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| From | Keith Thompson <kst-u@mib.org> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: sizeof(arr[0]) |
| Date | 2015-06-16 13:18 -0700 |
| Organization | None to speak of |
| Message-ID | <lnd20vmmol.fsf@nuthaus.mib.org> (permalink) |
| References | (9 earlier) <mln8jp$fof$1@dont-email.me> <ea304b74-27ce-4371-a754-80eac3c02d4d@googlegroups.com> <d880c856-c620-47d3-b70f-c2fbe753c5a3@googlegroups.com> <87h9q7y0y0.fsf@bsb.me.uk> <e9818bab-4b08-44d1-8223-327a0e954fcd@googlegroups.com> |
"Rick C. Hodgin" <rick.c.hodgin@gmail.com> writes:
> On Tuesday, June 16, 2015 at 2:15:27 PM UTC-4, Ben Bacarisse wrote:
>> "Rick C. Hodgin" <rick.c.hodgin@gmail.com> writes:
>>
>> > On Tuesday, June 16, 2015 at 12:51:42 PM UTC-4, David Kleinecke wrote:
>> >> One way to think of it is that "sizeof (int)" is the sizeof operator
>> >> acting on a type cast and "sizeof x" is the operator acting on a
>> >> variable (like "& x") - and to forget that "sizeof (x)" is possible.
>> >
>> > It's why sizeof should always be sizeof(), and never sizeof. I feel
>> > the same way about return (it should always be return() rather than
>> > return, and the same for other similar keywords).
>>
>> Do you write long(x); ++(p) and/or *(p) all the time?
>
> Yes. Every time. :-)
>
> No, of course not. But I do write it on things like sizeof(), and
> other similar things because I do look at them as a type of function.
Well there's your problem right there.
'sizeof" is not a function (nor is it a macro). It's an operator
whose symbol happens to be a keyword. It behaves in a number of
ways that are very different from the way functions behave: the
operand is usually not evaluated, the result depends only on the
type of the operand, and so forth.
The only things that's special about `sizeof` relative to other
operators are that (a) its symbol happens to be a keyword rather
than punctuation, and (b) its operand (not argument) can be either
an expression or a parenthesized type name (note that functions
cannot take type names as arguments).
Imagine a language that's identical to C, except that it spells
`sizeof` as `$"` Would you still insist on writing `$(x)`, or
would you be willing to write `$ x` or `$x`?
You can construct a mental model that treats "sizeof" as if it
were a function. If you do so carefully enough, and keep in mind
the special cases that result from the inconsistencies between
that model and reality, you can write consistent and correct code.
But IMHO that's a lot more effort than just learning what "sizeof"
really is. To do it reliably, you have to understand both your
mental model and the actual syntax and semantics of the language,
so you can avoid the inconsistencies.
[...]
> None. There's also no ambiguity in return x; or return result; I
> prefer for it to be return(42);, return(x), and return(result). I
> view those also as functions because I am giving it some input, and
> it is giving me an output (which happens to be the same value, though
> in some cases it is cast through a function, such as "return(2);" when
> 2 must be translated to a float. As such ... function, just one that
> happens to be a compile-time function, rather than runtime.
Similarly, "return" is a keyword, not a function, and it's used
as part of a "return statement", which has its own unique syntax
that's not related to function call syntax.
A return statement, unlike a function call, doesn't yield a result;
you can't write `x = return 42;`. It causes the function in which
it occurs to return a result, which then becomes the value yielded
by the function call expression. *Very* different.
[...]
--
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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sizeof(arr[0]) kuznecov.alexey@gmail.com - 2015-06-10 12:38 -0700
Re: sizeof(arr[0]) James Kuyper <jameskuyper@verizon.net> - 2015-06-10 16:00 -0400
Re: sizeof(arr[0]) kuznecov.alexey@gmail.com - 2015-06-10 14:53 -0700
Re: sizeof(arr[0]) kuznecov.alexey@gmail.com - 2015-06-10 13:11 -0700
Re: sizeof(arr[0]) Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-06-10 21:21 +0100
Re: sizeof(arr[0]) Richard Heathfield <rjh@cpax.org.uk> - 2015-06-10 22:08 +0100
Re: sizeof(arr[0]) Andrew Cooper <amc96@cam.ac.uk> - 2015-06-11 00:27 +0100
Re: sizeof(arr[0]) Richard Heathfield <rjh@cpax.org.uk> - 2015-06-11 00:34 +0100
Re: sizeof(arr[0]) Richard Heathfield <rjh@cpax.org.uk> - 2015-06-11 00:38 +0100
Re: writing code for people who don't know the language (was: sizeof(arr[0])) Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2015-06-10 21:16 -0400
Re: writing code for people who don't know the language Richard Heathfield <rjh@cpax.org.uk> - 2015-06-11 02:35 +0100
Re: writing code for people who don't know the language Bartc <bc@freeuk.com> - 2015-06-11 11:16 +0100
Re: writing code for people who don't know the language Bartc <bc@freeuk.com> - 2015-06-11 11:29 +0100
Re: writing code for people who don't know the language gazelle@shell.xmission.com (Kenny McCormack) - 2015-06-11 11:43 +0000
Re: sizeof(arr[0]) Paul N <gw7rib@aol.com> - 2015-06-14 13:13 -0700
Re: sizeof(arr[0]) Philip Lantz <prl@canterey.us> - 2015-06-14 17:52 -0700
Re: sizeof(arr[0]) "Bill Cunningham" <nospam@nspam.invalid> - 2015-06-15 14:26 -0400
Re: sizeof(arr[0]) Richard Heathfield <rjh@cpax.org.uk> - 2015-06-15 19:34 +0100
Re: sizeof(arr[0]) "Bill Cunningham" <nospam@nspam.invalid> - 2015-06-15 14:55 -0400
Re: sizeof(arr[0]) Melzzzzz <melz@zzzzz.com> - 2015-06-15 20:59 +0200
Re: sizeof(arr[0]) Richard Heathfield <rjh@cpax.org.uk> - 2015-06-15 20:11 +0100
Re: sizeof(arr[0]) "Bill Cunningham" <nospam@nspam.invalid> - 2015-06-15 15:22 -0400
Re: sizeof(arr[0]) David Kleinecke <dkleinecke@gmail.com> - 2015-06-16 09:51 -0700
Re: sizeof(arr[0]) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-06-16 10:51 -0700
Re: sizeof(arr[0]) Richard Heathfield <rjh@cpax.org.uk> - 2015-06-16 19:14 +0100
Re: sizeof(arr[0]) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-06-16 11:43 -0700
Re: sizeof(arr[0]) Richard Heathfield <rjh@cpax.org.uk> - 2015-06-16 20:03 +0100
Re: sizeof(arr[0]) Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-06-16 19:15 +0100
Re: sizeof(arr[0]) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-06-16 11:34 -0700
Re: sizeof(arr[0]) Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-06-16 20:28 +0100
Re: sizeof(arr[0]) James Kuyper <jameskuyper@verizon.net> - 2015-06-16 15:42 -0400
Re: sizeof(arr[0]) Keith Thompson <kst-u@mib.org> - 2015-06-16 13:35 -0700
Re: sizeof(arr[0]) James Kuyper <jameskuyper@verizon.net> - 2015-06-16 16:59 -0400
Re: sizeof(arr[0]) Dr Nick <nospam-4@temporary-address.org.uk> - 2015-06-16 22:05 +0100
Re: sizeof(arr[0]) Keith Thompson <kst-u@mib.org> - 2015-06-16 14:27 -0700
Re: sizeof(arr[0]) Dr Nick <nospam-4@temporary-address.org.uk> - 2015-06-17 07:07 +0100
Re: sizeof(arr[0]) Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-06-17 01:22 +0100
Re: sizeof(arr[0]) glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-06-16 19:45 +0000
Re: sizeof(arr[0]) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-06-16 13:03 -0700
Re: sizeof(arr[0]) Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-06-17 10:58 +0100
Re: sizeof(arr[0]) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-06-17 05:58 -0700
Re: sizeof(arr[0]) Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-06-17 15:46 +0100
Re: sizeof(arr[0]) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-06-17 08:14 -0700
Re: sizeof(arr[0]) Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-06-17 17:58 +0100
Re: sizeof(arr[0]) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-06-17 10:07 -0700
Re: sizeof(arr[0]) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-06-17 10:09 -0700
Re: sizeof(arr[0]) David Kleinecke <dkleinecke@gmail.com> - 2015-06-17 10:46 -0700
Re: sizeof(arr[0]) Keith Thompson <kst-u@mib.org> - 2015-06-17 11:13 -0700
Re: sizeof(arr[0]) Nathan Wagner <nw@hydaspes.if.org> - 2015-06-18 07:14 +0000
Re: sizeof(arr[0]) David Brown <david.brown@hesbynett.no> - 2015-06-18 09:54 +0200
Re: sizeof(arr[0]) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-06-18 05:19 -0700
Re: sizeof(arr[0]) Keith Thompson <kst-u@mib.org> - 2015-06-17 10:53 -0700
Re: sizeof(arr[0]) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-06-17 11:17 -0700
Re: sizeof(arr[0]) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-06-17 13:59 -0700
Re: sizeof(arr[0]) Ian Collins <ian-news@hotmail.com> - 2015-06-18 13:41 +1200
Re: sizeof(arr[0]) David Brown <david.brown@hesbynett.no> - 2015-06-18 10:04 +0200
Re: sizeof(arr[0]) Keith Thompson <kst-u@mib.org> - 2015-06-16 13:18 -0700
Re: sizeof(arr[0]) Richard Heathfield <rjh@cpax.org.uk> - 2015-06-16 21:30 +0100
Re: sizeof(arr[0]) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-06-16 13:53 -0700
Re: sizeof(arr[0]) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-06-16 13:43 -0700
Re: sizeof(arr[0]) Richard Heathfield <rjh@cpax.org.uk> - 2015-06-16 21:52 +0100
Re: sizeof(arr[0]) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-06-16 14:01 -0700
Re: sizeof(arr[0]) David Brown <david.brown@hesbynett.no> - 2015-06-16 23:49 +0200
Re: sizeof(arr[0]) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-06-16 14:58 -0700
Re: sizeof(arr[0]) David Brown <david.brown@hesbynett.no> - 2015-06-17 14:10 +0200
Re: sizeof(arr[0]) Richard Heathfield <rjh@cpax.org.uk> - 2015-06-17 13:20 +0100
Re: sizeof(arr[0]) Keith Thompson <kst-u@mib.org> - 2015-06-16 14:16 -0700
Re: sizeof(arr[0]) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-06-16 14:39 -0700
Re: sizeof(arr[0]) gazelle@shell.xmission.com (Kenny McCormack) - 2015-06-16 18:38 +0000
Re: sizeof(arr[0]) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-06-16 11:45 -0700
Re: sizeof(arr[0]) Keith Thompson <kst-u@mib.org> - 2015-06-16 13:22 -0700
Re: sizeof(arr[0]) gazelle@shell.xmission.com (Kenny McCormack) - 2015-06-16 21:25 +0000
Re: sizeof(arr[0]) Keith Thompson <kst-u@mib.org> - 2015-06-16 11:05 -0700
Re: sizeof(arr[0]) James Kuyper <jameskuyper@verizon.net> - 2015-06-16 14:15 -0400
Re: sizeof(arr[0]) David Kleinecke <dkleinecke@gmail.com> - 2015-06-17 10:07 -0700
Re: sizeof(arr[0]) Keith Thompson <kst-u@mib.org> - 2015-06-17 11:16 -0700
Re: sizeof(arr[0]) David Kleinecke <dkleinecke@gmail.com> - 2015-06-18 10:22 -0700
Re: sizeof(arr[0]) Keith Thompson <kst-u@mib.org> - 2015-06-18 10:42 -0700
Re: sizeof(arr[0]) David Kleinecke <dkleinecke@gmail.com> - 2015-06-18 11:41 -0700
Re: sizeof(arr[0]) Philip Lantz <prl@canterey.us> - 2015-06-16 00:12 -0700
Re: sizeof(arr[0]) Richard Heathfield <rjh@cpax.org.uk> - 2015-06-16 10:12 +0100
Re: sizeof(arr[0]) Philip Lantz <prl@canterey.us> - 2015-06-16 09:12 -0700
Re: sizeof(arr[0]) Richard Heathfield <rjh@cpax.org.uk> - 2015-06-16 17:32 +0100
Re: sizeof(arr[0]) kuznecov.alexey@gmail.com - 2015-06-10 14:56 -0700
Re: sizeof(arr[0]) Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-06-10 23:53 +0100
Re: sizeof(arr[0]) Bartc <bc@freeuk.com> - 2015-06-11 00:33 +0100
Re: sizeof(arr[0]) Richard Heathfield <rjh@cpax.org.uk> - 2015-06-11 00:37 +0100
Re: sizeof(arr[0]) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-06-17 06:05 -0700
[OT] The number 42 (was Re: sizeof(arr[0])) David Brown <david.brown@hesbynett.no> - 2015-06-17 16:07 +0200
Re: [OT] The number 42 (was Re: sizeof(arr[0])) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-06-17 08:23 -0700
Re: [OT] The number 42 (was Re: sizeof(arr[0])) David Brown <david.brown@hesbynett.no> - 2015-06-18 10:21 +0200
Re: [OT] The number 42 (was Re: sizeof(arr[0])) David Kleinecke <dkleinecke@gmail.com> - 2015-06-17 10:35 -0700
Re: [OT] The number 42 (was Re: sizeof(arr[0])) David Brown <david.brown@hesbynett.no> - 2015-06-18 10:18 +0200
Re: [OT] The number 42 (was Re: sizeof(arr[0])) Richard Heathfield <rjh@cpax.org.uk> - 2015-06-18 10:08 +0100
Re: sizeof(arr[0]) Richard Heathfield <rjh@cpax.org.uk> - 2015-06-17 15:13 +0100
Re: sizeof(arr[0]) raltbos@xs4all.nl (Richard Bos) - 2015-06-18 20:38 +0000
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