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| From | Keith Thompson <kst-u@mib.org> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Arrays Vs Pointers |
| Date | 2012-02-19 12:21 -0800 |
| Organization | None to speak of |
| Message-ID | <lnfwe6efr8.fsf@nuthaus.mib.org> (permalink) |
| References | <jgs51h$hhm$1@speranza.aioe.org> <slrnjk1qug.1m5e.willem@toad.stack.nl> |
Willem <willem@toad.stack.nl> writes:
> peter wrote:
> ) I am currently exploring the world of pointers and have encounter some
> ) inconsistent information regarding the best way to reference an
> ) array: array[1] OR *(array +1).
> )
> ) One book says that you should not use the syntax array[1] because
> ) of performance reason.
>
> That book is completely and utterly wrong.
> In C, "array[index]" is *exactly the same* as "*(array + index)"
> I would go so far as to call it syntactic sugar.
> Hell, it's even commutative. "array[index]" means the same as "index[array]" !
[...]
Yes, but I doubt that that's what the book actually said. I'm only
guessing, but the book was probably advocating code like this:
void func(char *s) {
while (*s != '\0') {
do_something_with(*s);
s++;
}
}
over this:
void func(char *s) {
size_t i = 0;
while (s[i] != '\0') {
do_something_with(s[i]);
i++;
}
}
The former, by updating the pointer on each iteration, avoids
redoing the index calculation, which might be moderately expenstive,
especially for arrays of something bigger than char.
It's a largely obsolete argument, since modern optimizing compilers can
generate the same code for both, but it's not "completely and utterly
wrong".
I'd be interested in knowing which book the previous poster was
referring to, how old it is, and what it actually says.
--
Keith Thompson (The_Other_Keith) kst-u@mib.org <http://www.ghoti.net/~kst>
Will write code for food.
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"
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Arrays Vs Pointers peter <pc722@nospam.mail.com.br> - 2012-02-07 21:28 +0000
Re: Arrays Vs Pointers William Ahern <william@wilbur.25thandClement.com> - 2012-02-07 13:50 -0800
Re: Arrays Vs Pointers James Kuyper <jameskuyper@verizon.net> - 2012-02-07 17:13 -0500
Re: Arrays Vs Pointers Stephen Sprunk <stephen@sprunk.org> - 2012-02-07 16:38 -0600
Re: Arrays Vs Pointers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-02-07 23:09 +0000
Re: Arrays Vs Pointers Keith Thompson <kst-u@mib.org> - 2012-02-07 14:41 -0800
Re: Arrays Vs Pointers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-02-07 23:07 +0000
Re: Arrays Vs Pointers James Kuyper <jameskuyper@verizon.net> - 2012-02-07 19:14 -0500
Re: Arrays Vs Pointers Shao Miller <sha0.miller@gmail.com> - 2012-02-07 18:21 -0500
Re: Arrays Vs Pointers Keith Thompson <kst-u@mib.org> - 2012-02-07 16:25 -0800
Re: Arrays Vs Pointers Shao Miller <sha0.miller@gmail.com> - 2012-02-07 20:31 -0500
Re: Arrays Vs Pointers Ike Naar <ike@sverige.freeshell.org> - 2012-02-07 23:36 +0000
Re: Arrays Vs Pointers Keith Thompson <kst-u@mib.org> - 2012-02-07 16:26 -0800
Re: Arrays Vs Pointers Keith Thompson <kst-u@mib.org> - 2012-02-07 16:24 -0800
Re: Arrays Vs Pointers Paul N <gw7rib@aol.com> - 2012-02-07 14:55 -0800
Re: Arrays Vs Pointers Shao Miller <sha0.miller@gmail.com> - 2012-02-07 18:11 -0500
Re: Arrays Vs Pointers John Bode <jfbode1029@gmail.com> - 2012-02-08 16:06 -0800
Re: Arrays Vs Pointers Philip Lantz <prl@canterey.us> - 2012-02-08 23:25 -0800
Re: Arrays Vs Pointers John Bode <jfbode1029@gmail.com> - 2012-02-09 05:34 -0800
Re: Arrays Vs Pointers Philip Lantz <prl@canterey.us> - 2012-02-10 01:04 -0800
Re: Arrays Vs Pointers Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-02-09 00:20 -0800
Re: Arrays Vs Pointers 88888 Dihedral <dihedral88888@googlemail.com> - 2012-02-09 23:42 -0800
Re: Arrays Vs Pointers gwowen <gwowen@gmail.com> - 2012-02-10 01:20 -0800
Re: Arrays Vs Pointers David Thompson <dave.thompson2@verizon.net> - 2012-02-18 23:12 -0500
Re: Arrays Vs Pointers Kaz Kylheku <kaz@kylheku.com> - 2012-02-19 05:53 +0000
Re: Arrays Vs Pointers Markus Wichmann <nullplan@gmx.net> - 2012-02-19 18:54 +0100
Re: Arrays Vs Pointers Willem <willem@toad.stack.nl> - 2012-02-19 18:51 +0000
Re: Arrays Vs Pointers "io_x" <a@b.c.invalid> - 2012-02-19 21:29 +0100
Re: Arrays Vs Pointers Markus Wichmann <nullplan@gmx.net> - 2012-02-20 11:24 +0100
Re: Arrays Vs Pointers gwowen <gwowen@gmail.com> - 2012-02-21 01:51 -0800
Re: Arrays Vs Pointers Willem <willem@toad.stack.nl> - 2012-02-19 12:32 +0000
Re: Arrays Vs Pointers Keith Thompson <kst-u@mib.org> - 2012-02-19 12:21 -0800
Re: Arrays Vs Pointers Willem <willem@toad.stack.nl> - 2012-02-19 21:00 +0000
Re: Arrays Vs Pointers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-02-19 21:42 +0000
Re: Arrays Vs Pointers pete <pfiland@mindspring.com> - 2012-02-20 17:32 -0500
Re: Arrays Vs Pointers James Kuyper <jameskuyper@verizon.net> - 2012-02-20 17:56 -0500
Re: Arrays Vs Pointers Keith Thompson <kst-u@mib.org> - 2012-02-20 15:19 -0800
Re: Arrays Vs Pointers Keith Thompson <kst-u@mib.org> - 2012-02-20 16:35 -0800
Re: Arrays Vs Pointers pete <pfiland@mindspring.com> - 2012-02-20 22:53 -0500
Re: Arrays Vs Pointers Keith Thompson <kst-u@mib.org> - 2012-02-20 21:16 -0800
Re: Arrays Vs Pointers Richard Sanders <lnr729@gmail.com> - 2012-02-21 00:26 -0800
Re: Arrays Vs Pointers pete <pfiland@mindspring.com> - 2012-02-21 11:46 -0500
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