Re: Why does the -> operator exist ?

From	Ben Bacarisse <ben.usenet@bsb.me.uk>
Newsgroups	comp.lang.c
Subject	Re: Why does the -> operator exist ?
Date	2023-06-27 18:01 +0100
Organization	A noiseless patient Spider
Message-ID	<874jmsq1p7.fsf@bsb.me.uk> (permalink)
References	<trfLpf+N71iCzEwJm@bongo-ra.co> <u7etsq$1e0jo$1@dont-email.me>

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Bart <bc@freeuk.com> writes:

> On 27/06/2023 10:12, Spiros Bousbouras wrote:
>> I mean would it create an ambiguity if you could write  s.field
>> both when  s  is a structure or union and when  s  is a pointer
>> to a structure or union ?
>
> I thought you meant why C allows P->m since it does exactly the same thing
> as (*P).m.
>
> From your other comment, you are asking why have a dereference between P
> and m at all.
>
> Actually this could have been made optional in this case:
>
>       struct S* P;
>       struct S  Q;
>
>       P.m + Q.m;  // compiler transforms this to (*P).m + Q.m;
>
> You lose some transparency, but reduce clutter and improve readability by
> not having to type (*P).m or P->m.
>
> However you will still need it in other contexts such as:
>
>       P;
>
> is this evaluating the pointer, or the struct it points to?

The suggestion, I think, was simply to all . on a struct pointer instead
of requiring ->.

> Here you need
> to choose between P and *P (-> doesn't help here: there is no member).

-- 
Ben.

Thread

Why does the  ->  operator exist ? Spiros Bousbouras <spibou@gmail.com> - 2023-06-27 09:12 +0000
  Re: Why does the  ->  operator exist ? felix@palmen-it.de (Felix Palmen) - 2023-06-27 15:01 +0200
    Re: Why does the  ->  operator exist ? Spiros Bousbouras <spibou@gmail.com> - 2023-06-27 14:09 +0000
      Re: Why does the  ->  operator exist ? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2023-06-27 15:56 +0100
  Re: Why does the -> operator exist ? Bart <bc@freeuk.com> - 2023-06-27 16:06 +0100
    Re: Why does the -> operator exist ? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2023-06-27 18:01 +0100
      Re: Why does the -> operator exist ? BGB <cr88192@gmail.com> - 2023-06-27 12:46 -0500
    Re: Why does the -> operator exist ? fir <profesor.fir@gmail.com> - 2023-08-09 00:08 -0700
      Re: Why does the -> operator exist ? fir <profesor.fir@gmail.com> - 2023-08-09 00:11 -0700
        Re: Why does the -> operator exist ? fir <profesor.fir@gmail.com> - 2023-08-09 00:23 -0700
  Re: Why does the  ->  operator exist ? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2023-06-27 15:13 +0000
  Re: Why does the  ->  operator exist ? Kaz Kylheku <864-117-4973@kylheku.com> - 2023-06-27 15:30 +0000
    Re: Why does the -> operator exist ? Bart <bc@freeuk.com> - 2023-06-27 17:05 +0100
      Re: Why does the -> operator exist ? Kaz Kylheku <864-117-4973@kylheku.com> - 2023-06-27 17:11 +0000
  Re: Why does the -> operator exist ? BGB <cr88192@gmail.com> - 2023-06-27 10:54 -0500
  Re: Why does the  ->  operator exist ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2023-06-27 12:23 -0700
    Re: Why does the  ->  operator exist ? Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2023-06-27 15:33 -0600
    Re: Why does the  ->  operator exist ? Spiros Bousbouras <spibou@gmail.com> - 2023-06-28 16:31 +0000
      Re: Why does the  ->  operator exist ? Kaz Kylheku <864-117-4973@kylheku.com> - 2023-06-29 03:14 +0000
    Re: Why does the  ->  operator exist ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-07-20 18:57 -0700
      Re: Why does the  ->  operator exist ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2023-07-20 19:49 -0700
        Re: Why does the  ->  operator exist ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-08-08 05:49 -0700
          Re: Why does the  ->  operator exist ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2023-08-08 16:33 -0700
            Re: Why does the  ->  operator exist ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-08-14 04:34 -0700
              I love it... (Was: Why does the  ->  operator exist ?) gazelle@shell.xmission.com (Kenny McCormack) - 2023-08-14 12:41 +0000
              Re: Why does the  ->  operator exist ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2023-08-14 15:10 -0700
                Re: Why does the  ->  operator exist ? Phil Carmody <pc+usenet@asdf.org> - 2023-08-15 23:00 +0300
                Re: Why does the  ->  operator exist ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-08-16 05:29 -0700
      Re: Why does the  ->  operator exist ? Kaz Kylheku <864-117-4973@kylheku.com> - 2023-07-22 05:39 +0000
  Re: Why does the -> operator exist ? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2023-06-28 14:16 -0700

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