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Re: What is your opinion about unsigned int u = -2 ?

From Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups comp.lang.c
Subject Re: What is your opinion about unsigned int u = -2 ?
Date 2024-08-11 12:33 -0700
Organization A noiseless patient Spider
Message-ID <86y152n9c8.fsf@linuxsc.com> (permalink)
References <v8dfo9$1k7cg$1@dont-email.me> <87mslxe4wj.fsf@bsb.me.uk>

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Ben Bacarisse <ben@bsb.me.uk> writes:

> Thiago Adams <thiago.adams@gmail.com> writes:
>
>> What is your opinion about this:
>>
>> unsigned int u1 = -1;
>>
>> Generally -1 is used to get the maximum value.
>
> Yes, that's a common usage, though I prefer either -1u or ~0u.
>
>> Is this guaranteed to work?
>>
>> How about this one?
>>
>> unsigned int u2 = -2;
>> Does it makes sense?  Maybe a warning here?
>
> Warnings are almost always good, especially if they can be configured.
> For example you can ask gcc to warn about converting -1 to unsigned
> while leaving -1u and ~0u alone.

Ick.  That choice is exactly backwards IMO.  Converting -1 to
an unsigned type always sets all the bits.  Converting -1u to
an unsigned type can easily do the wrong thing, depending
on the target type.

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Thread

What is your opinion about unsigned int u = -2 ? Thiago Adams <thiago.adams@gmail.com> - 2024-07-31 10:55 -0300
  Re: What is your opinion about unsigned int u = -2 ? Ben Bacarisse <ben@bsb.me.uk> - 2024-07-31 20:29 +0100
    Re: What is your opinion about unsigned int u = -2 ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-11 12:33 -0700
      Re: What is your opinion about unsigned int u = -2 ? Vir Campestris <vir.campestris@invalid.invalid> - 2024-08-11 21:08 +0100
        Re: What is your opinion about unsigned int u = -2 ? Richard Damon <richard@damon-family.org> - 2024-08-11 16:45 -0400
        Re: What is your opinion about unsigned int u = -2 ? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-08-11 16:53 -0400
          Re: What is your opinion about unsigned int u = -2 ? Vir Campestris <vir.campestris@invalid.invalid> - 2024-08-12 11:47 +0100
        Re: What is your opinion about unsigned int u = -2 ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-11 23:07 -0700
  Re: What is your opinion about unsigned int u = -2 ? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-07-31 17:17 -0400
  Re: What is your opinion about unsigned int u = -2 ? Blue-Maned_Hawk <bluemanedhawk@invalid.invalid> - 2024-08-01 06:34 +0000
    Re: What is your opinion about unsigned int u = -2 ? Ben Bacarisse <ben@bsb.me.uk> - 2024-08-01 12:02 +0100
      Re: What is your opinion about unsigned int u = -2 ? Thiago Adams <thiago.adams@gmail.com> - 2024-08-02 10:36 -0300
        Re: What is your opinion about unsigned int u = -2 ? gazelle@shell.xmission.com (Kenny McCormack) - 2024-08-02 14:33 +0000
          Re: What is your opinion about unsigned int u = -2 ? Bart <bc@freeuk.com> - 2024-08-02 15:48 +0100
            Re: What is your opinion about unsigned int u = -2 ? Ben Bacarisse <ben@bsb.me.uk> - 2024-08-02 16:17 +0100
            Re: What is your opinion about unsigned int u = -2 ? Thiago Adams <thiago.adams@gmail.com> - 2024-08-02 15:39 -0300
              Re: What is your opinion about unsigned int u = -2 ? Thiago Adams <thiago.adams@gmail.com> - 2024-08-02 15:58 -0300
            Re: What is your opinion about unsigned int u = -2 ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-02 11:48 -0700
              Re: What is your opinion about unsigned int u = -2 ? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-08-02 15:21 -0400
                Re: What is your opinion about unsigned int u = -2 ? Thiago Adams <thiago.adams@gmail.com> - 2024-08-02 22:03 -0300
                Re: What is your opinion about unsigned int u = -2 ? Thiago Adams <thiago.adams@gmail.com> - 2024-08-02 22:12 -0300
                Re: What is your opinion about unsigned int u = -2 ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-02 18:31 -0700
                Re: What is your opinion about unsigned int u = -2 ? Thiago Adams <thiago.adams@gmail.com> - 2024-08-02 22:50 -0300
                Re: What is your opinion about unsigned int u = -2 ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-02 19:29 -0700
                Re: What is your opinion about unsigned int u = -2 ? Thiago Adams <thiago.adams@gmail.com> - 2024-08-03 09:36 -0300
                Re: What is your opinion about unsigned int u = -2 ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-03 16:10 -0700
                Re: What is your opinion about unsigned int u = -2 ? Thiago Adams <thiago.adams@gmail.com> - 2024-08-03 22:46 -0300
                Re: What is your opinion about unsigned int u = -2 ? Thiago Adams <thiago.adams@gmail.com> - 2024-08-03 23:04 -0300
                Re: What is your opinion about unsigned int u = -2 ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-02 18:25 -0700
                Re: What is your opinion about unsigned int u = -2 ? Thiago Adams <thiago.adams@gmail.com> - 2024-08-02 22:44 -0300
                Re: What is your opinion about unsigned int u = -2 ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-02 19:04 -0700
                Re: What is your opinion about unsigned int u = -2 ? Thiago Adams <thiago.adams@gmail.com> - 2024-08-02 23:27 -0300
                Re: What is your opinion about unsigned int u = -2 ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-02 19:40 -0700
                Re: What is your opinion about unsigned int u = -2 ? David Brown <david.brown@hesbynett.no> - 2024-08-03 19:43 +0200
                Re: What is your opinion about unsigned int u = -2 ? Thiago Adams <thiago.adams@gmail.com> - 2024-08-03 14:46 -0300
                Re: What is your opinion about unsigned int u = -2 ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-03 16:52 -0700
                Re: What is your opinion about unsigned int u = -2 ? dave_thompson_2@comcast.net - 2024-08-25 16:52 -0400
                Re: What is your opinion about unsigned int u = -2 ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-25 14:28 -0700
                Re: What is your opinion about unsigned int u = -2 ? David Brown <david.brown@hesbynett.no> - 2024-08-03 19:34 +0200
                Re: What is your opinion about unsigned int u = -2 ? Thiago Adams <thiago.adams@gmail.com> - 2024-08-03 14:51 -0300
                Re: What is your opinion about unsigned int u = -2 ? Thiago Adams <thiago.adams@gmail.com> - 2024-08-03 15:30 -0300
                Re: What is your opinion about unsigned int u = -2 ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-03 16:46 -0700
                Re: What is your opinion about unsigned int u = -2 ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-11 13:57 -0700
                Re: What is your opinion about unsigned int u = -2 ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-11 14:53 -0700
                Re: What is your opinion about unsigned int u = -2 ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-03 16:19 -0700
              Re: What is your opinion about unsigned int u = -2 ? Bonita Montero <Bonita.Montero@gmail.com> - 2024-08-09 20:10 +0200
            Re: What is your opinion about unsigned int u = -2 ? David Brown <david.brown@hesbynett.no> - 2024-08-03 19:17 +0200
          Re: What is your opinion about unsigned int u = -2 ? Bonita Montero <Bonita.Montero@gmail.com> - 2024-08-04 20:29 +0200
            Re: What is your opinion about unsigned int u = -2 ? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-08-07 23:48 +0000
              Re: What is your opinion about unsigned int u = -2 ? David Brown <david.brown@hesbynett.no> - 2024-08-08 19:47 +0200
                Re: What is your opinion about unsigned int u = -2 ? Bonita Montero <Bonita.Montero@gmail.com> - 2024-08-09 20:08 +0200
                Re: What is your opinion about unsigned int u = -2 ? David Brown <david.brown@hesbynett.no> - 2024-08-09 20:19 +0200
                Re: What is your opinion about unsigned int u = -2 ? Bonita Montero <Bonita.Montero@gmail.com> - 2024-08-09 21:18 +0200
                Re: What is your opinion about unsigned int u = -2 ? David Brown <david.brown@hesbynett.no> - 2024-08-09 21:40 +0200
                Re: What is your opinion about unsigned int u = -2 ? Richard Damon <richard@damon-family.org> - 2024-08-09 21:16 -0400
    Re: What is your opinion about unsigned int u = -2 ? Bonita Montero <Bonita.Montero@gmail.com> - 2024-08-04 18:16 +0200

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