Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.c > #59063

Re: Lexical Variables In C Loops (As Compared To Perl Loops)

Show all headers | View raw

Robbie Hatley <see.my.sig@for.my.address> writes:
[...]
> Whereas in C, there's no refs and no ref counts, and "auto"
> variables declared at the top of loop blocks are reused each
> iteration, and are not usable outside of the loop block in
> which they were declared.

In C, an object declared locally in a loop:

    while (blah) {
        int obj;
        /* ... */
    }

exists only for one iteration of the loop.  Each iteration creates and
then destroys a distinct object named "obj".  (Strictly speaking that
occurs on entry and exit to the block, which is a sub-statement of the
loop.)

In a typical C implementation, the same memory location is likely to be
used for each instance of "obj", and the allocation and deallocation
that occur on each iteration in the abstract machine are likely to be
hoisted to a higher scope as an optimization.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"

Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Lexical Variables In C Loops (As Compared To Perl Loops) Robbie Hatley <see.my.sig@for.my.address> - 2015-03-21 00:52 -0700
  Re: Lexical Variables In C Loops (As Compared To Perl Loops) Richard Heathfield <rjh@cpax.org.uk> - 2015-03-21 08:28 +0000
    Re: Lexical Variables In C Loops (As Compared To Perl Loops) Robbie Hatley <see.my.sig@for.my.address> - 2015-03-26 20:57 -0700
  Re: Lexical Variables In C Loops (As Compared To Perl Loops) Keith Thompson <kst-u@mib.org> - 2015-03-21 01:29 -0700
    Re: Lexical Variables In C Loops (As Compared To Perl Loops) Robbie Hatley <see.my.sig@for.my.address> - 2015-03-26 21:01 -0700
  Lexical Variables In C Loops (As Compared To Perl Loops) asetofsymbols@gmail.com - 2015-03-21 01:40 -0700
  Re: Lexical Variables In C Loops (As Compared To Perl Loops) jt@toerring.de (Jens Thoms Toerring) - 2015-03-21 08:43 +0000
    Re: Lexical Variables In C Loops (As Compared To Perl Loops) Robbie Hatley <see.my.sig@for.my.address> - 2015-03-26 20:58 -0700
      Re: Lexical Variables In C Loops (As Compared To Perl Loops) Richard Heathfield <rjh@cpax.org.uk> - 2015-03-27 06:12 +0000
      Re: Lexical Variables In C Loops (As Compared To Perl Loops) Keith Thompson <kst-u@mib.org> - 2015-03-26 23:32 -0700
  Re: Lexical Variables In C Loops (As Compared To Perl Loops) Bartc <bc@freeuk.com> - 2015-03-21 10:54 +0000
    Re: Lexical Variables In C Loops (As Compared To Perl Loops) Keith Thompson <kst-u@mib.org> - 2015-03-21 13:54 -0700
    Re: Lexical Variables In C Loops (As Compared To Perl Loops) Robbie Hatley <see.my.sig@for.my.address> - 2015-03-26 21:24 -0700
      Re: Lexical Variables In C Loops (As Compared To Perl Loops) glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-03-27 20:35 +0000
      Re: Lexical Variables In C Loops (As Compared To Perl Loops) Bartc <bc@freeuk.com> - 2015-03-27 21:24 +0000
        Re: Lexical Variables In C Loops (As Compared To Perl Loops) glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-03-28 00:03 +0000
          Re: Lexical Variables In C Loops (As Compared To Perl Loops) Bartc <bc@freeuk.com> - 2015-03-28 10:00 +0000
        Re: Lexical Variables In C Loops (As Compared To Perl Loops) Stephen Sprunk <stephen@sprunk.org> - 2015-03-28 18:14 -0500
  Re: Lexical Variables In C Loops (As Compared To Perl Loops) Kaz Kylheku <kaz@kylheku.com> - 2015-03-21 14:39 +0000
  Re: Lexical Variables In C Loops (As Compared To Perl Loops) fir <profesor.fir@gmail.com> - 2015-03-21 09:40 -0700
  Re: Lexical Variables In C Loops (As Compared To Perl Loops) James Kuyper <jameskuyper@verizon.net> - 2015-03-21 12:43 -0400
    Re: Lexical Variables In C Loops (As Compared To Perl Loops) Philip Lantz <prl@canterey.us> - 2015-03-21 13:01 -0700
      Re: Lexical Variables In C Loops (As Compared To Perl Loops) James Kuyper <jameskuyper@verizon.net> - 2015-03-22 18:47 -0400
        Re: Lexical Variables In C Loops (As Compared To Perl Loops) Keith Thompson <kst-u@mib.org> - 2015-03-22 16:39 -0700
          Re: Lexical Variables In C Loops (As Compared To Perl Loops) James Kuyper <jameskuyper@verizon.net> - 2015-03-22 20:08 -0400
            Re: Lexical Variables In C Loops (As Compared To Perl Loops) Robbie Hatley <see.my.sig@for.my.address> - 2015-03-26 22:36 -0700
              Re: Lexical Variables In C Loops (As Compared To Perl Loops) Keith Thompson <kst-u@mib.org> - 2015-03-26 23:40 -0700
        Re: Lexical Variables In C Loops (As Compared To Perl Loops) Robbie Hatley <see.my.sig@for.my.address> - 2015-03-26 22:26 -0700
          Re: Lexical Variables In C Loops (As Compared To Perl Loops) Keith Thompson <kst-u@mib.org> - 2015-03-26 23:38 -0700

csiph-web