Re: memcpy not memcpying?

Subject	Re: memcpy not memcpying?
Newsgroups	comp.lang.c
References	(10 earlier) <ln7e4i6o0y.fsf@kst-u.example.com> <OcmvF.87562$Pt2.3193@fx23.am4> <ln36f57ul5.fsf@kst-u.example.com> <EAovF.246198$IsL.142854@fx08.am4> <lnv9s169ev.fsf@kst-u.example.com>
From	Bart <bc@freeuk.com>
Message-ID	<1BAvF.13970$mB7.12243@fx32.am4> (permalink)
Organization	virginmedia.com
Date	2019-11-03 13:27 +0000

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On 03/11/2019 01:22, Keith Thompson wrote:
> Bart <bc@freeuk.com> writes:

>> MS libraries support I64 and I32 width specifiers (as in "%I64d"). That
>> wouldn't have been a bad starting point.
> 
> Maybe -- but the MS libraries can assume that the implementation
> supports integer types of exactly 32 and 64 bits.  The C standard
> does not make that assumption.  For example, <inttypes.h>

inttypes.h/stdint.h defines int32_t, int64_t etc for which I32, I64 etc 
would have been far better solutions to the print problem than those 
ugly PRI32d macros.

Of course, it would require additional support within printf 
implementations, but so did %zu.

> defines macros PRId32, PRIdLEAST32, and PRIdFAST32 for int32_t,
> int_least32_t, and int_fast32_t, respectively.  The type int32_t is
> optional; int_least32_t and int_fast32_t are mandatory.  The standard
> has to cover more possible target systems than Windows does (or
> Linux, or POSIX), including systems that may not exist yet.

Then it would have been reasonable to mandate I64 support only for 
systems where int64_t exists.

> You can see a list of the macros in N1570 7.8.1.  Some of them
> exist for each width, at least 8, 16, 32, and 64, for a total
> of 84 PRI* macros and 70 SCN* macros if I've counted correctly.
> (Exotic implementations might support other widths, or might
> not support all of 8, 16, 32, and 64 for the exact-width types.)
> You *could* implement those 154 possibilities directly in the *printf
> and *scanf functions, with distinct syntaxes in the format strings,
> but I prefer the way it's done in the standard.
> 
> I'm not saying that the PRI* and SCN* macros are ideal, but I
> can't think of a cleaner way to define them while supporting the
> same functionality.  No doubt your private language does it better,
> but that doesn't help C.

I suggested a format "%?" where the compiler fills in the default type 
where the format string is visible. Which is nearly always.

But because it's not perfect, conventional format codes would still be 
needed.

(My implementation of %? was just a proof-of-concept and is not 
complete, but it's an enhancement I've kept as it is genuinely handy, 
even if limited to one compiler.

(I haven't done field widths, or allowed for X or c interpretations of 
an int, or forcing signed to unsigned and vice versa, or selecting 
different kinds of float formats etc etc. But these can be accommodated.

The important thing is to have a format where you don't need to know the 
exact type of the thing being printed, just whether it's int, float, 
string or pointer. Or, very often, not even that - just print X, 
whatever type it happens to be, or print X with a given width.))

Thread

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
        Re: memcpy not memcpying? James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-11-01 09:49 -0400
        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
                Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-02 11:36 +0000
            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
                Re: memcpy not memcpying? Keith Thompson <kst-u@mib.org> - 2019-11-02 15:59 -0700
                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
                Re: memcpy not memcpying? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-11-04 15:43 +0000
                Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-03 20:20 +0000
                Re: memcpy not memcpying? Ian Collins <ian-news@hotmail.com> - 2019-11-03 14:37 +1300
                Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-03 11:01 +0000
                Re: memcpy not memcpying? Öö Tiib <ootiib@hot.ee> - 2019-11-03 04:03 -0800
                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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