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Groups > comp.lang.c > #112614
| From | Keith Thompson <kst-u@mib.org> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Null pointer constant |
| Date | 2017-06-19 12:24 -0700 |
| Organization | None to speak of |
| Message-ID | <lnfuevg4qn.fsf@kst-u.example.com> (permalink) |
| References | (1 earlier) <slrn3vfsokdqhs.r2.ike@iceland.freeshell.org> <jMD1B.215949$gM7.179726@fx44.am4> <oi78on$hu7$1@dont-email.me> <9zM1B.193976$KK7.183000@fx12.am4> <oi89cl$t3d$1@dont-email.me> |
David Brown <david.brown@hesbynett.no> writes:
[...]
> In the second case, you have a conditional operator. Look at the rules
> in 6.5.15. There is no option for both the "b" and "c" parts of a?b:c
> to be null pointer constants (perhaps because that would be a useless
> expression).
No, it's because all such cases are already covered.
A null pointer constant is either an expression of integer type, or an
expression of type void*.
If the second and third operands of a conditional operator are both null
pointer constants, there are 3 cases to consider. If both are of
integer type, or if both are of type void*, then that's already covered
by the existing cases in 6.5.15p3. If one is is of integer type and the
other is of type void*, that's covered by the 5th bullet:
- one operand is a pointer and the other is a null pointer constant
In the case of `cond ? 0 : (void*)0`,the "one operand" is (void*)0,
which is a pointer, and the "other" is 0, which is a null pointer
constant. (I'm reading the phrase "a pointer" as "an expression of
pointer type", which IMHO is how it should have been written.)
--
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"
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Null pointer constant bartc <bc@freeuk.com> - 2017-06-18 17:15 +0100
Re: Null pointer constant Keith Thompson <kst-u@mib.org> - 2017-06-18 11:20 -0700
Re: Null pointer constant Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-18 19:23 +0100
Re: Null pointer constant bartc <bc@freeuk.com> - 2017-06-18 20:57 +0100
Re: Null pointer constant Keith Thompson <kst-u@mib.org> - 2017-06-18 13:38 -0700
Re: Null pointer constant Tim Rentsch <txr@alumni.caltech.edu> - 2017-06-19 04:35 -0700
Re: Null pointer constant Nick Bowler <nbowler@draconx.ca> - 2017-06-19 18:08 +0000
Re: Null pointer constant Tim Rentsch <txr@alumni.caltech.edu> - 2017-06-19 21:05 -0700
Re: Null pointer constant Keith Thompson <kst-u@mib.org> - 2017-06-19 12:12 -0700
Re: Null pointer constant Tim Rentsch <txr@alumni.caltech.edu> - 2017-06-19 21:08 -0700
Re: Null pointer constant Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-19 00:34 +0100
Re: Null pointer constant Tim Rentsch <txr@alumni.caltech.edu> - 2017-06-19 04:45 -0700
Re: Null pointer constant David Brown <david.brown@hesbynett.no> - 2017-06-19 13:55 +0200
Re: Null pointer constant bartc <bc@freeuk.com> - 2017-06-19 13:16 +0100
Re: Null pointer constant Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-19 16:58 +0100
Re: Null pointer constant Ike Naar <ike@iceland.freeshell.org> - 2017-06-18 20:58 +0000
Re: Null pointer constant bartc <bc@freeuk.com> - 2017-06-19 00:11 +0100
Re: Null pointer constant David Brown <david.brown@hesbynett.no> - 2017-06-19 03:21 +0200
Re: Null pointer constant bartc <bc@freeuk.com> - 2017-06-19 10:11 +0100
Re: Null pointer constant David Brown <david.brown@hesbynett.no> - 2017-06-19 12:38 +0200
Re: Null pointer constant bartc <bc@freeuk.com> - 2017-06-19 13:05 +0100
Re: Null pointer constant David Brown <david.brown@hesbynett.no> - 2017-06-19 14:39 +0200
Re: Null pointer constant "James R. Kuyper" <jameskuyper@verizon.net> - 2017-06-19 11:06 -0400
Re: Null pointer constant Ike Naar <ike@iceland.freeshell.org> - 2017-06-19 15:51 +0000
Re: Null pointer constant "James R. Kuyper" <jameskuyper@verizon.net> - 2017-06-19 12:22 -0400
Re: Null pointer constant Ike Naar <ike@iceland.freeshell.org> - 2017-06-19 17:29 +0000
Re: Null pointer constant "James R. Kuyper" <jameskuyper@verizon.net> - 2017-06-19 13:45 -0400
Re: Null pointer constant Keith Thompson <kst-u@mib.org> - 2017-06-19 12:31 -0700
Re: Null pointer constant Ike Naar <ike@iceland.freeshell.org> - 2017-06-19 15:10 +0000
Re: Null pointer constant Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-19 16:53 +0100
Re: Null pointer constant "James R. Kuyper" <jameskuyper@verizon.net> - 2017-06-19 13:06 -0400
Re: Null pointer constant Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-19 20:03 +0100
Re: Null pointer constant David Brown <david.brown@hesbynett.no> - 2017-06-19 22:37 +0200
Re: Null pointer constant Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-19 22:10 +0100
Re: Null pointer constant Keith Thompson <kst-u@mib.org> - 2017-06-19 14:25 -0700
Re: Null pointer constant Tim Rentsch <txr@alumni.caltech.edu> - 2017-06-19 22:46 -0700
Re: Null pointer constant Keith Thompson <kst-u@mib.org> - 2017-06-20 08:43 -0700
Re: Null pointer constant supercat@casperkitty.com - 2017-06-20 09:17 -0700
Re: Null pointer constant Tim Rentsch <txr@alumni.caltech.edu> - 2017-06-21 00:56 -0700
Re: Null pointer constant Keith Thompson <kst-u@mib.org> - 2017-06-21 10:07 -0700
Re: Null pointer constant Tim Rentsch <txr@alumni.caltech.edu> - 2017-06-21 23:52 -0700
Re: Null pointer constant Keith Thompson <kst-u@mib.org> - 2017-06-22 10:12 -0700
Re: Null pointer constant Tim Rentsch <txr@alumni.caltech.edu> - 2017-06-22 17:33 -0700
Re: Null pointer constant supercat@casperkitty.com - 2017-06-23 08:54 -0700
Re: Null pointer constant Manfred <invalid@invalid.add> - 2017-06-20 00:00 +0200
Re: Null pointer constant Keith Thompson <kst-u@mib.org> - 2017-06-19 15:27 -0700
Re: Null pointer constant supercat@casperkitty.com - 2017-06-19 16:38 -0700
Re: Null pointer constant Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-20 01:14 +0100
Re: Null pointer constant Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-20 12:03 +0100
Re: Null pointer constant Manfred <noname@invalid.add> - 2017-06-20 13:16 +0200
Re: Null pointer constant jameskuyper@verizon.net - 2017-06-20 05:34 -0700
Re: Null pointer constant Keith Thompson <kst-u@mib.org> - 2017-06-20 08:49 -0700
Re: Null pointer constant Ike Naar <ike@iceland.freeshell.org> - 2017-06-20 16:35 +0000
Re: Null pointer constant "James R. Kuyper" <jameskuyper@verizon.net> - 2017-06-20 13:07 -0400
Re: Null pointer constant Nick Bowler <nbowler@draconx.ca> - 2017-06-20 17:29 +0000
Re: Null pointer constant "James R. Kuyper" <jameskuyper@verizon.net> - 2017-06-20 13:55 -0400
Re: Null pointer constant Nick Bowler <nbowler@draconx.ca> - 2017-06-20 18:06 +0000
Re: Null pointer constant "James R. Kuyper" <jameskuyper@verizon.net> - 2017-06-20 14:42 -0400
Re: Null pointer constant Nick Bowler <nbowler@draconx.ca> - 2017-06-20 19:10 +0000
Re: Null pointer constant Ike Naar <ike@iceland.freeshell.org> - 2017-06-20 18:31 +0000
Re: Null pointer constant Nick Bowler <nbowler@draconx.ca> - 2017-06-20 18:36 +0000
Re: Null pointer constant "James R. Kuyper" <jameskuyper@verizon.net> - 2017-06-20 14:45 -0400
Re: Null pointer constant Nick Bowler <nbowler@draconx.ca> - 2017-06-20 17:14 +0000
Re: Null pointer constant Keith Thompson <kst-u@mib.org> - 2017-06-20 11:55 -0700
Re: Null pointer constant Nick Bowler <nbowler@draconx.ca> - 2017-06-20 19:23 +0000
Re: Null pointer constant "James R. Kuyper" <jameskuyper@verizon.net> - 2017-06-20 15:39 -0400
Re: Null pointer constant scott@slp53.sl.home (Scott Lurndal) - 2017-06-21 13:44 +0000
Re: Null pointer constant scott@slp53.sl.home (Scott Lurndal) - 2017-06-21 13:49 +0000
Re: Null pointer constant Tim Rentsch <txr@alumni.caltech.edu> - 2017-06-21 23:57 -0700
Re: Null pointer constant Philip Lantz <prl@canterey.us> - 2017-06-28 20:04 -0700
Re: Null pointer constant Tim Rentsch <txr@alumni.caltech.edu> - 2017-07-10 08:38 -0700
Re: Null pointer constant Keith Thompson <kst-u@mib.org> - 2017-06-20 12:39 -0700
Re: Null pointer constant bartc <bc@freeuk.com> - 2017-06-20 20:53 +0100
Re: Null pointer constant Keith Thompson <kst-u@mib.org> - 2017-06-20 13:07 -0700
Re: Null pointer constant Nick Bowler <nbowler@draconx.ca> - 2017-06-20 20:50 +0000
Re: Null pointer constant Keith Thompson <kst-u@mib.org> - 2017-06-20 15:35 -0700
Re: Null pointer constant Tim Rentsch <txr@alumni.caltech.edu> - 2017-06-21 00:26 -0700
Re: Null pointer constant Keith Thompson <kst-u@mib.org> - 2017-06-21 09:54 -0700
Re: Null pointer constant "James R. Kuyper" <jameskuyper@verizon.net> - 2017-06-21 13:09 -0400
Re: Null pointer constant Tim Rentsch <txr@alumni.caltech.edu> - 2017-06-22 00:53 -0700
Re: Null pointer constant bartc <bc@freeuk.com> - 2017-06-21 18:09 +0100
Re: Null pointer constant Tim Rentsch <txr@alumni.caltech.edu> - 2017-06-22 00:50 -0700
Re: Null pointer constant Keith Thompson <kst-u@mib.org> - 2017-06-19 10:24 -0700
Re: Null pointer constant Tim Rentsch <txr@alumni.caltech.edu> - 2017-06-19 22:32 -0700
Re: Null pointer constant bartc <bc@freeuk.com> - 2017-06-19 19:40 +0100
Re: Null pointer constant Keith Thompson <kst-u@mib.org> - 2017-06-19 12:08 -0700
Re: Null pointer constant bartc <bc@freeuk.com> - 2017-06-19 20:32 +0100
Re: Null pointer constant Keith Thompson <kst-u@mib.org> - 2017-06-19 12:48 -0700
Re: Null pointer constant jameskuyper@verizon.net - 2017-06-19 13:08 -0700
Re: Null pointer constant Nick Bowler <nbowler@draconx.ca> - 2017-06-19 20:40 +0000
Re: Null pointer constant bartc <bc@freeuk.com> - 2017-06-19 22:01 +0100
Re: Null pointer constant supercat@casperkitty.com - 2017-06-19 14:15 -0700
Re: Null pointer constant jameskuyper@verizon.net - 2017-06-19 14:25 -0700
Re: Null pointer constant Ike Naar <ike@iceland.freeshell.org> - 2017-06-19 21:06 +0000
Re: Null pointer constant Keith Thompson <kst-u@mib.org> - 2017-06-19 14:28 -0700
Re: Null pointer constant Ike Naar <ike@iceland.freeshell.org> - 2017-06-19 21:35 +0000
Re: Null pointer constant supercat@casperkitty.com - 2017-06-19 14:48 -0700
Re: Null pointer constant Ike Naar <ike@iceland.freeshell.org> - 2017-06-20 15:38 +0000
Re: Null pointer constant Keith Thompson <kst-u@mib.org> - 2017-06-19 15:16 -0700
Re: Null pointer constant supercat@casperkitty.com - 2017-06-19 14:29 -0700
Re: Null pointer constant Keith Thompson <kst-u@mib.org> - 2017-06-19 15:18 -0700
Re: Null pointer constant Tim Rentsch <txr@alumni.caltech.edu> - 2017-06-19 22:48 -0700
Re: Null pointer constant bartc <bc@freeuk.com> - 2017-06-20 15:09 +0100
Re: Null pointer constant Keith Thompson <kst-u@mib.org> - 2017-06-19 10:19 -0700
Re: Null pointer constant Keith Thompson <kst-u@mib.org> - 2017-06-19 10:15 -0700
Re: Null pointer constant David Brown <david.brown@hesbynett.no> - 2017-06-19 22:44 +0200
Re: Null pointer constant Keith Thompson <kst-u@mib.org> - 2017-06-19 12:24 -0700
Re: Null pointer constant Ike Naar <ike@iceland.freeshell.org> - 2017-06-19 08:21 +0000
Re: Null pointer constant bartc <bc@freeuk.com> - 2017-06-19 10:17 +0100
Re: Null pointer constant Keith Thompson <kst-u@mib.org> - 2017-06-19 10:04 -0700
Re: Null pointer constant Keith Thompson <kst-u@mib.org> - 2017-06-19 12:34 -0700
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