Re: Beginner....Decimal/Octal converter help

From	Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups	comp.lang.c
Subject	Re: Beginner....Decimal/Octal converter help
Date	2022-12-26 06:09 -0800
Organization	A noiseless patient Spider
Message-ID	<86tu1iw91p.fsf@linuxsc.com> (permalink)
References	(11 earlier) <87r10hzn19.fsf@bsb.me.uk> <86v8ptpa7u.fsf@linuxsc.com> <cLxTK.200646$PRW4.166956@fx11.iad> <867d26ntiv.fsf@linuxsc.com> <uwjUK.126149$IRd5.25738@fx10.iad>

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Richard Damon <Richard@Damon-Family.org> writes:

> On 9/14/22 6:24 AM, Tim Rentsch wrote:
>
>> Richard Damon <Richard@Damon-Family.org> writes:
>>
>>> On 9/11/22 11:01 PM, Tim Rentsch wrote:
>>>
>>>> Ben Bacarisse <ben.usenet@bsb.me.uk> writes:
>>>>
>>>>> [...] I worry that, except when matching externally defined
>>>>> structures, the use of the intN_t (and maybe even the uintN_t)
>>>>> types is almost always knee-jerk programming.
>>>>
>>>> Completely agree.
>>>
>>> I would just slightly disagree.
>>>
>>> Many programs are not designed to be "highly portable", and it may
>>> be a reasonable assumption that a given program will only be run
>>> on machines which is based on 8 bit bytes.
>>
>> I am taking 8-bit bytes as being the crucial property in the
>> remarks below.  There are obvious counterparts for other
>> properties, such as having a two's complement representation.
>>
>>> Since [u]intN_t is the shortest way to specify a size that will
>>> likely migrate over modereate architecture variations for variable
>>> where you do want to specify the "size" of the variable, using
>>> them makes sense.
>>
>> First off, I wouldn't say using int8_t or uint8_t is the shortest
>> way to ensure 8-bit bytes.  The way such types are typically
>> used, there will be lots of 'int8_t's or 'uint8_t's scattered
>> through the source code, with a correspondingly large footprint
>> in the program source.  It is shorter to write in just one header
>> file in the program
>>
>>      #include <limits.h>
>>      #if CHAR_BIT != 8
>>      # error oops.. this program relies on chars being 8 bits...
>>      #endif
>>
>>      typedef unsigned char U8;
>>      typedef   signed char S8;
>>
>> which also can be used in implementations that don't support
>> C99.
>
> Yes, but then you get the problem that stdint.h was made to solve,
> that of many variations of this naming possible existing in the
> program, and the risk of duplication of names.

That's your imagination talking, not the C standard.

> I suspect that one reason int8_t is slightly ugly is that it was a
> name the standard could fairly safely grab and not get into too
> many conflicts.
>
> Yes, a final application code could do something like that, and
> not have issues, but library code can't afford the name pollution.

The [u]intN_t types are not used elsewhere in the C library.  (I
believe that also holds true for the fast and least-width types.)
Some people might imagine that they are, but they are not.

>> Second, ignoring the question of which technique is shortest,
>> using [u]int8_t is often not a good way.  A problem with the
>> exact width types is that they are both an under-specification and
>> an over-specification:  over-specification because they often
>> include properties that aren't important (such as having no trap
>> representations), and under-specification because they might not
>> have properties that are otherwise desirable (such as being
>> exempt from anti-alias rules, as the character types are).
>> Granted, such problems are not likely to occur, but there is no
>> good reason to take the risk when it can be easily avoided.
>
> Readability of simple STANDARD names is important.  The looser
> specified types will have almost exactly properties.  Remember,
> the criteria was that the programmer KNEW that the machine was a
> standard 8-bit byte two's complement machine due to other
> dependencies in the code, thus KNOWS that the "over-specified"
> properties WILL hold.
>
> As far as exempt from the anti-alias rules, I don't think there
> has been a "standard" byte sized type that doesn't have that
> exemption (I think they are adding one in the newest Standard, but
> that is a very new addition.  Remember, int_least8_t is likely a
> typedef to signed char so still gets that attribute.
>
>> Third, using exact width types can have consequences for parts of
>> the code other than declarations.  In effect using exact width
>> types in one part of a program pushes the program into a mode
>> where exact width types more or less have to be used everywhere,
>> even when they are needed in only a few places.  Even if exact
>> width types are an acceptable choice, in most cases they are not
>> the best choice.
>
> As I pointed out, this method is used when you can assume the
> architecture supports those types.  Except for buffers and the
> like passed by pointers (which likely should be void* or the exact
> size likely IS important) since these types are just typedefs,
> calling a routine defined to take a int_least16_t can easily be
> called with a int16_t parameter with NO problem.
>
>> In summary, I think a better statement is that [u]intN_t is the
>> laziest way to achieve what may not be a good result, and often
>> is a suboptimal result.  The sad thing is that better techniques
>> don't need a lot of overhead;  there is a small upfront cost, but
>> once that initial cost has been paid the incremental cost is
>> basically zero.
>
> That exact same arguement is what causes some people to do things
> like
>
> #define F for
> #define R return
> ...
> and get obfuscated code.

I don't think so.  Similar arguments maybe, but certainly not
exactly the same.

> The big issue with user type like u8 is that this becomes a risk in
> library code that needs to be able to move to other projects.
>
> I would disagree that they "often" result is "suboptimal" results, as
> it looks like you methods end up with EXACTLY the same fundamental
> types being uses in the normal case, so there as no suboptimal.
>
> Yes, if your goal is "maximum portability" to unusual architectures,
> you need to be a bit more careful.
>
>>> Perhaps instead of making the type least_intN_t/fast_intN_t/intN_t
>>> they were defined instead as intN_t/fast_intN_t/exact_intN_t, or
>>> least_intN_t/intN_t/exact_intN_t so the simple name was one of the
>>> promised to exist types that might be bigger if needed, the short name
>>> bias would have lead to better code, but that ship has sailed.
>>
>> Something that hasn't come up (I think) in the discussion of
>> various type choices is the distinction between types and the
>> names of types.  In the code that I posted, the types used are
>> unsigned char and unsigned int.  To help the discussion I put in
>> some typedefs to give the names UC and UI to these types, but
>> that doesn't change what the underlying types are.  One problem
>> with the types in <stdint.h> is we don't know whether these names
>> refer to existing (standard) types, or whether they refer to
>> non-standard extended types.  Are they fish or fowl?  We don't
>> know.  That uncertainty can cause difficulties in code that uses
>> some <stdint.h> types.  For the most part I usually avoid using
>> any <stdint.h> types, for this reason and also for the reasons
>> explained above.
>
> Does it matter if they are "standard" types of not?
>
> Again, my premise was that I KNEW my code was going to run on a
> "Standard" 8 bit byte, twos complement machine with all the normal
> assumptions, because other parts were something somewhat machine
> specific.
>
> Yes, if you are writting maximally compatible code that might end up
> on something like a DSP where that doesn't hold, don't do it that way.

ISTM your argument boils down to, because a bunch of other
people used the exact-width types wrongly, that I should
also.  Other people may find such an argument convincing,
but I do not.

Thread

Beginner....Decimal/Octal converter help ManyBeers <markzuffi@yahoo.com> - 2022-09-08 11:34 -0700
  Re: Beginner....Decimal/Octal converter help Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-09-08 11:56 -0700
  Re: Beginner....Decimal/Octal converter help Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-09-08 20:19 +0100
  Re: Beginner....Decimal/Octal converter help Barry Schwarz <schwarzb@delq.com> - 2022-09-08 12:34 -0700
  Re: Beginner....Decimal/Octal converter help Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2022-09-08 20:38 -0600
  Re: Beginner....Decimal/Octal converter help Öö Tiib <ootiib@hot.ee> - 2022-09-09 03:22 -0700
    Re: Beginner....Decimal/Octal converter help gazelle@shell.xmission.com (Kenny McCormack) - 2022-09-09 13:30 +0000
  Re: Beginner....Decimal/Octal converter help Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-09-09 09:16 -0700
    Re: Beginner....Decimal/Octal converter help scott@slp53.sl.home (Scott Lurndal) - 2022-09-09 19:06 +0000
      Re: Beginner....Decimal/Octal converter help David Brown <david.brown@hesbynett.no> - 2022-09-10 11:58 +0200
        Re: Beginner....Decimal/Octal converter help Bart <bc@freeuk.com> - 2022-09-10 11:37 +0100
          Re: Beginner....Decimal/Octal converter help David Brown <david.brown@hesbynett.no> - 2022-09-10 13:05 +0200
          Re: Beginner....Decimal/Octal converter help scott@slp53.sl.home (Scott Lurndal) - 2022-09-10 14:42 +0000
            Re: Beginner....Decimal/Octal converter help Bart <bc@freeuk.com> - 2022-09-10 16:10 +0100
              Re: Beginner....Decimal/Octal converter help David Brown <david.brown@hesbynett.no> - 2022-09-10 18:14 +0200
        Re: Beginner....Decimal/Octal converter help Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-09-10 12:54 +0100
          Re: Beginner....Decimal/Octal converter help David Brown <david.brown@hesbynett.no> - 2022-09-10 16:22 +0200
            Re: Beginner....Decimal/Octal converter help Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-09-10 19:03 +0100
              Re: Beginner....Decimal/Octal converter help Bart <bc@freeuk.com> - 2022-09-10 19:30 +0100
                Re: Beginner....Decimal/Octal converter help Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-09-10 19:47 +0100
                Re: Beginner....Decimal/Octal converter help David Brown <david.brown@hesbynett.no> - 2022-09-11 14:07 +0200
                Re: Beginner....Decimal/Octal converter help Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-09-11 16:12 +0100
                Re: Beginner....Decimal/Octal converter help David Brown <david.brown@hesbynett.no> - 2022-09-11 17:58 +0200
                Re: Beginner....Decimal/Octal converter help Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-09-11 21:14 +0100
                Re: Beginner....Decimal/Octal converter help Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-09-11 20:01 -0700
                Re: Beginner....Decimal/Octal converter help Richard Damon <Richard@Damon-Family.org> - 2022-09-11 23:32 -0400
                Re: Beginner....Decimal/Octal converter help scott@slp53.sl.home (Scott Lurndal) - 2022-09-12 13:52 +0000
                Re: Beginner....Decimal/Octal converter help Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-09-14 03:24 -0700
                Re: Beginner....Decimal/Octal converter help Richard Damon <Richard@Damon-Family.org> - 2022-09-14 08:10 -0400
                Re: Beginner....Decimal/Octal converter help Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-12-26 06:09 -0800
                Re: Beginner....Decimal/Octal converter help David Brown <david.brown@hesbynett.no> - 2022-09-12 16:53 +0200
                Re: Beginner....Decimal/Octal converter help Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-09-12 16:48 +0100
                Re: Beginner....Decimal/Octal converter help Bart <bc@freeuk.com> - 2022-09-12 17:46 +0100
                Re: Beginner....Decimal/Octal converter help Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-09-12 20:37 +0100
                Re: Beginner....Decimal/Octal converter help Bart <bc@freeuk.com> - 2022-09-13 00:03 +0100
                Re: Beginner....Decimal/Octal converter help David Brown <david.brown@hesbynett.no> - 2022-09-13 12:31 +0200
                Re: Beginner....Decimal/Octal converter help Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-09-13 12:48 +0100
                Re: Beginner....Decimal/Octal converter help Bart <bc@freeuk.com> - 2022-09-13 14:18 +0100
                Re: Beginner....Decimal/Octal converter help Anton Shepelev <anton.txt@g{oogle}mail.com> - 2022-09-13 17:13 +0300
                Re: Beginner....Decimal/Octal converter help Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-09-13 16:50 +0100
                Re: Beginner....Decimal/Octal converter help Bart <bc@freeuk.com> - 2022-09-13 18:47 +0100
                Re: Beginner....Decimal/Octal converter help Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-09-14 03:16 +0100
                Re: Beginner....Decimal/Octal converter help David Brown <david.brown@hesbynett.no> - 2022-09-13 20:15 +0200
                Re: Beginner....Decimal/Octal converter help Kaz Kylheku <480-992-1380@kylheku.com> - 2022-09-13 20:29 +0000
                Re: Beginner....Decimal/Octal converter help Bart <bc@freeuk.com> - 2022-09-13 22:22 +0100
                Re: Beginner....Decimal/Octal converter help Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-09-13 14:37 -0700
                Re: Beginner....Decimal/Octal converter help Bart <bc@freeuk.com> - 2022-09-13 23:16 +0100
                Re: Beginner....Decimal/Octal converter help scott@slp53.sl.home (Scott Lurndal) - 2022-09-13 22:16 +0000
                Re: Beginner....Decimal/Octal converter help Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-09-13 16:15 -0700
                Re: Beginner....Decimal/Octal converter help Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-09-13 16:15 -0700
                Re: Beginner....Decimal/Octal converter help Bart <bc@freeuk.com> - 2022-09-14 10:58 +0100
                Re: Beginner....Decimal/Octal converter help Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-09-14 15:36 +0100
                Re: Beginner....Decimal/Octal converter help Richard Harnden <richard.nospam@gmail.com> - 2022-09-14 21:53 +0100
                Re: Beginner....Decimal/Octal converter help Kaz Kylheku <480-992-1380@kylheku.com> - 2022-09-14 05:55 +0000
                Re: Beginner....Decimal/Octal converter help David Brown <david.brown@hesbynett.no> - 2022-09-14 10:10 +0200
                Re: Beginner....Decimal/Octal converter help Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-09-14 07:54 -0700
                Re: Beginner....Decimal/Octal converter help David Brown <david.brown@hesbynett.no> - 2022-09-14 18:32 +0200
                Re: Beginner....Decimal/Octal converter help Bart <bc@freeuk.com> - 2022-09-14 18:39 +0100
                Re: Beginner....Decimal/Octal converter help Kaz Kylheku <480-992-1380@kylheku.com> - 2022-09-15 01:12 +0000
                Re: Beginner....Decimal/Octal converter help David Brown <david.brown@hesbynett.no> - 2022-09-15 09:11 +0200
                Re: Beginner....Decimal/Octal converter help Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-09-15 08:07 -0700
                Re: Beginner....Decimal/Octal converter help Kaz Kylheku <480-992-1380@kylheku.com> - 2022-09-14 18:40 +0000
                Re: Beginner....Decimal/Octal converter help Kaz Kylheku <480-992-1380@kylheku.com> - 2022-09-14 05:45 +0000
                Re: Beginner....Decimal/Octal converter help Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-09-14 12:11 +0100
                Re: Beginner....Decimal/Octal converter help David Brown <david.brown@hesbynett.no> - 2022-09-14 09:57 +0200
                Re: Beginner....Decimal/Octal converter help Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-09-14 03:09 +0100
                Re: Beginner....Decimal/Octal converter help David Brown <david.brown@hesbynett.no> - 2022-09-14 10:29 +0200
                Re: Beginner....Decimal/Octal converter help Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-09-14 15:14 +0100
                Re: Beginner....Decimal/Octal converter help Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-09-14 07:36 -0700
                Re: Beginner....Decimal/Octal converter help Öö Tiib <ootiib@hot.ee> - 2022-10-03 01:10 -0700
                Re: Beginner....Decimal/Octal converter help Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-10-03 11:36 +0100
                Re: Beginner....Decimal/Octal converter help Öö Tiib <ootiib@hot.ee> - 2022-10-04 02:13 -0700
                Re: Beginner....Decimal/Octal converter help Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-10-04 16:27 +0100
                Re: Beginner....Decimal/Octal converter help Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-09-13 11:48 -0700
                Re: Beginner....Decimal/Octal converter help David Brown <david.brown@hesbynett.no> - 2022-09-14 10:38 +0200
                Re: Beginner....Decimal/Octal converter help scott@slp53.sl.home (Scott Lurndal) - 2022-09-14 14:27 +0000
                Re: Beginner....Decimal/Octal converter help Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-09-14 07:58 -0700
                Re: Beginner....Decimal/Octal converter help Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-09-16 13:06 -0700
                Re: Beginner....Decimal/Octal converter help Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-09-16 13:16 -0700
                Re: Beginner....Decimal/Octal converter help scott@slp53.sl.home (Scott Lurndal) - 2022-09-12 17:55 +0000
                Re: Beginner....Decimal/Octal converter help Kaz Kylheku <480-992-1380@kylheku.com> - 2022-09-12 18:22 +0000
                Re: Beginner....Decimal/Octal converter help Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-09-12 20:41 +0100
                Re: Beginner....Decimal/Octal converter help Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-09-11 15:45 -0700
                Re: Beginner....Decimal/Octal converter help Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-09-11 15:41 -0700
                Re: Beginner....Decimal/Octal converter help David Brown <david.brown@hesbynett.no> - 2022-09-12 17:06 +0200
              Re: Beginner....Decimal/Octal converter help Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-09-11 06:46 -0700
          Re: Beginner....Decimal/Octal converter help Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-09-11 06:57 -0700
      Re: Beginner....Decimal/Octal converter help Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-09-11 07:07 -0700
        Neologism (Was: Beginner....Decimal/Octal converter help) gazelle@shell.xmission.com (Kenny McCormack) - 2022-09-11 14:18 +0000
        Re: Beginner....Decimal/Octal converter help scott@slp53.sl.home (Scott Lurndal) - 2022-09-11 16:33 +0000
          Re: Beginner....Decimal/Octal converter help Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-09-13 15:40 -0700
  Re: Beginner....Decimal/Octal converter help scott@slp53.sl.home (Scott Lurndal) - 2022-09-09 23:08 +0000
    Re: Beginner....Decimal/Octal converter help Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-09-11 06:37 -0700
      Re: Beginner....Decimal/Octal converter help scott@slp53.sl.home (Scott Lurndal) - 2022-09-11 16:31 +0000
        Re: Beginner....Decimal/Octal converter help Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-09-13 15:44 -0700

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