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Groups > comp.lang.c > #58762

Re: local arrays and stack

From Bartc <bc@freeuk.com>
Newsgroups comp.lang.c
Subject Re: local arrays and stack
Date 2015-03-23 16:34 +0000
Organization A noiseless patient Spider
Message-ID <mepfa1$26r$1@dont-email.me> (permalink)
References (3 earlier) <i0nvgahdv9uuetqfqg60eee3ln1jct1720@4ax.com> <87k2y7u48c.fsf@kst-u.example.com> <705a5674-dbc9-460a-a72c-50bf1946be01@googlegroups.com> <mepdmh$qso$1@dont-email.me> <87fv8vu1sx.fsf@kst-u.example.com>

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On 23/03/2015 16:16, Keith Thompson wrote:
> Bartc <bc@freeuk.com> writes:
>> On 23/03/2015 15:42, fir wrote:
>>> W dniu poniedziałek, 23 marca 2015 16:24:12 UTC+1 użytkownik Keith Thompson napisał:
>>>> MinGW uses gcc as its compiler.  As far as I know, all local non-static
>>>> objects (i.e., objects with automatic storage duration), including
>>>> arrays of any size, are allocated on the stack.
>>>>
>>> any size?
>>>
>>>    i thought that large ones are 'silently' moved to static area
>>> (stack is small, probably 2MB limit usually so how it could contain
>>> larger arrays? it could be silent move out of stack or compile
>>> error) (i may be mistaken here))
>>
>> The stack can grow. Large local arrays can also be allocated on the
>> heap. It's up to the compiler.
>
> Does gcc *ever* (generate code to) allocate local non-static arrays
> on the heap or in static memory?  It would have to generate code to
> explicitly deallocate the array, even in the presence of a goto or
> longjmp() out of the scope.  Certainly a compiler *could* do that,
> but I've never heard of gcc in particular doing so.

I don't know what gcc in particular does. But if allocating a VLA, 
perhaps inside a block which is the body of a loop, and the size is 
different each time, then wouldn't it have to take of such details 
anyway? Including dealing with goto, break, longjmp and return.

Then using the heap wouldn't be much different.

(And I've done this, but not in a C-like language and within function 
scopes only, not inner block scopes . In C++ of course, anything is 
possible.)

-- 
Bartc

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Thread

local arrays and stack fir <profesor.fir@gmail.com> - 2015-03-22 01:51 -0700
  local arrays and stack asetofsymbols@gmail.com - 2015-03-22 02:23 -0700
  Re: local arrays and stack Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-03-22 13:22 -0700
    Re: local arrays and stack fir <profesor.fir@gmail.com> - 2015-03-23 01:55 -0700
  Re: local arrays and stack Xcott Craver <xcottcraver@gmail.com> - 2015-03-22 15:07 -0700
    Re: local arrays and stack fir <profesor.fir@gmail.com> - 2015-03-23 01:50 -0700
      Re: local arrays and stack Robert Wessel <robertwessel2@yahoo.com> - 2015-03-23 04:26 -0500
        Re: local arrays and stack fir <profesor.fir@gmail.com> - 2015-03-23 06:53 -0700
        Re: local arrays and stack Xcott Craver <xcottcraver@gmail.com> - 2015-03-23 07:29 -0700
          Re: local arrays and stack fir <profesor.fir@gmail.com> - 2015-03-23 08:34 -0700
          Re: local arrays and stack Robert Wessel <robertwessel2@yahoo.com> - 2015-03-23 19:57 -0500
          Re: local arrays and stack fir <profesor.fir@gmail.com> - 2015-03-24 04:01 -0700
            Re: local arrays and stack fir <profesor.fir@gmail.com> - 2015-03-24 04:37 -0700
            Re: local arrays and stack David Brown <david.brown@hesbynett.no> - 2015-03-24 13:04 +0100
              Re: local arrays and stack glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-03-24 17:29 +0000
                Re: local arrays and stack David Brown <david.brown@hesbynett.no> - 2015-03-24 20:01 +0100
        Re: local arrays and stack Keith Thompson <kst-u@mib.org> - 2015-03-23 08:24 -0700
          Re: local arrays and stack fir <profesor.fir@gmail.com> - 2015-03-23 08:42 -0700
            Re: local arrays and stack Bartc <bc@freeuk.com> - 2015-03-23 16:07 +0000
              Re: local arrays and stack fir <profesor.fir@gmail.com> - 2015-03-23 09:15 -0700
              Re: local arrays and stack Keith Thompson <kst-u@mib.org> - 2015-03-23 09:16 -0700
                Re: local arrays and stack Bartc <bc@freeuk.com> - 2015-03-23 16:34 +0000
                Re: local arrays and stack Xcott Craver <xcottcraver@gmail.com> - 2015-03-23 10:12 -0700
                Re: local arrays and stack Bartc <bc@freeuk.com> - 2015-03-23 17:44 +0000
                Re: local arrays and stack fir <profesor.fir@gmail.com> - 2015-03-23 11:47 -0700
                Re: local arrays and stack Xcott Craver <xcottcraver@gmail.com> - 2015-03-23 12:06 -0700
                Re: local arrays and stack Bartc <bc@freeuk.com> - 2015-03-23 20:25 +0000
                Re: local arrays and stack Xcott Craver <xcottcraver@gmail.com> - 2015-03-23 14:10 -0700
                Re: local arrays and stack Bartc <bc@freeuk.com> - 2015-03-23 22:22 +0000
                Re: local arrays and stack fir <profesor.fir@gmail.com> - 2015-03-23 23:57 -0700
                Re: local arrays and stack David Brown <david.brown@hesbynett.no> - 2015-03-24 10:28 +0100
                Re: local arrays and stack Bartc <bc@freeuk.com> - 2015-03-24 10:44 +0000
                Re: local arrays and stack Martin Shobe <martin.shobe@yahoo.com> - 2015-03-24 06:38 -0500
                Re: local arrays and stack Martin Shobe <martin.shobe@yahoo.com> - 2015-03-24 09:57 -0500
                Re: local arrays and stack David Brown <david.brown@hesbynett.no> - 2015-03-24 13:22 +0100
                Re: local arrays and stack Bartc <bc@freeuk.com> - 2015-03-25 16:07 +0000
                Re: local arrays and stack David Brown <david.brown@hesbynett.no> - 2015-03-25 17:42 +0100
                Re: local arrays and stack Bartc <bc@freeuk.com> - 2015-03-25 19:06 +0000
                Re: local arrays and stack fir <profesor.fir@gmail.com> - 2015-03-25 12:26 -0700
                Re: local arrays and stack fir <profesor.fir@gmail.com> - 2015-03-25 13:20 -0700
                Re: local arrays and stack Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-03-25 12:28 -0700
                Re: local arrays and stack David Brown <david.brown@hesbynett.no> - 2015-03-25 21:45 +0100
                Re: local arrays and stack Keith Thompson <kst-u@mib.org> - 2015-03-25 12:50 -0700
                Re: local arrays and stack Bartc <bc@freeuk.com> - 2015-03-25 22:33 +0000
                Re: local arrays and stack David Brown <david.brown@hesbynett.no> - 2015-03-25 23:57 +0100
                Re: local arrays and stack David Brown <david.brown@hesbynett.no> - 2015-03-25 21:42 +0100
                Re: local arrays and stack fir <profesor.fir@gmail.com> - 2015-03-25 09:55 -0700
                Re: local arrays and stack Keith Thompson <kst-u@mib.org> - 2015-03-25 12:36 -0700
                Re: local arrays and stack fir <profesor.fir@gmail.com> - 2015-03-25 13:04 -0700
                Re: local arrays and stack David Brown <david.brown@hesbynett.no> - 2015-03-25 21:52 +0100
                Re: local arrays and stack Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-03-25 15:18 -0700
                Re: local arrays and stack David Brown <david.brown@hesbynett.no> - 2015-03-26 00:02 +0100
                Re: local arrays and stack Melzzzzz <mel@zzzzz.com> - 2015-03-26 00:47 +0100
                Re: local arrays and stack Mel <mel@zzzzz.com> - 2015-03-24 14:58 +0100
                Re: local arrays and stack Xcott Craver <xcottcraver@gmail.com> - 2015-03-24 06:58 -0700
                Re: local arrays and stack Keith Thompson <kst-u@mib.org> - 2015-03-23 14:34 -0700
                Re: local arrays and stack David Brown <david.brown@hesbynett.no> - 2015-03-24 10:16 +0100
                Re: local arrays and stack David Brown <david.brown@hesbynett.no> - 2015-03-24 09:55 +0100
                Re: local arrays and stack Noob <root@127.0.0.1> - 2015-03-24 10:23 +0100
                Re: local arrays and stack Tim Rentsch <txr@alumni.caltech.edu> - 2015-03-24 12:18 -0700
                Re: local arrays and stack Keith Thompson <kst-u@mib.org> - 2015-03-24 13:42 -0700
                Re: local arrays and stack Tim Rentsch <txr@alumni.caltech.edu> - 2015-03-25 08:47 -0700
            Re: local arrays and stack Xcott Craver <xcottcraver@gmail.com> - 2015-03-23 09:32 -0700
              Re: local arrays and stack fir <profesor.fir@gmail.com> - 2015-03-23 09:57 -0700
              Re: local arrays and stack Keith Thompson <kst-u@mib.org> - 2015-03-23 10:37 -0700
                Re: local arrays and stack Xcott Craver <xcottcraver@gmail.com> - 2015-03-23 10:49 -0700
                Re: local arrays and stack Keith Thompson <kst-u@mib.org> - 2015-03-23 12:48 -0700
                Re: local arrays and stack jt@toerring.de (Jens Thoms Toerring) - 2015-03-23 22:29 +0000
                Re: local arrays and stack James Kuyper <jameskuyper@verizon.net> - 2015-03-23 19:03 -0400
                Re: local arrays and stack jt@toerring.de (Jens Thoms Toerring) - 2015-03-23 23:36 +0000
                Re: local arrays and stack fir <profesor.fir@gmail.com> - 2015-03-24 02:17 -0700
                Re: local arrays and stack Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-03-23 11:56 -0700
          Re: local arrays and stack Robert Wessel <robertwessel2@yahoo.com> - 2015-03-23 20:00 -0500
            Re: local arrays and stack David Brown <david.brown@hesbynett.no> - 2015-03-24 10:39 +0100

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