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| From | James Kuyper <jameskuyper@verizon.net> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: c prog -plz explain |
| Date | 2014-03-12 11:36 -0400 |
| Organization | A noiseless patient Spider |
| Message-ID | <lfput3$n8p$1@dont-email.me> (permalink) |
| References | (4 earlier) <20140310235955.176@kylheku.com> <lfpa7b$150$1@dont-email.me> <20140312073525.267@kylheku.com> <lfpsig$4ic$2@dont-email.me> <lfptob$eeu$1@dont-email.me> |
On 03/12/2014 11:16 AM, Eric Sosman wrote:
> On 3/12/2014 10:56 AM, Noob wrote:
...
>> I realize now that I only considered "pointer" casts.
>> [...]
>> Perhaps the rule should be "Don't use pointer casts anywhere"
>> [...]
>> Do you have other examples of reasonable use of casts?
>
> How about converting between a struct pointer and a pointer
> to the struct's first element?
In one direction, there's a perfectly safe alternative:
&struct_pointer->first_member (unless the struct has an opaque type -
but it really shouldn't have an opaque type in any code that is going to
try to access it's members). It's only going in the other direction that
requires a cast.
> How about implementing a comparator function for qsort() or
> bsearch()? Personally, I prefer to introduce a couple helper
> variables:
>
> int compare(const void *pp, const void *qq) {
> const struct whatnot *p = pp, *q = qq;
> return strcmp(p->name, q->name);
> }
>
> ... but doing without the extra variables and applying casts
> to the arguments would be perfectly reasonable.
Because I prefer to treat casts as danger signs, I also prefer using the
the helper variables.
--
James Kuyper
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c prog -plz explain SAHIL MAHLA <sahilmehla@gmail.com> - 2014-03-10 14:50 -0700
Re: c prog -plz explain Keith Thompson <kst-u@mib.org> - 2014-03-10 15:41 -0700
Re: c prog -plz explain Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-03-10 23:21 +0000
Re: c prog -plz explain Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-03-10 23:24 +0000
Re: c prog -plz explain SAHIL MAHLA <sahilmehla@gmail.com> - 2014-03-10 20:28 -0700
Re: c prog -plz explain James Kuyper <jameskuyper@verizon.net> - 2014-03-11 00:15 -0400
Re: c prog -plz explain Kaz Kylheku <kaz@kylheku.com> - 2014-03-11 07:12 +0000
Re: c prog -plz explain Noob <root@127.0.0.1> - 2014-03-12 10:43 +0100
Re: c prog -plz explain Kaz Kylheku <kaz@kylheku.com> - 2014-03-12 14:38 +0000
Re: c prog -plz explain Noob <root@127.0.0.1> - 2014-03-12 15:56 +0100
Re: c prog -plz explain Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-03-12 11:16 -0400
Re: c prog -plz explain James Kuyper <jameskuyper@verizon.net> - 2014-03-12 11:36 -0400
Re: c prog -plz explain Kaz Kylheku <kaz@kylheku.com> - 2014-03-12 15:38 +0000
Re: c prog -plz explain glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-03-12 19:13 +0000
Re: c prog -plz explain Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-03-12 16:05 -0400
Re: c prog -plz explain James Kuyper <jameskuyper@verizon.net> - 2014-03-12 16:32 -0400
Re: c prog -plz explain Ian Collins <ian-news@hotmail.com> - 2014-03-13 09:38 +1300
Re: c prog -plz explain Tim Rentsch <txr@alumni.caltech.edu> - 2014-03-29 08:32 -0700
Re: c prog -plz explain glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-03-12 19:03 +0000
Re: c prog -plz explain James Kuyper <jameskuyper@verizon.net> - 2014-03-12 15:33 -0400
Re: c prog -plz explain Kaz Kylheku <kaz@kylheku.com> - 2014-03-12 20:56 +0000
Re: c prog -plz explain Ian Collins <ian-news@hotmail.com> - 2014-03-13 10:07 +1300
Re: c prog -plz explain "BartC" <bc@freeuk.com> - 2014-03-11 10:33 +0000
Re: c prog -plz explain Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2014-03-10 18:48 -0400
Re: c prog -plz explain SAHIL MAHLA <sahilmehla@gmail.com> - 2014-03-10 20:26 -0700
Re: c prog -plz explain Ian Collins <ian-news@hotmail.com> - 2014-03-11 16:34 +1300
typecasting (was Re: c prog -plz explain) Jorgen Grahn <grahn+nntp@snipabacken.se> - 2014-03-12 07:03 +0000
Re: typecasting (was Re: c prog -plz explain) Kaz Kylheku <kaz@kylheku.com> - 2014-03-12 07:40 +0000
Re: typecasting (was Re: c prog -plz explain) Lowell Gilbert <lgusenet@be-well.ilk.org> - 2014-03-12 10:47 -0400
Re: typecasting (was Re: c prog -plz explain) Ken Brody <kenbrody@spamcop.net> - 2014-03-12 13:01 -0400
Re: typecasting (was Re: c prog -plz explain) Richard <rgrdev_@gmail.com> - 2014-03-12 12:47 +0100
Re: typecasting (was Re: c prog -plz explain) gazelle@shell.xmission.com (Kenny McCormack) - 2014-03-12 12:39 +0000
Re: typecasting (was Re: c prog -plz explain) Kaz Kylheku <kaz@kylheku.com> - 2014-03-12 15:06 +0000
Re: c prog -plz explain Kaz Kylheku <kaz@kylheku.com> - 2014-03-11 07:26 +0000
Re: c prog -plz explain Richard <rgrdev_@gmail.com> - 2014-03-11 08:39 +0100
Re: c prog -plz explain Kaz Kylheku <kaz@kylheku.com> - 2014-03-11 08:08 +0000
Re: c prog -plz explain Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2014-03-11 09:14 -0400
Re: c prog -plz explain Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-03-11 15:38 +0000
Re: c prog -plz explain Ken Brody <kenbrody@spamcop.net> - 2014-03-11 12:53 -0400
Re: c prog -plz explain Keith Thompson <kst-u@mib.org> - 2014-03-11 11:47 -0700
Re: c prog -plz explain glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-03-11 21:41 +0000
Re: c prog -plz explain Kaz Kylheku <kaz@kylheku.com> - 2014-03-11 22:01 +0000
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