Re: about NULL as a parameter to a libc function

From	Phil Carmody <thefatphil_demunged@yahoo.co.uk>
Newsgroups	comp.lang.c
Subject	Re: about NULL as a parameter to a libc function
Date	2011-10-29 15:11 +0300
Organization	A noiseless patient Spider
Message-ID	<8739ecm1z8.fsf@bazspaz.fatphil.org> (permalink)
References	<14abde31-4573-45e7-bdaf-eb70b22741d7@z28g2000pro.googlegroups.com> <j8drvi$41k$1@dont-email.me> <lnty6slt00.fsf@nuthaus.mib.org>

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Keith Thompson <kst-u@mib.org> writes:
> Mark Bluemel <mark_bluemel@pobox.com> writes:
> > On 10/28/2011 09:49 AM, gaoqiang wrote:
> >> a good function should deal with unwanted parameters.
> >
> > That's one point of view. Another point of view is that code should 
> > abide by the contract of the api and pass the appropriate arguments to 
> > to functions.
> >
> >> why memcpy,strcmp .etc ,these libc functions, do not
> >> accept NULL pointer ? called with NULL, just get  segment
> >> fault.  for efficiency ?
> >
> > For example, my man page for strcmp states "The strcmp() function 
> > compares the two strings s1 and s2" - a NULL pointer isn't a string, so 
> > why should the function deal with it?
> 
> Mine says the same thing -- and it's wrong.  It compares the strings
> *pointed to by* s1 and s2.  (Yes, the meaning is clear enough,
> but it's potentially misleading to inexperienced C programmers who
> might thing that strings are really pointers.)

I think you've mentioned this flub before on c.l.c. Did you raise it
with c.s.c, or even members of the committee themselves? It's an easy
fix that doesn't need to harm readability, so it would be good if it
was pushed forwards. (One lazy hack fix is to add a "sometimes as
shorthand a pointer to a string will be refered to as a string"
disclaimer at definition time, but that's perhaps too much an
admission of sloppiness.)

Phil
-- 
Unix is simple. It just takes a genius to understand its simplicity
-- Dennis Ritchie (1941-2011), Unix Co-Creator

Thread

about NULL as a parameter to a libc function gaoqiang <gaoqiangscut@gmail.com> - 2011-10-28 01:49 -0700
  Re: about NULL as a parameter to a libc function Mark Bluemel <mark_bluemel@pobox.com> - 2011-10-28 10:14 +0100
    Re: about NULL as a parameter to a libc function gaoqiang <gaoqiangscut@gmail.com> - 2011-10-28 03:22 -0700
      Re: about NULL as a parameter to a libc function Mark Bluemel <mark_bluemel@pobox.com> - 2011-10-28 11:29 +0100
        Re: about NULL as a parameter to a libc function Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-10-29 07:08 +0000
      Re: about NULL as a parameter to a libc function James Kuyper <jameskuyper@verizon.net> - 2011-10-28 07:05 -0400
      Re: about NULL as a parameter to a libc function Keith Thompson <kst-u@mib.org> - 2011-10-28 14:15 -0700
      Re: about NULL as a parameter to a libc function gordonb.4o15x@burditt.org (Gordon Burditt) - 2011-10-28 16:36 -0500
        Re: about NULL as a parameter to a libc function Robert Wessel <robertwessel2@yahoo.com> - 2011-10-28 17:30 -0500
          Re: about NULL as a parameter to a libc function jgharston <jgh@arcade.demon.co.uk> - 2011-10-31 10:40 -0700
      Re: about NULL as a parameter to a libc function Kaz Kylheku <kaz@kylheku.com> - 2011-10-28 22:32 +0000
      Re: about NULL as a parameter to a libc function Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-10-29 06:20 -0700
        Re: about NULL as a parameter to a libc function "BartC" <bc@freeuk.com> - 2011-10-29 15:40 +0100
          Re: about NULL as a parameter to a libc function Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-10-30 08:05 -0700
    Re: about NULL as a parameter to a libc function Keith Thompson <kst-u@mib.org> - 2011-10-28 14:13 -0700
      Re: about NULL as a parameter to a libc function Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-10-29 15:11 +0300
        Re: about NULL as a parameter to a libc function Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-10-29 06:41 -0700
        Re: about NULL as a parameter to a libc function Keith Thompson <kst-u@mib.org> - 2011-10-29 11:29 -0700
  Re: about NULL as a parameter to a libc function Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-10-28 02:36 -0700
    Re: about NULL as a parameter to a libc function Mike Manilone <mike@laptop.mike> - 2011-10-28 12:58 +0000
      Re: about NULL as a parameter to a libc function James Kuyper <jameskuyper@verizon.net> - 2011-10-28 11:00 -0400
        Re: about NULL as a parameter to a libc function Kenneth Brody <kenbrody@spamcop.net> - 2011-11-03 11:13 -0400
      Re: about NULL as a parameter to a libc function Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-10-29 06:37 -0700
      Re: about NULL as a parameter to a libc function Kenneth Brody <kenbrody@spamcop.net> - 2011-11-03 11:00 -0400
        Re: about NULL as a parameter to a libc function James Kuyper <jameskuyper@verizon.net> - 2011-11-03 12:54 -0400
          Re: about NULL as a parameter to a libc function Kaz Kylheku <kaz@kylheku.com> - 2011-11-03 17:08 +0000
            Re: about NULL as a parameter to a libc function James Kuyper <jameskuyper@verizon.net> - 2011-11-03 13:18 -0400
              Re: about NULL as a parameter to a libc function Kaz Kylheku <kaz@kylheku.com> - 2011-11-03 17:28 +0000
                Re: about NULL as a parameter to a libc function James Kuyper <jameskuyper@verizon.net> - 2011-11-03 13:48 -0400
                Re: about NULL as a parameter to a libc function Kaz Kylheku <kaz@kylheku.com> - 2011-11-03 17:55 +0000
                Re: about NULL as a parameter to a libc function James Kuyper <jameskuyper@verizon.net> - 2011-11-03 14:12 -0400
                Re: about NULL as a parameter to a libc function blp@cs.stanford.edu (Ben Pfaff) - 2011-11-03 11:22 -0700
                Re: about NULL as a parameter to a libc function James Kuyper <jameskuyper@verizon.net> - 2011-11-03 14:28 -0400
                Re: about NULL as a parameter to a libc function Kaz Kylheku <kaz@kylheku.com> - 2011-11-03 19:47 +0000
                Re: about NULL as a parameter to a libc function James Kuyper <jameskuyper@verizon.net> - 2011-11-03 16:19 -0400
                Re: about NULL as a parameter to a libc function Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 22:13 -0800
                Re: about NULL as a parameter to a libc function Ike Naar <ike@sverige.freeshell.org> - 2011-11-03 18:20 +0000
                Re: about NULL as a parameter to a libc function Ike Naar <ike@sverige.freeshell.org> - 2011-11-03 18:34 +0000
                Re: about NULL as a parameter to a libc function Kaz Kylheku <kaz@kylheku.com> - 2011-11-03 19:49 +0000
                Re: about NULL as a parameter to a libc function James Kuyper <jameskuyper@verizon.net> - 2011-11-03 16:21 -0400
                Re: about NULL as a parameter to a libc function Ike Naar <ike@iceland.freeshell.org> - 2011-11-03 22:19 +0000
                Re: about NULL as a parameter to a libc function Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 22:17 -0800
          Re: about NULL as a parameter to a libc function Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 21:19 -0800
    Re: about NULL as a parameter to a libc function Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-10-28 14:26 +0100
      Re: about NULL as a parameter to a libc function Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-10-28 12:46 -0600
      Re: about NULL as a parameter to a libc function Keith Thompson <kst-u@mib.org> - 2011-10-28 14:19 -0700
        Re: about NULL as a parameter to a libc function Keith Thompson <kst-u@mib.org> - 2011-10-28 16:37 -0700
  Re: about NULL as a parameter to a libc function James Kuyper <jameskuyper@verizon.net> - 2011-10-28 07:22 -0400
    Re: about NULL as a parameter to a libc function Kenneth Brody <kenbrody@spamcop.net> - 2011-11-03 10:40 -0400
      Re: about NULL as a parameter to a libc function Kaz Kylheku <kaz@kylheku.com> - 2011-11-03 15:10 +0000
      Re: about NULL as a parameter to a libc function Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-11-04 03:03 +0000
  Re: about NULL as a parameter to a libc function Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-10-28 08:42 -0400
  Re: about NULL as a parameter to a libc function "io_x" <a@b.c.invalid> - 2011-10-28 16:31 +0200
  Re: about NULL as a parameter to a libc function "BartC" <bc@freeuk.com> - 2011-10-28 20:29 +0100
    Re: about NULL as a parameter to a libc function Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-10-29 14:49 +0300
      Re: about NULL as a parameter to a libc function Ike Naar <ike@sverige.freeshell.org> - 2011-10-29 13:41 +0000
  Re: about NULL as a parameter to a libc function John Gordon <gordon@panix.com> - 2011-10-28 19:53 +0000
    Re: about NULL as a parameter to a libc function "BartC" <bc@freeuk.com> - 2011-10-28 21:13 +0100
      Re: about NULL as a parameter to a libc function John Gordon <gordon@panix.com> - 2011-10-28 20:33 +0000
        Re: about NULL as a parameter to a libc function James Kuyper <jameskuyper@verizon.net> - 2011-10-28 16:56 -0400
          Re: about NULL as a parameter to a libc function blp@cs.stanford.edu (Ben Pfaff) - 2011-10-28 14:30 -0700
      Re: about NULL as a parameter to a libc function James Kuyper <jameskuyper@verizon.net> - 2011-10-28 16:45 -0400
      Re: about NULL as a parameter to a libc function Keith Thompson <kst-u@mib.org> - 2011-10-28 15:35 -0700
        Re: about NULL as a parameter to a libc function "BartC" <bc@freeuk.com> - 2011-10-29 13:00 +0100
          Re: about NULL as a parameter to a libc function Keith Thompson <kst-u@mib.org> - 2011-10-29 11:26 -0700
            Re: about NULL as a parameter to a libc function "BartC" <bc@freeuk.com> - 2011-10-29 20:24 +0100
              Re: about NULL as a parameter to a libc function Keith Thompson <kst-u@mib.org> - 2011-10-29 14:03 -0700
      Re: about NULL as a parameter to a libc function Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-10-29 07:30 -0700
      Re: about NULL as a parameter to a libc function Kenneth Brody <kenbrody@spamcop.net> - 2011-11-03 11:26 -0400
        Re: about NULL as a parameter to a libc function James Kuyper <jameskuyper@verizon.net> - 2011-11-03 12:59 -0400
        Re: about NULL as a parameter to a libc function Keith Thompson <kst-u@mib.org> - 2011-11-03 13:42 -0700
  Re: about NULL as a parameter to a libc function Kaz Kylheku <kaz@kylheku.com> - 2011-10-28 20:17 +0000
    Re: about NULL as a parameter to a libc function Richard Damon <news.x.richarddamon@xoxy.net> - 2011-10-28 18:51 -0400
  Re: about NULL as a parameter to a libc function Nobody <nobody@nowhere.com> - 2011-10-28 21:40 +0100
    Re: about NULL as a parameter to a libc function James Kuyper <jameskuyper@verizon.net> - 2011-10-28 17:09 -0400
      Re: about NULL as a parameter to a libc function Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-10-29 15:03 +0300
        Re: about NULL as a parameter to a libc function James Kuyper <jameskuyper@verizon.net> - 2011-10-29 09:42 -0400
    Re: about NULL as a parameter to a libc function Kaz Kylheku <kaz@kylheku.com> - 2011-10-28 21:18 +0000
      Re: about NULL as a parameter to a libc function Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-10-28 23:30 +0100
      Re: about NULL as a parameter to a libc function Keith Thompson <kst-u@mib.org> - 2011-10-28 15:37 -0700
        Re: about NULL as a parameter to a libc function Kaz Kylheku <kaz@kylheku.com> - 2011-10-28 23:47 +0000
          Re: about NULL as a parameter to a libc function Keith Thompson <kst-u@mib.org> - 2011-10-28 17:13 -0700
            Re: about NULL as a parameter to a libc function Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-10-29 04:31 +0100
              Re: about NULL as a parameter to a libc function Kaz Kylheku <kaz@kylheku.com> - 2011-10-29 05:42 +0000
                Re: about NULL as a parameter to a libc function Seebs <usenet-nospam@seebs.net> - 2011-10-30 17:22 +0000
                Re: about NULL as a parameter to a libc function Patrick Scheible <kkt@zipcon.net> - 2011-10-30 23:43 -0700
                Re: about NULL as a parameter to a libc function Robert Wessel <robertwessel2@yahoo.com> - 2011-10-31 05:31 -0500
                Re: about NULL as a parameter to a libc function Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-10-31 12:42 +0200
                Re: about NULL as a parameter to a libc function Robert Wessel <robertwessel2@yahoo.com> - 2011-10-31 13:11 -0500
                Re: about NULL as a parameter to a libc function Seebs <usenet-nospam@seebs.net> - 2011-10-31 17:18 +0000
      Re: about NULL as a parameter to a libc function Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-10-29 07:32 -0700
    Re: about NULL as a parameter to a libc function jacob navia <jacob@spamsink.net> - 2011-10-28 23:41 +0200
      Re: about NULL as a parameter to a libc function Kaz Kylheku <kaz@kylheku.com> - 2011-10-28 22:42 +0000
        Re: about NULL as a parameter to a libc function jacob navia <jacob@spamsink.net> - 2011-10-29 10:09 +0200
          Re: about NULL as a parameter to a libc function Nobody <nobody@nowhere.com> - 2011-10-29 10:11 +0100
            Re: about NULL as a parameter to a libc function Angel <angel+news@spamcop.net> - 2011-10-29 09:42 +0000
            Re: about NULL as a parameter to a libc function jacob navia <jacob@spamsink.net> - 2011-10-29 16:17 +0200
          Re: about NULL as a parameter to a libc function Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-10-29 07:39 -0700
            Re: about NULL as a parameter to a libc function jacob navia <jacob@spamsink.net> - 2011-10-29 19:29 +0200
              Re: about NULL as a parameter to a libc function "io_x" <a@b.c.invalid> - 2011-10-29 20:25 +0200
              Re: about NULL as a parameter to a libc function Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-10-30 08:14 -0700
    Re: about NULL as a parameter to a libc function ImpalerCore <jadill33@gmail.com> - 2011-10-31 18:30 -0700
      Re: about NULL as a parameter to a libc function Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 18:21 -0800
    Re: about NULL as a parameter to a libc function Kenneth Brody <kenbrody@spamcop.net> - 2011-11-03 11:31 -0400
      Re: about NULL as a parameter to a libc function Keith Thompson <kst-u@mib.org> - 2011-11-03 13:45 -0700
  Re: about NULL as a parameter to a libc function Jonathan Leffler <jleffler@earthlink.net> - 2011-10-29 23:41 -0700
    Re: about NULL as a parameter to a libc function James Kuyper <jameskuyper@verizon.net> - 2011-10-30 07:13 -0400

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