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| From | Keith Thompson <kst-u@mib.org> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: A very simple parser with scanf & C |
| Date | 2011-09-26 12:18 -0700 |
| Organization | None to speak of |
| Message-ID | <lny5xb15ao.fsf@nuthaus.mib.org> (permalink) |
| References | (13 earlier) <j5nstl$mg4$1@dont-email.me> <ln7h4w30c6.fsf@nuthaus.mib.org> <j5o09d$eul$1@dont-email.me> <j5o0vd$jqr$1@dont-email.me> <j5piu0$ugu$1@dont-email.me> |
"BartC" <bc@freeuk.com> writes:
> "James Kuyper" <jameskuyper@verizon.net> wrote in message
> news:j5o0vd$jqr$1@dont-email.me...
>> On 09/25/2011 03:43 PM, BartC wrote:
>
>>> Are you saying that while an implementation's char type can be signed or
>>> unsigned, it's isalpha() function assumes unsigned?
>
>> Keep in mind that the standard specifies that fgetc() "obtains that
>> character as an unsigned char converted to an int", unless it returns
>> EOF to indicate an error. Those specifications make fgetc() and the
>> character classification macros good matches for each other.
>
> OK, so everywhere you look, it's clear that having unsigned char types is a
> good idea.
>
> So, even if signed chars are not eliminated completely, why are they so
> popular, given that it is (presumably) the implementation's free choice to
> choose between signed and unsigned? (At least, the three compilers I have,
> all have char as signed.)
>
> Then signed chars would only ever be used by someone needing a small signed
> integer.
Expressions of type char are promoted to int in most contexts. If plain
char is signed, this promotion can be done with a sign extension, which
is typically quite cheap. If plain char is unsigned, it might be more
expensive. (I don't have more specific information, but it's what I was
told when I asked a similar question some time ago.)
I agree that making plain char unsigned would be conceptually simpler.
--
Keith Thompson (The_Other_Keith) kst-u@mib.org <http://www.ghoti.net/~kst>
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"
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A very simple parser with scanf & C pozz <pozzugno@gmail.com> - 2011-09-23 07:03 -0700
Re: A very simple parser with scanf & C Nobody <nobody@nowhere.com> - 2011-09-23 18:28 +0100
Re: A very simple parser with scanf & C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-09-23 18:29 +0100
Re: A very simple parser with scanf & C pozz <pozzugno@gmail.com> - 2011-09-23 23:16 +0200
Re: A very simple parser with scanf & C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-09-24 00:09 +0100
Re: A very simple parser with scanf & C pozz <pozzugno@gmail.com> - 2011-09-24 09:32 +0200
Re: A very simple parser with scanf & C "BartC" <bc@freeuk.com> - 2011-09-23 21:24 +0100
Re: A very simple parser with scanf & C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-09-23 22:00 +0100
Re: A very simple parser with scanf & C "BartC" <bc@freeuk.com> - 2011-09-24 00:04 +0100
Re: A very simple parser with scanf & C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-09-24 00:34 +0100
Re: A very simple parser with scanf & C "BartC" <bc@freeuk.com> - 2011-09-24 01:00 +0100
Re: A very simple parser with scanf & C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-09-24 02:42 +0100
Re: A very simple parser with scanf & C "BartC" <bc@freeuk.com> - 2011-09-24 12:13 +0100
Re: A very simple parser with scanf & C "BartC" <bc@freeuk.com> - 2011-09-24 12:25 +0100
Re: A very simple parser with scanf & C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-09-24 15:05 +0100
Re: A very simple parser with scanf & C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-09-24 14:45 +0100
Re: A very simple parser with scanf & C "BartC" <bc@freeuk.com> - 2011-09-24 17:45 +0100
Re: A very simple parser with scanf & C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-09-24 22:21 +0100
Re: A very simple parser with scanf & C "BartC" <bc@freeuk.com> - 2011-09-25 00:52 +0100
Re: A very simple parser with scanf & C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-09-25 01:54 +0100
Re: A very simple parser with scanf & C "BartC" <bc@freeuk.com> - 2011-09-25 02:51 +0100
Re: A very simple parser with scanf & C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-09-25 12:22 +0100
Re: A very simple parser with scanf & C Gene <gene.ressler@gmail.com> - 2011-09-25 01:35 -0700
Re: A very simple parser with scanf & C pete <pfiland@mindspring.com> - 2011-09-25 08:41 -0400
Re: A very simple parser with scanf & C Gene <gene.ressler@gmail.com> - 2011-09-25 11:23 -0700
Re: A very simple parser with scanf & C Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-09-25 19:41 +0300
Re: A very simple parser with scanf & C "BartC" <bc@freeuk.com> - 2011-09-25 19:45 +0100
Re: A very simple parser with scanf & C Keith Thompson <kst-u@mib.org> - 2011-09-25 12:10 -0700
Re: A very simple parser with scanf & C "BartC" <bc@freeuk.com> - 2011-09-25 20:43 +0100
Re: A very simple parser with scanf & C James Kuyper <jameskuyper@verizon.net> - 2011-09-25 15:55 -0400
Re: A very simple parser with scanf & C "BartC" <bc@freeuk.com> - 2011-09-26 11:07 +0100
Re: A very simple parser with scanf & C Richard Damon <news.x.richarddamon@xoxy.net> - 2011-09-26 11:40 -0400
Re: A very simple parser with scanf & C Keith Thompson <kst-u@mib.org> - 2011-09-26 12:22 -0700
Re: A very simple parser with scanf & C pacman@kosh.dhis.org (Alan Curry) - 2011-09-26 21:19 +0000
Re: A very simple parser with scanf & C Keith Thompson <kst-u@mib.org> - 2011-09-26 16:11 -0700
Re: A very simple parser with scanf & C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-09-26 23:26 +0100
Re: A very simple parser with scanf & C Keith Thompson <kst-u@mib.org> - 2011-09-26 12:18 -0700
Re: A very simple parser with scanf & C Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-09-27 02:27 +0300
Re: A very simple parser with scanf & C Keith Thompson <kst-u@mib.org> - 2011-09-27 10:06 -0700
Re: A very simple parser with scanf & C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-09-27 21:10 +0100
Re: A very simple parser with scanf & C Seebs <usenet-nospam@seebs.net> - 2011-09-26 22:59 +0000
Re: A very simple parser with scanf & C Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-09-30 05:18 -0700
Re: A very simple parser with scanf & C "BartC" <bc@freeuk.com> - 2011-09-30 17:06 +0100
Re: A very simple parser with scanf & C Richard Damon <news.x.richarddamon@xoxy.net> - 2011-09-25 18:05 -0400
Re: A very simple parser with scanf & C Keith Thompson <kst-u@mib.org> - 2011-09-25 15:30 -0700
Re: A very simple parser with scanf & C Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 14:01 -0800
Re: A very simple parser with scanf & C pete <pfiland@mindspring.com> - 2012-01-25 11:05 -0500
Re: A very simple parser with scanf & C Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-31 16:01 -0800
Re: A very simple parser with scanf & C pete <pfiland@mindspring.com> - 2012-01-31 23:47 -0500
Re: A very simple parser with scanf & C Tim Rentsch <txr@alumni.caltech.edu> - 2012-03-08 09:21 -0800
Re: A very simple parser with scanf & C pete <pfiland@mindspring.com> - 2012-03-10 15:18 -0500
Re: A very simple parser with scanf & C Tim Rentsch <txr@alumni.caltech.edu> - 2012-03-13 15:49 -0700
Re: A very simple parser with scanf & C pete <pfiland@mindspring.com> - 2012-03-14 18:56 -0500
Re: A very simple parser with scanf & C Tim Rentsch <txr@alumni.caltech.edu> - 2012-03-15 17:37 -0700
Re: A very simple parser with scanf & C pete <pfiland@mindspring.com> - 2012-03-17 00:24 -0500
Re: A very simple parser with scanf & C Tim Rentsch <txr@alumni.caltech.edu> - 2012-03-21 05:21 -0700
Re: A very simple parser with scanf & C pozz <pozzugno@gmail.com> - 2011-09-23 23:23 +0200
Re: A very simple parser with scanf & C "BartC" <bc@freeuk.com> - 2011-09-23 23:53 +0100
Re: A very simple parser with scanf & C Rui Maciel <rui.maciel@gmail.com> - 2011-09-25 14:07 +0100
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