown@hesbynett.no> - 2017-01-16 10:08 +0100
Re: Dinamic array without malloc - Can be done? supercat@casperkitty.com - 2017-01-16 08:08 -0800
Re: Dinamic array without malloc - Can be done? David Brown <david.brown@hesbynett.no> - 2017-01-17 00:35 +0100
Re: Dinamic array without malloc - Can be done? supercat@casperkitty.com - 2017-01-16 16:31 -0800
Re: Dinamic array without malloc - Can be done? David Brown <david.brown@hesbynett.no> - 2017-01-17 09:27 +0100
Re: Dinamic array without malloc - Can be done? BartC <bc@freeuk.com> - 2017-01-17 12:11 +0000
Re: Dinamic array without malloc - Can be done? David Brown <david.brown@hesbynett.no> - 2017-01-17 14:23 +0100
Re: Dinamic array without malloc - Can be done? supercat@casperkitty.com - 2017-01-17 05:38 -0800
Re: Dinamic array without malloc - Can be done? BartC <bc@freeuk.com> - 2017-01-17 14:17 +0000
Re: Dinamic array without malloc - Can be done? supercat@casperkitty.com - 2017-01-17 07:09 -0800
Re: Dinamic array without malloc - Can be done? supercat@casperkitty.com - 2017-01-17 05:14 -0800
Re: Dinamic array without malloc - Can be done? David Brown <david.brown@hesbynett.no> - 2017-01-17 14:40 +0100
Re: Dinamic array without malloc - Can be done? supercat@casperkitty.com - 2017-01-17 06:41 -0800
Re: Dinamic array without malloc - Can be done? David Brown <david.brown@hesbynett.no> - 2017-01-17 16:00 +0100
Re: Dinamic array without malloc - Can be done? supercat@casperkitty.com - 2017-01-17 07:45 -0800
Re: Dinamic array without malloc - Can be done? fir <profesor.fir@gmail.com> - 2017-01-17 08:18 -0800
Re: Dinamic array without malloc - Can be done? fir <profesor.fir@gmail.com> - 2017-01-17 08:27 -0800
Re: Dinamic array without malloc - Can be done? supercat@casperkitty.com - 2017-01-17 09:29 -0800
Re: Dinamic array without malloc - Can be done? supercat@casperkitty.com - 2017-01-17 09:23 -0800
Re: Dinamic array without malloc - Can be done? fir <profesor.fir@gmail.com> - 2017-01-17 10:35 -0800
Re: Dinamic array without malloc - Can be done? supercat@casperkitty.com - 2017-01-17 12:41 -0800
Re: Dinamic array without malloc - Can be done? fir <profesor.fir@gmail.com> - 2017-01-17 13:45 -0800
Re: Dinamic array without malloc - Can be done? Robert Wessel <robertwessel2@yahoo.com> - 2017-01-17 21:00 -0600
Re: Dinamic array without malloc - Can be done? fir <profesor.fir@gmail.com> - 2017-01-15 11:55 -0800
Re: Dinamic array without malloc - Can be done? Siri Cruise <chine.bleu@yahoo.com> - 2017-01-15 14:59 -0800
Re: Dinamic array without malloc - Can be done? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-01-15 20:04 +0000
Re: Dinamic array without malloc - Can be done? David Brown <david.brown@hesbynett.no> - 2017-01-15 21:33 +0100
Re: Dinamic array without malloc - Can be done? supercat@casperkitty.com - 2017-01-15 13:00 -0800
Re: Dinamic array without malloc - Can be done? Tim Rentsch <txr@alumni.caltech.edu> - 2017-01-15 20:27 -0800
Re: Dinamic array without malloc - Can be done? "James R. Kuyper" <jameskuyper@verizon.net> - 2017-01-15 16:34 -0500
Re: Dinamic array without malloc - Can be done? "James R. Kuyper" <jameskuyper@verizon.net> - 2017-01-15 16:43 -0500
Re: Dinamic array without malloc - Can be done? Keith Thompson <kst-u@mib.org> - 2017-01-15 16:17 -0800
Re: Dinamic array without malloc - Can be done? Tim Rentsch <txr@alumni.caltech.edu> - 2017-01-15 20:22 -0800
Re: Dinamic array without malloc - Can be done? Keith Thompson <kst-u@mib.org> - 2017-01-15 21:00 -0800
Re: Dinamic array without malloc - Can be done? Tim Rentsch <txr@alumni.caltech.edu> - 2017-01-30 05:01 -0800
Re: Dinamic array without malloc - Can be done? Keith Thompson <kst-u@mib.org> - 2017-01-30 11:35 -0800
Re: Dinamic array without malloc - Can be done? Tim Rentsch <txr@alumni.caltech.edu> - 2017-02-01 16:18 -0800
Re: Dinamic array without malloc - Can be done? supercat@casperkitty.com - 2017-02-01 16:37 -0800
Re: Dinamic array without malloc - Can be done? Robert Wessel <robertwessel2@yahoo.com> - 2017-02-01 23:21 -0600
Re: Dinamic array without malloc - Can be done? Tim Rentsch <txr@alumni.caltech.edu> - 2017-02-02 00:27 -0800
Re: Dinamic array without malloc - Can be done? supercat@casperkitty.com - 2017-02-02 10:58 -0800
Re: Dinamic array without malloc - Can be done? Tim Rentsch <txr@alumni.caltech.edu> - 2017-02-03 22:51 -0800
Re: Dinamic array without malloc - Can be done? "Chris M. Thomasson" <invalid@invalid.invalid> - 2017-01-15 15:41 -0800
Re: Dinamic array without malloc - Can be done? "Fernando D. Bozzo" <fdbozzo@gmail.com> - 2017-01-15 15:44 -0800
Re: Dinamic array without malloc - Can be done? "Chris M. Thomasson" <invalid@invalid.invalid> - 2017-01-15 16:17 -0800
Re: Dinamic array without malloc - Can be done? Alla _ <modelling.data@gmail.com> - 2017-01-16 01:47 -0800
Re: Dinamic array without malloc - Can be done? "Fernando D. Bozzo" <fdbozzo@gmail.com> - 2017-01-16 01:50 -0800
Re: Dinamic array without malloc - Can be done? Alla _ <modelling.data@gmail.com> - 2017-01-16 02:38 -0800
Re: Dinamic array without malloc - Can be done? "Fernando D. Bozzo" <fdbozzo@gmail.com> - 2017-01-16 03:15 -0800
Re: Dinamic array without malloc - Can be done? Alla _ <modelling.data@gmail.com> - 2017-01-16 03:40 -0800
Re: Dinamic array without malloc - Can be done? "Fernando D. Bozzo" <fdbozzo@gmail.com> - 2017-01-16 04:21 -0800
Re: Dinamic array without malloc - Can be done? Alla _ <modelling.data@gmail.com> - 2017-01-16 04:29 -0800
Re: Dinamic array without malloc - Can be done? "Fernando D. Bozzo" <fdbozzo@gmail.com> - 2017-01-16 04:36 -0800
Re: Dinamic array without malloc - Can be done? Richard Heathfield <rjh@cpax.org.uk> - 2017-01-16 11:36 +0000
Re: Dinamic array without malloc - Can be done? Alla _ <modelling.data@gmail.com> - 2017-01-16 03:44 -0800
Re: Dinamic array without malloc - Can be done? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-01-16 15:34 +0000
Re: Dinamic array without malloc - Can be done? Richard Heathfield <rjh@cpax.org.uk> - 2017-01-16 16:01 +0000
Re: Dinamic array without malloc - Can be done? John Bode <jfbode1029@gmail.com> - 2017-01-17 10:14 -0800
Re: Dinamic array without malloc - Can be done? James Kuyper <jameskuyper@verizon.net> - 2017-01-17 13:21 -0500
Re: Dinamic array without malloc - Can be done? John Bode <jfbode1029@gmail.com> - 2017-01-17 11:43 -0800
Re: Dinamic array without malloc - Can be done? James Kuyper <jameskuyper@verizon.net> - 2017-01-17 15:07 -0500
Re: Dinamic array without malloc - Can be done? supercat@casperkitty.com - 2017-01-17 12:24 -0800
Re: Dinamic array without malloc - Can be done? "Fernando D. Bozzo" <fdbozzo@gmail.com> - 2017-01-17 10:24 -0800
Re: Dinamic array without malloc - Can be done? Tim Rentsch <txr@alumni.caltech.edu> - 2017-01-30 05:21 -0800
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