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Re: signed vs unsigned and gcc -Wsign-conversion

From David Brown <david.brown@hesbynett.no>
Newsgroups comp.lang.c
Subject Re: signed vs unsigned and gcc -Wsign-conversion
Date 2025-10-21 09:13 +0200
Organization A noiseless patient Spider
Message-ID <10d7br2$3o6i0$1@dont-email.me> (permalink)
References <10d5j0v$3kdmk$1@dont-email.me> <20251020194337.000029ab@yahoo.com> <2OuJQ.346589$Tux4.230279@fx11.iad>

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On 20/10/2025 20:01, Scott Lurndal wrote:
> Michael S <already5chosen@yahoo.com> writes:
>> On Mon, 20 Oct 2025 17:03:58 +0200
>> pozz <pozzugno@gmail.com> wrote:
>>
>>> After many years programming in C language, I'm always unsure if it
>>> is safer to use signed int or unsigned int.
>>>
>>> Of course there are situations where signed or unsigned is clearly
>>> better. For example, if the values could assume negative values,
>>> signed int is the only solution. If you are manipulating single bits
>>> (&, |, ^, <<, >>), unsigned ints are your friends.
>>>
>>> What about other situations? For example, what do you use for the "i"
>>> loop variable?
>>>
>>
>> I'd just point out that small negative numbers are FAR more common than
>> numbers in range [2**31..2**32-1].
>> Now, make your own conclusion.
> 
> One might also point out that negative loop indicies are rare, and
> thus ones conclusion may be that generally speaking loop indexes should
> be unsigned.
> 

Loop indicies greater than 2 ^ 31 are equally rare.  (Loops of between 2 
^ 15 and 2 ^ 16 - 1 on 8-bit and 16-bit targets are less unrealistic.)

Loops where you actually want the index counter to wrap are very rare, 
except perhaps when your loop is shifting the index each count (and then 
you are firmly in unsigned type territory).

So in general, you are dealing with numbers that will fit comfortably 
within the ranges of both "int" and "unsigned int".  If there is no 
other deciding factor, pick the one with the fewest unnecessary 
additional specifications, since that gives the compiler the most 
flexibility - "int".

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signed vs unsigned and gcc -Wsign-conversion pozz <pozzugno@gmail.com> - 2025-10-20 17:03 +0200
  Re: signed vs unsigned and gcc -Wsign-conversion Bonita Montero <Bonita.Montero@gmail.com> - 2025-10-20 17:38 +0200
  Re: signed vs unsigned and gcc -Wsign-conversion Michael S <already5chosen@yahoo.com> - 2025-10-20 19:43 +0300
    Re: signed vs unsigned and gcc -Wsign-conversion Bonita Montero <Bonita.Montero@gmail.com> - 2025-10-20 19:07 +0200
    Re: signed vs unsigned and gcc -Wsign-conversion scott@slp53.sl.home (Scott Lurndal) - 2025-10-20 18:01 +0000
      Re: signed vs unsigned and gcc -Wsign-conversion Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-10-21 04:27 +0200
      Re: signed vs unsigned and gcc -Wsign-conversion David Brown <david.brown@hesbynett.no> - 2025-10-21 09:13 +0200
    Re: signed vs unsigned and gcc -Wsign-conversion BGB <cr88192@gmail.com> - 2025-10-20 17:44 -0500
    Re: signed vs unsigned and gcc -Wsign-conversion Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-10-20 23:36 +0000
      Re: signed vs unsigned and gcc -Wsign-conversion Kaz Kylheku <643-408-1753@kylheku.com> - 2025-10-20 23:52 +0000
      Re: signed vs unsigned and gcc -Wsign-conversion Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-10-20 16:58 -0700
  Re: signed vs unsigned and gcc -Wsign-conversion David Brown <david.brown@hesbynett.no> - 2025-10-20 20:03 +0200
    Re: signed vs unsigned and gcc -Wsign-conversion Kaz Kylheku <643-408-1753@kylheku.com> - 2025-10-20 20:09 +0000
      Re: signed vs unsigned and gcc -Wsign-conversion rbowman <bowman@montana.com> - 2025-10-21 01:43 +0000
      Re: signed vs unsigned and gcc -Wsign-conversion David Brown <david.brown@hesbynett.no> - 2025-10-21 12:42 +0200
        Re: signed vs unsigned and gcc -Wsign-conversion James Kuyper <jameskuyper@alumni.caltech.edu> - 2025-10-21 14:44 -0400
          Re: signed vs unsigned and gcc -Wsign-conversion David Brown <david.brown@hesbynett.no> - 2025-10-21 22:56 +0200
  Re: signed vs unsigned and gcc -Wsign-conversion Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-10-20 14:48 -0700
    Re: signed vs unsigned and gcc -Wsign-conversion Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-10-20 17:13 -0700
      Re: signed vs unsigned and gcc -Wsign-conversion Kaz Kylheku <643-408-1753@kylheku.com> - 2025-10-21 01:45 +0000
        Re: signed vs unsigned and gcc -Wsign-conversion antispam@fricas.org (Waldek Hebisch) - 2025-10-21 03:52 +0000
  Re: signed vs unsigned and gcc -Wsign-conversion Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-10-20 23:35 +0000
    Re: signed vs unsigned and gcc -Wsign-conversion Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-10-20 23:38 +0000
      Re: signed vs unsigned and gcc -Wsign-conversion Bonita Montero <Bonita.Montero@gmail.com> - 2025-10-21 09:57 +0200
        Re: signed vs unsigned and gcc -Wsign-conversion Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-10-21 19:45 +0000
  Re: signed vs unsigned and gcc -Wsign-conversion antispam@fricas.org (Waldek Hebisch) - 2025-10-21 04:42 +0000
  Re: signed vs unsigned and gcc -Wsign-conversion Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-12-15 00:25 -0800

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