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Groups > comp.std.c > #6039

Re: Addition of nocode keyword

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On 30/10/2019 17:47, Nick Bowler wrote:
> On Wed, 30 Oct 2019 08:12:24 -0700, jameskuyper wrote:
>> "auto" has been a keyword for longer than C has been a language. It is,
>> in fact, a carry over from one of C's predecessor languages (I'm not
>> sure whether it was introduced in B or in BCPL). It actually made more
>> sense in the predecessor language. In C, the only places where you're
>> allowed to use "auto" are places where automatic storage duration is the
>> default, so leaving out "auto" would give the same result as using it.
>> As a result, C code almost never uses "auto". Something about it's
>> predecessor language was different (I'm not sure what) that made "auto"
>> a reasonable thing to use in that language.
> 
> In B, local variables are declared like this:
> 
>    auto x;
> 
> This syntax was permitted and works basically the same way in the original
> C standards.  In this specific case, removing 'auto' in fact changes the
> meaning of the declaration (so in C90 it was not the case, in general,
> that removing "auto" would give the same result as using it).

I think that was only because of the "implicit int".  In older C, 
"implicit int" meant that "auto x;" had the same meaning as "auto int 
x;".  Removing the "auto" from that, you'd get "int x;", which would 
have exactly the same meaning (in contexts where "auto int x;" is allowed).

I haven't used B (or BCPL) - could it be that they did not have 
different types, and thus no equivalent of "int x;" ?

> 
> C99 and later standards completely removed this particular declaration
> style from the language; all remaining uses of the auto keyword are truly
> redundant.  However most modern C compilers still support this syntax
> (with the required diagnostic message) even when they implement recent
> standards.
> 

Once "implicit int" was removed from the language, you could no longer 
write "auto x;" - you had to write "auto int x;", "register int x;" or 
just "int x;" (with the auto implied) for a non-static local variable. 
As there is no benefit in including the "auto", it is rarely seen.  But 
compilers /must/ still support "auto int x;" if they try to be 
conforming, as it is still allowed even in modern standards.  And many 
still allow "auto x;" (with implicit int) when compiling in lax modes, 
for support for older code.

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Thread

Addition of nocode keyword "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-10-25 05:26 -0700
  Re: Addition of nocode keyword Philipp Klaus Krause <pkk@spth.de> - 2019-10-25 15:53 +0200
    Re: Addition of nocode keyword "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-10-25 07:26 -0700
      Re: Addition of nocode keyword Philipp Klaus Krause <pkk@spth.de> - 2020-08-04 11:00 +0200
  Re: Addition of nocode keyword "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-10-25 11:04 -0700
  Re: Addition of nocode keyword Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-25 23:42 +0100
    Re: Addition of nocode keyword "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-10-25 22:20 -0400
      Re: Addition of nocode keyword Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-26 22:52 +0100
        Re: Addition of nocode keyword Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-26 23:27 +0100
        Re: Addition of nocode keyword "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-10-26 17:19 -0700
  Re: Addition of nocode keyword Richard Damon <Richard@Damon-Family.org> - 2019-10-25 22:10 -0300
    Re: Addition of nocode keyword "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-10-25 19:02 -0700
      Re: Addition of nocode keyword Richard Damon <Richard@Damon-Family.org> - 2019-10-28 23:45 -0400
        Re: Addition of nocode keyword "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-10-29 08:15 -0400
          Re: Addition of nocode keyword "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-10-29 08:42 -0400
          Re: Addition of nocode keyword Richard Damon <Richard@Damon-Family.org> - 2019-10-29 22:37 -0400
            Re: Addition of nocode keyword "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-10-30 05:10 -0700
    Re: Addition of nocode keyword Philipp Klaus Krause <pkk@spth.de> - 2019-10-26 18:45 +0200
  Re: Addition of nocode keyword Jakob Bohm <jb-usenet@wisemo.com.invalid> - 2019-10-28 10:42 +0100
    Re: Addition of nocode keyword "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-10-28 18:13 -0700
      Re: Addition of nocode keyword David Spencer <spencer@panix.com> - 2019-10-29 02:55 +0000
        Re: Addition of nocode keyword "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-10-29 07:58 -0400
          Re: Addition of nocode keyword David Spencer <spencer@panix.com> - 2019-10-29 20:21 +0000
            Re: Addition of nocode keyword "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-10-29 13:31 -0700
              Re: Addition of nocode keyword jameskuyper@alumni.caltech.edu - 2019-10-29 14:47 -0700
                Re: Addition of nocode keyword "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-10-29 19:36 -0400
                Re: Addition of nocode keyword Richard Damon <Richard@Damon-Family.org> - 2019-10-29 22:13 -0400
                Re: Addition of nocode keyword "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-10-30 05:03 -0700
                Re: Addition of nocode keyword David Brown <david.brown@hesbynett.no> - 2019-10-30 09:48 +0100
                Re: Addition of nocode keyword "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-10-30 05:13 -0700
                Re: Addition of nocode keyword Keith Thompson <kst-u@mib.org> - 2019-10-30 08:40 -0700
                Re: Addition of nocode keyword "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-10-30 09:44 -0700
                Re: Addition of nocode keyword David Brown <david.brown@hesbynett.no> - 2019-10-30 18:30 +0100
                Re: Addition of nocode keyword jameskuyper@alumni.caltech.edu - 2019-10-30 08:12 -0700
                Re: Addition of nocode keyword Nick Bowler <nbowler@draconx.ca> - 2019-10-30 16:47 +0000
                Re: Addition of nocode keyword James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-10-30 13:30 -0400
                Re: Addition of nocode keyword David Brown <david.brown@hesbynett.no> - 2019-10-30 18:37 +0100
                Re: Addition of nocode keyword Nick Bowler <nbowler@draconx.ca> - 2019-10-30 18:34 +0000
                Re: Addition of nocode keyword Keith Thompson <kst-u@mib.org> - 2019-10-31 10:14 -0700
                Re: Addition of nocode keyword "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-10-30 21:29 -0400
                Re: Addition of nocode keyword jameskuyper@alumni.caltech.edu - 2019-10-31 08:37 -0700
                Re: Addition of nocode keyword "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-10-31 09:38 -0700
                Re: Addition of nocode keyword David Brown <david.brown@hesbynett.no> - 2019-10-31 19:50 +0100
                Re: Addition of nocode keyword Philipp Klaus Krause <pkk@spth.de> - 2020-08-04 11:18 +0200
                Re: Addition of nocode keyword "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-11-01 07:20 -0700
              Re: Addition of nocode keyword David Spencer <spencer@panix.com> - 2019-10-29 23:46 +0000
                Re: Addition of nocode keyword "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-10-29 21:41 -0400
              Re: Addition of nocode keyword guinness.tony@gmail.com - 2019-10-30 04:36 -0700
                Re: Addition of nocode keyword Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-31 00:19 +0000
    Re: Addition of nocode keyword David Brown <david.brown@hesbynett.no> - 2019-10-29 14:32 +0100
      Re: Addition of nocode keyword Jakob Bohm <jb-usenet@wisemo.com.invalid> - 2019-10-29 17:41 +0100
        Re: Addition of nocode keyword David Brown <david.brown@hesbynett.no> - 2019-10-29 23:24 +0100

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