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Groups > comp.lang.c > #147572
| From | David Brown <david.brown@hesbynett.no> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: memcpy not memcpying? |
| Date | 2019-11-04 13:10 +0100 |
| Organization | A noiseless patient Spider |
| Message-ID | <qpp4ga$eq6$1@dont-email.me> (permalink) |
| References | (17 earlier) <%%DvF.115593$Yl3.480@fx24.am4> <qpnj12$17q$1@dont-email.me> <BoJvF.123253$m0L.2016@fx15.am4> <qposrb$2sq$1@dont-email.me> <87eeynlwc7.fsf@bsb.me.uk> |
On 04/11/2019 12:22, Ben Bacarisse wrote:
> David Brown <david.brown@hesbynett.no> writes:
> <cut>
>> You plan your program. Is it realistic to think that the type of
>> "nsymbols" would change - that 2 G symbols will not be enough? If that
>> is the case, you write:
>>
>> typedef int symbolcount_t;
>> symbolcount_t nsymbols;
>> #define PRIsymbolcount d
>
> #define PRIsymbolcount "d"
Indeed.
>
>> void debug_print_symbolcounts(symbolcount__t i) {
>> printf("Symbol %" PRIsymbolcount " out of %" PRIsymbolcount,
>> i, nsymbols);
>> }
>>
>> Or maybe, if you don't like printf format macros (and lets be honest, no
>> one does - even if it is the least bad solution, it is still ugly), you
>> write:
>>
>> typedef int symbolcount_t;
>> symbolcount_t nsymbols;
>>
>> void print_symbolcounts(symbolcount_t i) {
>> _Static_assert(sizeof(symbolcount_t) == sizeof(int),
>> "Fix this function if symbolcount_t changes");
>> printf("%d", i);
>> }
>
> I think I might use _Generic here because checking the size is not
> always going to be enough:
>
> _Static_assert(
> _Generic(i, int: 1, default: 0),
> "Check this because symbolcount_t is not compatible with int."
> );
I mentioned _Generic later on as a way to aid printing, but I hadn't
thought of using them in a static assert like this. Thank you for the idea!
>
> This works (in both clang and gcc) with -std=c11 -pedantic, but I am not
> sure that _Generic /must/ be allowed here. It would be a shame if
> generic selections were not considered to be standard constant
> expressions. Have I missed something in the standard?
>
> <cut>
> Bart writes:
>>> I think they would. Ben said in another post that Haskell has C-like
>>> formats, but also "v" that works for any variable. That is the
>>> equivalent of my "?" (which I can change to "v" if that has no existing
>>> meaning).
>>
>> Haskell is not C. There are vast amounts of cool features in Haskell
>> that C does not have - and equally, vast amounts of things that are
>> simple to do in C, but much harder to handle in a language like
>> Haskell.
>
> Of course. Mind you, a better example would have been Go (since it's
> designed in part by DMR), though Go does not check the format at compile
> time but at run time. It also uses %v.
>
>>> But I can't imagine when someone writing Haskell would want to bother
>>> with anything other than "v".
>
> There are many reasons to use other formats, but an obvious one is to
> restrict printing to the type given in the format. This will act a bit like
> the _Static_assert above.
>
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memcpy not memcpying? DFS <nospam@dfs.com> - 2019-11-01 08:42 -0400
Re: memcpy not memcpying? DFS <nospam@dfs.com> - 2019-11-01 08:49 -0400
Re: memcpy not memcpying? James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-11-01 09:24 -0400
Re: memcpy not memcpying? DFS <nospam@dfs.com> - 2019-11-01 09:46 -0400
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Re: memcpy not memcpying? Keith Thompson <kst-u@mib.org> - 2019-11-01 10:19 -0700
Re: memcpy not memcpying? David Brown <david.brown@hesbynett.no> - 2019-11-01 21:14 +0100
Re: memcpy not memcpying? DFS <nospam@dfs.com> - 2019-11-01 17:16 -0400
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-01 22:42 +0000
Re: memcpy not memcpying? Richard Damon <Richard@Damon-Family.org> - 2019-11-01 21:10 -0400
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Re: memcpy not memcpying? Keith Thompson <kst-u@mib.org> - 2019-11-02 02:15 -0700
Re: memcpy not memcpying? David Brown <david.brown@hesbynett.no> - 2019-11-02 13:04 +0100
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-02 13:43 +0000
Re: memcpy not memcpying? David Brown <david.brown@hesbynett.no> - 2019-11-02 17:24 +0100
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-02 17:00 +0000
Re: memcpy not memcpying? Keith Thompson <kst-u@mib.org> - 2019-11-02 13:06 -0700
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-02 21:05 +0000
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-02 22:40 +0000
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Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-02 23:47 +0000
Re: memcpy not memcpying? Keith Thompson <kst-u@mib.org> - 2019-11-02 18:22 -0700
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-03 13:27 +0000
Re: memcpy not memcpying? David Brown <david.brown@hesbynett.no> - 2019-11-03 17:46 +0100
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-03 17:20 +0000
Re: memcpy not memcpying? Manfred <noname@add.invalid> - 2019-11-03 19:44 +0100
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-03 19:36 +0000
Re: memcpy not memcpying? Manfred <noname@add.invalid> - 2019-11-03 22:57 +0100
Re: memcpy not memcpying? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-11-03 22:39 +0000
Re: memcpy not memcpying? David Brown <david.brown@hesbynett.no> - 2019-11-03 23:06 +0100
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-03 23:28 +0000
Re: memcpy not memcpying? David Brown <david.brown@hesbynett.no> - 2019-11-04 11:00 +0100
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-04 11:14 +0000
Re: memcpy not memcpying? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-11-04 11:22 +0000
Re: memcpy not memcpying? David Brown <david.brown@hesbynett.no> - 2019-11-04 13:10 +0100
Re: memcpy not memcpying? Keith Thompson <kst-u@mib.org> - 2019-11-04 10:03 -0800
Re: memcpy not memcpying? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-11-04 19:36 +0000
Re: memcpy not memcpying? Keith Thompson <kst-u@mib.org> - 2019-11-05 10:04 -0800
Re: memcpy not memcpying? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-11-04 20:58 -0800
Re: memcpy not memcpying? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-11-04 22:01 -0800
Re: memcpy not memcpying? Autist <autist69@gmail.com> - 2019-11-04 12:56 +0100
Re: memcpy not memcpying? James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-11-04 09:50 -0500
Re: memcpy not memcpying? scott@slp53.sl.home (Scott Lurndal) - 2019-11-04 20:26 +0000
Re: memcpy not memcpying? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2019-11-04 04:34 -0800
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-04 13:05 +0000
Re: memcpy not memcpying? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-11-04 14:09 +0000
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-04 15:11 +0000
Re: memcpy not memcpying? Melzzzzz <Melzzzzz@zzzzz.com> - 2019-11-04 15:15 +0000
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Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-03 20:20 +0000
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Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-03 12:52 +0000
Re: memcpy not memcpying? Öö Tiib <ootiib@hot.ee> - 2019-11-03 23:34 -0800
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-04 09:36 +0000
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-04 16:20 +0000
Re: memcpy not memcpying? Ian Collins <ian-news@hotmail.com> - 2019-11-04 07:46 +1300
Re: memcpy not memcpying? Keith Thompson <kst-u@mib.org> - 2019-11-03 12:26 -0800
Re: memcpy not memcpying? David Brown <david.brown@hesbynett.no> - 2019-11-03 17:31 +0100
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-03 17:05 +0000
Re: memcpy not memcpying? already5chosen@yahoo.com - 2019-11-03 09:14 -0800
Re: memcpy not memcpying? Keith Thompson <kst-u@mib.org> - 2019-11-03 12:32 -0800
Re: memcpy not memcpying? already5chosen@yahoo.com - 2019-11-03 14:59 -0800
Re: memcpy not memcpying? already5chosen@yahoo.com - 2019-11-03 15:19 -0800
Re: memcpy not memcpying? already5chosen@yahoo.com - 2019-11-03 17:00 -0800
Re: memcpy not memcpying? DFS <nospam@dfs.com> - 2019-11-02 11:16 -0400
Re: memcpy not memcpying? David Brown <david.brown@hesbynett.no> - 2019-11-02 17:26 +0100
Re: memcpy not memcpying? Barry Schwarz <schwarzb@delq.com> - 2019-11-01 06:39 -0700
Re: memcpy not memcpying? DFS <nospam@dfs.com> - 2019-11-01 09:56 -0400
Re: memcpy not memcpying? Barry Schwarz <schwarzb@delq.com> - 2019-11-01 12:39 -0700
Re: memcpy not memcpying? guinness.tony@gmail.com - 2019-11-01 06:49 -0700
Re: memcpy not memcpying? jak <nospam@please.ty> - 2019-11-01 20:40 +0100
Re: memcpy not memcpying? Autist <autist69@gmail.com> - 2019-11-01 14:26 +0100
Re: memcpy not memcpying? Keith Thompson <kst-u@mib.org> - 2019-11-01 10:22 -0700
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-01 19:44 +0000
Re: memcpy not memcpying? Autist <autist69@gmail.com> - 2019-11-01 21:31 +0100
Re: memcpy not memcpying? James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-11-01 09:39 -0400
Re: memcpy not memcpying? Autist <autist69@gmail.com> - 2019-11-01 14:42 +0100
Re: memcpy not memcpying? James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-11-01 09:48 -0400
Re: memcpy not memcpying? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2019-11-01 06:47 -0700
Re: memcpy not memcpying? Autist <autist69@gmail.com> - 2019-11-01 14:58 +0100
Re: memcpy not memcpying? DFS <nospam@dfs.com> - 2019-11-01 10:22 -0400
Re: memcpy not memcpying? Autist <autist69@gmail.com> - 2019-11-01 18:38 +0100
Re: memcpy not memcpying? scott@slp53.sl.home (Scott Lurndal) - 2019-11-01 17:54 +0000
Re: memcpy not memcpying? Autist <autist69@gmail.com> - 2019-11-01 20:24 +0100
Re: memcpy not memcpying? DFS <nospam@dfs.com> - 2019-11-01 15:24 -0400
Re: memcpy not memcpying? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-11-01 23:19 +0000
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