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| From | Uncle Steve <stevet810@gmail.com> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Types in C |
| Date | 2011-05-24 10:58 -0400 |
| Organization | Friends of the Galactic Collective |
| Message-ID | <46bfca6e0cc73cf-bd09a@gmail.com> (permalink) |
| References | (5 earlier) <ires4n$et7$1@dont-email.me> <a1c7e744c9f0301-49174@gmail.com> <irf45o$nnp$1@dont-email.me> <c6df7e1de1fd10f-d35e5@gmail.com> <irfd7c$1en$1@dont-email.me> |
On Tue, May 24, 2011 at 12:46:29AM -0500, Shao Miller wrote:
> On 5/23/2011 11:03 PM, Uncle Steve wrote:
> >On Mon, May 23, 2011 at 10:12:02PM -0500, Shao Miller wrote:
> >>The standard definition in C99, if I'm not mistaken, includes:
> >>
> >> "The meaning of a value stored in an object or returned by a function
> >>is determined by the /type/ of the expression used to access it..."
> >
> >Doesn't that specify when and how a cast occurs in expression
> >evaluation?
>
> No. That quotation is from here[n1256.pdf:6.2.5p1]. The slashes I
> injected into the quoted text were intended to denote italics in the
> original. For italics in the original, we have that "... Other terms
> are defined where they appear in /italic/ type or on the left side of a
> syntax rule. ..."[n1256.pdf:3p1] *
The full paragraph (from a draft version) is more compelling:
6.2.5 Types
#1
The meaning of a value stored in an object or returned by a
function is determined by the type of the expression used to access
it. (An identifier declared to be an object is the simplest such
expression; the type is specified in the declaration of the
identifier.) Types are partitioned into object types (types that
describe objects), function types (types that describe functions),
and incomplete types (types that describe objects but lack
information needed to determine their sizes).
> As far as I know, a cast occurs when one uses something like:
>
> (type)expression
>
> in code. Perhaps you were thinking of "conversion" rather than "cast"?
>
> >int function(void) {
> > return(42);
> >}
> >
>
> Just out of curiosity, do you ever override the 'return' keyword with a
> function-like macro? That's one possible reason for wrapping return
> values with parentheses and it'd be interesting to get a sense of how
> many people have that habit for that intention.
It's a cognitive semantic quirk. Return kind-of looks like it is a
special function that transfers control to the original caller, and so
I put return values in parenthesis because that's what you do with
real functions. I know it's not a function, but try to tell that to
my brain.
> >...
> >
> >long v = function();
> >
> >So what I gather from the quoted text is that the return value of
> >function() is promoted to long before the assignment occurs. Is that
> >correct?
> >
>
> Actually, I don't think so. I think that "...the value of the right
> operand is converted to the type of the assignment expression and
> replaces the value stored in the object designated by the left
> operand."[n1256.pdf:6.5.16.1p2]
>
> But anyway, in regards to "user defined types," because that doesn't
> appear in a standard of C (or does it?), I think it's possible that it's
> a subject where discussion can be challenging by having different
> understandings of the term for different people.
Indeed, and as real technical specifications typically use language
with more precision than colloquial written English, there is plenty
of room for misunderstanding between those who have differing degrees
of understanding.
> I _think_ that what you have offered is congruent with "you, the
> programmer, don't get to invent/specify a type which is not a derived type."
>
> I _think_ what at least one other poster has offered is congruent with
> "if you, the programmer, specify a derived type, then that type could be
> called a youser^H^H^H^H^H^Huser-defined type, since _something_ defined it."
>
> Or maybe not.
I was mostly taking issue with the idea that a derived type is
qualitatively equivalent to a /de-novo/ basic type, which was the
implication given in the way some were using the term 'type' in their
statements -- by my reckoning of their meaning. When the word 'type'
is used with precision similar to a word like 'run' ("the computer
runs"), it is difficult to be entirely sure what is really meant.
> * I hope to some day purchase some actual standards. The efforts that
> have gone into them can certainly save me some time == money while
> attempting to write portable C. :)
Actual printed copies are fairly expensive from what I gather.
Available from Global Engineering Documents, as per the C-FAQ, section
5.2.
Regards,
Uncle Steve
--
Should a professional politician be charged with molestation if he
kisses babies while attending political rallies?
Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
Types in C jacob navia <jacob@spamsink.net> - 2011-05-22 21:29 +0200
Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-22 12:48 -0700
Re: Types in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-05-22 23:03 +0100
Re: Types in C jacob navia <jacob@spamsink.net> - 2011-05-23 10:35 +0200
Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-23 08:40 -0700
Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-23 17:19 +0000
Re: Types in C John Gordon <gordon@panix.com> - 2011-05-23 17:54 +0000
Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-23 11:33 -0700
Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-23 11:44 -0700
Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-23 19:08 +0000
Re: Types in C jacob navia <jacob@spamsink.net> - 2011-05-23 20:50 +0200
Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-23 12:11 -0700
Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-23 19:45 +0000
Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-23 13:03 -0700
Re: Types in C jacob navia <jacob@spamsink.net> - 2011-05-23 22:25 +0200
Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-23 14:38 -0700
Re: Types in C jacob navia <jacob@spamsink.net> - 2011-05-23 23:45 +0200
Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-23 22:02 +0000
Re: Types in C jacob navia <jacob@spamsink.net> - 2011-05-24 00:10 +0200
Re: Types in C jacob navia <jacob@spamsink.net> - 2011-05-23 22:12 +0200
Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-23 13:27 -0700
Re: Types in C jacob navia <jacob@spamsink.net> - 2011-05-23 22:33 +0200
Re: Types in C Martin Ambuhl <mambuhl@earthlink.net> - 2011-05-24 03:17 -0400
Re: Types in C jacob navia <jacob@spamsink.net> - 2011-05-24 10:55 +0200
Re: Types in C Ian Collins <ian-news@hotmail.com> - 2011-05-24 09:29 +1200
Re: Types in C jacob navia <jacob@spamsink.net> - 2011-05-23 23:42 +0200
Re: Types in C Ian Collins <ian-news@hotmail.com> - 2011-05-24 09:51 +1200
Re: Types in C jacob navia <jacob@spamsink.net> - 2011-05-24 00:04 +0200
Re: Types in C Ian Collins <ian-news@hotmail.com> - 2011-05-24 10:57 +1200
Re: Types in C David Thompson <dave.thompson2@verizon.net> - 2011-06-01 16:33 -0400
Re: Types in C Shao Miller <sha0.miller@gmail.com> - 2011-05-23 19:33 -0500
Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-24 08:27 -0700
Re: Types in C Tim Rentsch <txr@alumni.caltech.edu> - 2011-05-31 00:40 -0700
Re: Types in C jacob navia <jacob@spamsink.net> - 2011-05-31 11:32 +0200
Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-31 11:30 -0700
Re: Types in C Tim Rentsch <txr@alumni.caltech.edu> - 2011-06-01 01:23 -0700
Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-23 16:51 -0400
Re: Types in C Ian Collins <ian-news@hotmail.com> - 2011-05-24 09:25 +1200
Re: Types in C jacob navia <jacob@spamsink.net> - 2011-05-23 23:40 +0200
Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-24 08:36 -0700
Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-23 17:53 -0400
Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-23 22:24 +0000
Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-23 19:23 -0400
Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-23 23:57 +0000
Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-23 21:22 -0400
Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-24 03:46 +0000
Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-24 00:24 -0400
Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-24 04:44 +0000
Re: Types in C pete <pfiland@mindspring.com> - 2011-05-24 07:46 -0400
Re: Types in C James Kuyper <jameskuyper@verizon.net> - 2011-05-24 07:48 -0400
Re: Types in C Ian Collins <ian-news@hotmail.com> - 2011-05-24 10:35 +1200
Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-23 22:38 +0000
Re: Types in C Ian Collins <ian-news@hotmail.com> - 2011-05-24 10:53 +1200
Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-23 23:17 +0000
Re: Types in C Ian Collins <ian-news@hotmail.com> - 2011-05-24 11:24 +1200
Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-23 23:39 +0000
Re: Types in C jacob navia <jacob@spamsink.net> - 2011-05-24 11:23 +0200
Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-24 08:46 -0700
Re: Types in C Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-05-24 09:14 -0700
Re: Types in C Michael Press <rubrum@pacbell.net> - 2011-05-28 21:50 -0700
Re: Types in C "io_x" <a@b.c.invalid> - 2011-06-07 19:50 +0200
Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-23 19:33 -0400
Re: Types in C Ian Collins <ian-news@hotmail.com> - 2011-05-24 12:03 +1200
Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-23 21:27 -0400
Re: Types in C Ian Collins <ian-news@hotmail.com> - 2011-05-24 13:47 +1200
Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-23 23:45 -0400
Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-24 00:07 -0700
Re: Types in C James Kuyper <jameskuyper@verizon.net> - 2011-05-24 08:05 -0400
Re: Types in C Shao Miller <sha0.miller@gmail.com> - 2011-05-23 19:54 -0500
Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-23 21:03 -0400
Re: Types in C Shao Miller <sha0.miller@gmail.com> - 2011-05-23 22:12 -0500
Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-24 00:03 -0400
Re: Types in C pete <pfiland@mindspring.com> - 2011-05-24 00:19 -0400
Re: Types in C pete <pfiland@mindspring.com> - 2011-05-24 00:20 -0400
Re: Types in C Shao Miller <sha0.miller@gmail.com> - 2011-05-24 00:46 -0500
Re: Types in C pete <pfiland@mindspring.com> - 2011-05-24 07:36 -0400
Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-24 10:58 -0400
Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-24 09:40 -0700
Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-24 21:36 -0400
Re: Types in C David Thompson <dave.thompson2@verizon.net> - 2011-06-01 16:33 -0400
Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-24 16:50 +0000
Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-24 21:10 -0400
Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-24 18:19 -0700
Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-24 21:42 -0400
Re: Types in C Shao Miller <sha0.miller@gmail.com> - 2011-05-24 23:47 -0500
Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-25 10:13 -0400
Re: Types in C Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-05-24 22:19 -0600
Re: Types in C Dr Nick <3-nospam@temporary-address.org.uk> - 2011-05-25 07:04 +0100
Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-25 08:53 -0700
Re: Types in C Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-05-25 10:11 -0600
Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-24 09:02 -0700
Re: Types in C James Kuyper <jameskuyper@verizon.net> - 2011-05-24 07:37 -0400
Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-23 22:02 +0000
Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-23 18:15 -0400
Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-23 22:25 +0000
Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-23 19:39 -0400
Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-23 23:57 +0000
Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-23 21:10 -0400
Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-24 01:58 +0000
Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-23 23:56 -0400
Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-24 04:32 +0000
Re: Types in C "BartC" <bc@freeuk.com> - 2011-05-25 01:29 +0100
Re: Types in C Shao Miller <sha0.miller@gmail.com> - 2011-05-23 22:20 -0500
Re: Types in C Shao Miller <sha0.miller@gmail.com> - 2011-05-23 22:42 -0500
Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-24 00:07 -0400
Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-24 04:44 +0000
Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-24 10:24 -0400
Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-24 16:50 +0000
Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-24 21:16 -0400
Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-25 03:36 +0000
Re: Types in C Shao Miller <sha0.miller@gmail.com> - 2011-05-24 01:26 -0500
Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-24 11:04 -0400
Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-24 09:06 -0700
Re: Types in C David Thompson <dave.thompson2@verizon.net> - 2011-06-01 16:33 -0400
Re: Types in C Marcin Grzegorczyk <mgrzegor@poczta.onet.pl> - 2011-05-30 22:42 +0200
Re: Types in C Shao Miller <sha0.miller@gmail.com> - 2011-05-30 17:45 -0500
Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-31 08:47 -0700
Re: Types in C Shao Miller <sha0.miller@gmail.com> - 2011-05-31 13:54 -0400
Re: Types in C jacob navia <jacob@spamsink.net> - 2011-05-31 00:16 +0200
Re: Types in C Shao Miller <sha0.miller@gmail.com> - 2011-05-30 18:30 -0500
Re: Types in C Marcin Grzegorczyk <mgrzegor@poczta.onet.pl> - 2011-06-02 22:44 +0200
Re: Types in C jacob navia <jacob@spamsink.net> - 2011-06-02 22:49 +0200
Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-06-02 15:26 -0700
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