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

From David Brown <david.brown@hesbynett.no>
Newsgroups comp.lang.c
Subject Re: Beginner....Decimal/Octal converter help
Date 2022-09-10 16:22 +0200
Organization A noiseless patient Spider
Message-ID <tfi6jk$1f9ct$1@dont-email.me> (permalink)
References <8ffd982c-2e82-4caa-9256-ec17be2efe56n@googlegroups.com> <86leqsr091.fsf@linuxsc.com> <S8MSK.400474$iiS8.244727@fx17.iad> <tfhn50$1c35d$1@dont-email.me> <875yhv30nu.fsf@bsb.me.uk>

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On 10/09/2022 13:54, Ben Bacarisse wrote:
> David Brown <david.brown@hesbynett.no> writes:
> 
>> On 09/09/2022 21:06, Scott Lurndal wrote:
>>> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
>>>> ManyBeers <markzuffi@yahoo.com> writes:
>>>>
>>>>> Hello I am teaching myself C and I need some help with a problem.
>>>>> After a search for dec/oct convert I found this code:
>>>>>
>>>>> [..code..]
>>>>
>>>> I would like to offer a different kind of answer to your
>>>> questions.  First a suggestion:  for this kind of problem I think
>>>> you will find it helpful to use unsigned types exclusively.  In
>>>> the code below we will need (besides a plain 'unsigned' here and
>>>> there) two types, one for 8-bit values and one for 32-bit values:
>>>>
>>>>    typedef unsigned char  UC;
>>>>    typedef unsigned int   UI;
>>> There already standard perfectly cromulent typedefs for both,
>>> uint8_t and uint32_t.
>>
>> And those type names are better in a number of ways.  They are
>> clearer, more precise, and hide the design flaw in C of mixing the
>> concepts of "character" and "small number".  In particular, they
>> specify exactly what size your numbers are, rather that having hidden
>> assumptions in the code.
> 
> But they both say too much.  The 'source' integer size need not be 32
> bits and, given that there are no other obvious requirements, unsigned
> int seems to me to be the natural choice.  And if the requirements were
> that 32-bit numbers could be handled, uint_least32_t (or uint_fast32_t)
> more precisely meets the need.

"unsigned int" might have been a reasonable choice, but Tim's code goes 
on to rely on it being 32-bit.  (Or to be more accurate, it /says/ it 
relies on it being 32-bit.)

> 
> And the uint8_t is also unnecessarily specific.  We do want to know that
> digits up to 255 can be stored, but nothing goes wrong if the type is
> wider.  uint_least8_t says exactly what's wanted and no more.
> 
> Mind you, since char is guaranteed to be at least 8 bits wide, unsigned
> char is effectively uint_least8_t.
> 

There is such a thing as being /too/ portable.  There are some 
real-world C implementations that do not have uint8_t and/or uint32_t, 
but the overlap in code between these niche systems and "normal" systems 
is almost non-existent.  So the use of "uint_least8_t", "uint_fast32_t" 
and similar types is IMHO needless complication and verbosity, and 
certainly not something beginners should need to bother about.  You are, 
of course, technically correct in everything you write here - but that 
still does not make these types a better choice in the circumstances. 
(Again, all in my humble opinion.)

An alternative approach would be to have typedefs that are descriptive 
and application-specific, and which can be changed later to allow 
different sizes to be converted.  Especially in light of it being code 
for someone relatively unfamiliar with the language, I'd err on the side 
of longer names (and certainly not cryptic short abbreviations that are 
not particularly relevant to the usage) :

	typedef uint8_t digit_type;
	typedef uint32_t number_type;

and perhaps :

	static const number_type max_number = -1;

if it is needed in the code later.

I'd be quite happy with "unsigned char" and "unsigned int" for these 
typedefs, if that is the programmer's preference.  But I certainly would 
not want the number 4294967296 as part of the function names!

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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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