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Re: is there a way to ask a variable what it is?

From Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups comp.lang.c
Subject Re: is there a way to ask a variable what it is?
Date 2020-02-18 08:56 -0800
Organization A noiseless patient Spider
Message-ID <86lfozeswm.fsf@linuxsc.com> (permalink)
References <r0qtkb$3qj$1@dont-email.me> <h9cfvbF25s3U14@mid.individual.net> <r0r37k$r04$1@dont-email.me> <87zhe5pzqf.fsf@bsb.me.uk>

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

> [...] C is a statically typed language so all type information,
> and everything easily derived from type information, is known at
> compile time.

I don't think that's right exactly.  For one example, some type
information may be known in one translation unit but not known
in another.  A declaration like

    extern int special_values[];

offers partial but not complete type information in this TU, and so
is not known at compile time.  A second example is variable length
arrays.  Here the type information is not known until run time, and
usually is not fixed but varies with different invocations.  A third
example pertains to structures and unions in dynamically allocated
memory, where code inspects a tag using the "one special guarantee"
for structure member access, to select a specific struct type (using
a cast) at run time.  Certainly there are other examples but I think
these provide enough variety and flavor to motivate the objection.

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Thread

is there a way to ask a variable what it is? T <T@invalid.invalid> - 2020-01-28 19:19 -0800
  Re: is there a way to ask a variable what it is? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-01-29 03:47 +0000
    Re: is there a way to ask a variable what it is? T <T@invalid.invalid> - 2020-01-28 20:20 -0800
      Re: is there a way to ask a variable what it is? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-01-29 19:18 +0000
        Re: is there a way to ask a variable what it is? Bart <bc@freeuk.com> - 2020-01-29 20:58 +0000
          Re: is there a way to ask a variable what it is? nobody@example.org (Scott) - 2020-01-30 15:59 +0000
            Re: is there a way to ask a variable what it is? scott@slp53.sl.home (Scott Lurndal) - 2020-01-30 16:35 +0000
    Re: is there a way to ask a variable what it is? Siri Cruise <chine.bleu@yahoo.com> - 2020-01-28 21:55 -0800
      Re: is there a way to ask a variable what it is? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-01-30 00:24 +0000
        solved: Re: is there a way to ask a variable what it is? T <T@invalid.invalid> - 2020-01-29 21:51 -0800
          Re: solved: Re: is there a way to ask a variable what it is? fir <profesor.fir@gmail.com> - 2020-01-30 03:16 -0800
  Re: is there a way to ask a variable what it is? Ian Collins <ian-news@hotmail.com> - 2020-01-29 17:28 +1300
    Re: is there a way to ask a variable what it is? T <T@invalid.invalid> - 2020-01-28 20:55 -0800
      Re: is there a way to ask a variable what it is? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-01-29 06:49 +0000
      Re: is there a way to ask a variable what it is? Bonita Montero <Bonita.Montero@gmail.com> - 2020-01-29 08:08 +0100
      Re: is there a way to ask a variable what it is? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-01-30 00:14 +0000
        solved: Re: is there a way to ask a variable what it is? T <T@invalid.invalid> - 2020-01-29 21:51 -0800
        Re: is there a way to ask a variable what it is? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-18 08:56 -0800
          Re: is there a way to ask a variable what it is? already5chosen@yahoo.com - 2020-02-19 01:19 -0800
            Re: is there a way to ask a variable what it is? chad <cdalten@gmail.com> - 2020-02-19 02:53 -0800
            Re: is there a way to ask a variable what it is? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-19 12:45 +0000
            Re: is there a way to ask a variable what it is? James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-19 07:55 -0500
            Re: is there a way to ask a variable what it is? Bart <bc@freeuk.com> - 2020-02-19 13:02 +0000
              Re: is there a way to ask a variable what it is? chad <cdalten@gmail.com> - 2020-02-19 07:27 -0800
            Re: is there a way to ask a variable what it is? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-22 09:42 -0800
  Re: is there a way to ask a variable what it is? Robert Wessel <robertwessel2@yahoo.com> - 2020-01-28 22:36 -0600
    Re: is there a way to ask a variable what it is? T <T@invalid.invalid> - 2020-01-28 20:55 -0800
      Re: is there a way to ask a variable what it is? Manfred <noname@add.invalid> - 2020-01-29 13:22 +0100
        Re: is there a way to ask a variable what it is? David Brown <david.brown@hesbynett.no> - 2020-01-29 13:57 +0100
          Re: is there a way to ask a variable what it is? Manfred <noname@add.invalid> - 2020-01-29 17:47 +0100
            Re: is there a way to ask a variable what it is? David Brown <david.brown@hesbynett.no> - 2020-01-30 12:06 +0100
    Re: is there a way to ask a variable what it is? scott@slp53.sl.home (Scott Lurndal) - 2020-01-29 15:10 +0000
      Re: is there a way to ask a variable what it is? Manfred <noname@add.invalid> - 2020-01-29 17:07 +0100
  Re: is there a way to ask a variable what it is? Siri Cruise <chine.bleu@yahoo.com> - 2020-01-28 21:52 -0800
  Re: is there a way to ask a variable what it is? Bart <bc@freeuk.com> - 2020-01-29 11:11 +0000
    Re: is there a way to ask a variable what it is? Bonita Montero <Bonita.Montero@gmail.com> - 2020-01-29 13:30 +0100
      Re: is there a way to ask a variable what it is? Bart <bc@freeuk.com> - 2020-01-29 12:44 +0000
        Re: is there a way to ask a variable what it is? Bonita Montero <Bonita.Montero@gmail.com> - 2020-01-29 14:03 +0100
          Re: is there a way to ask a variable what it is? gazelle@shell.xmission.com (Kenny McCormack) - 2020-01-29 14:03 +0000
          Re: is there a way to ask a variable what it is? Bart <bc@freeuk.com> - 2020-01-29 14:30 +0000
            Re: is there a way to ask a variable what it is? Bonita Montero <Bonita.Montero@gmail.com> - 2020-01-29 15:45 +0100
              Re: is there a way to ask a variable what it is? Bonita Montero <Bonita.Montero@gmail.com> - 2020-01-29 16:28 +0100
                Re: is there a way to ask a variable what it is? T <T@invalid.invalid> - 2020-01-29 08:35 -0800
                Re: is there a way to ask a variable what it is? Bart <bc@freeuk.com> - 2020-01-29 17:34 +0000
                Re: is there a way to ask a variable what it is? Bonita Montero <Bonita.Montero@gmail.com> - 2020-01-29 18:48 +0100
    Re: is there a way to ask a variable what it is? Thiago Adams <thiago.adams@gmail.com> - 2020-01-29 04:43 -0800
      Re: is there a way to ask a variable what it is? David Brown <david.brown@hesbynett.no> - 2020-01-29 14:46 +0100
        Re: is there a way to ask a variable what it is? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-01-29 15:15 +0000
          Re: is there a way to ask a variable what it is? fir <profesor.fir@gmail.com> - 2020-01-29 08:11 -0800
          Re: is there a way to ask a variable what it is? T <T@invalid.invalid> - 2020-01-29 08:38 -0800
  Re: is there a way to ask a variable what it is? Bart <bc@freeuk.com> - 2020-01-29 11:23 +0000
  Re: is there a way to ask a variable what it is? John Bode <jfbode1029@gmail.com> - 2020-01-29 11:55 -0800
  Re: is there a way to ask a variable what it is? jacobnavia <jacob@jacob.remcomp.fr> - 2020-02-19 12:23 +0100
  Re: is there a way to ask a variable what it is? jacobnavia <jacob@jacob.remcomp.fr> - 2020-02-19 12:23 +0100

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