Re: another C-like language? was Compilers :)

From	Kaz Kylheku <864-117-4973@kylheku.com>
Newsgroups	comp.compilers
Subject	Re: another C-like language? was Compilers :)
Date	2023-01-14 19:07 +0000
Organization	A noiseless patient Spider
Message-ID	<23-01-057@comp.compilers> (permalink)
References	(2 earlier) <23-01-003@comp.compilers> <23-01-008@comp.compilers> <23-01-016@comp.compilers> <23-01-029@comp.compilers> <23-01-052@comp.compilers>

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On 2023-01-13, Luke A. Guest <laguest@archeia.com> wrote:
> On 09/01/2023 17:41, Kaz Kylheku wrote:
>> On 2023-01-06, David Brown <david.brown@hesbynett.no> wrote:
>>> don't want to go through them all, but I agree with you that the style
>>> of "all your declarations at the start of the function" is long
>>> outdated, and often - but not universally - considered a bad idea.)
>>
>> Declarations have never been required to be at the top of a function in
>> C, because they can be in any compound statement block. I think
>> that goes all the way back to the B language. [Nope, see the next message. -John]
>
> When I learnt C, you had to define your variables at the top of the
> block {} whether that's a function or a block within the function somewhere.

Well yes; that is the situation in ISO C 90. ISO C 99 introduced mixed
declarations and statements. Or, perhaps we should say, the C++ dialect
introduced this (and standardized it first, in 1998).

>> The "Variables at the top" meme may be something coming from Pascal.
>
> Nope. Algol. C is an Algol derived language.
>
>> IIRC, in Pascal, compound statements aren't full blocks; they cannot
>> have VAR declarations.
>>
>> When programmers abandoned Pascal in the 1980s, they carried over this
>> habit into C.
>
> Nope, this was defined in the C spec and the K&R book. Apparently this
> has been relaxed recently-ish and now variables can be defined anywhere.

The discussion is about whether variables must be declared at the top of
the entire function, even if it has nested compound statements where
some of them could be declared.

The top-of-function restriction exists in Pascal; compound statements
do not have VAR section.

--
TXR Programming Language: http://nongnu.org/txr
Cygnal: Cygwin Native Application Library: http://kylheku.com/cygnal
Mastodon: @Kazinator@mstdn.ca
[Algol60 allowed declarations at the start of every block, so I think
it was one of the things Pascal left out to make it easier to compile.
It does make one-pass compiling with tiny memory easier.  These days,
that's irrelevant. -John]

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Compilers :) "Tristan B. Velloza Kildaire" <deavmi@redxen.eu> - 2023-01-02 12:28 +0200
  Re: Compilers :) Spiros Bousbouras <spibou@gmail.com> - 2023-01-02 20:52 +0000
    Re: another C-like language? was Compilers :) Steve Limb <stephenjohnlimb@gmail.com> - 2023-01-03 16:24 +0000
      Re: another C-like language? was Compilers :) gah4 <gah4@u.washington.edu> - 2023-01-03 12:52 -0800
        Re: another C-like language? was Compilers :) arnold@skeeve.com (Aharon Robbins) - 2023-01-04 17:12 +0000
          Re: another C-like language? was Compilers :) gah4 <gah4@u.washington.edu> - 2023-01-04 12:39 -0800
      Re: another C-like language? was Compilers :) "marb...@yahoo.co.uk" <marblypup@yahoo.co.uk> - 2023-01-05 06:27 -0800
        Re: another C-like language? was Compilers :) gah4 <gah4@u.washington.edu> - 2023-01-05 16:26 -0800
        Re: another C-like language? was Compilers :) David Brown <david.brown@hesbynett.no> - 2023-01-06 15:39 +0100
          Re: another C-like language? was Compilers :) Kaz Kylheku <864-117-4973@kylheku.com> - 2023-01-09 17:41 +0000
            Re: another C-like language? was Compilers :) David Brown <david.brown@hesbynett.no> - 2023-01-10 17:48 +0100
              Re: another C-like language? was Compilers :) gah4 <gah4@u.washington.edu> - 2023-01-10 15:13 -0800
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                Re: back in the 60s, another C-like language? was Compilers :) gah4 <gah4@u.washington.edu> - 2023-01-11 16:38 -0800
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            Re: another C-like language? was Compilers :) "Luke A. Guest" <laguest@archeia.com> - 2023-01-13 18:25 +0000
              Re: another C-like language? was Compilers :) George Neuner <gneuner2@comcast.net> - 2023-01-13 17:20 -0500
              Re: another C-like language? was Compilers :) Kaz Kylheku <864-117-4973@kylheku.com> - 2023-01-14 19:07 +0000
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    Re: Compilers :) "Tristan B. Velloza Kildaire" <deavmi@redxen.eu> - 2023-01-13 13:41 +0200
  Re: Compilers :) Hans-Peter Diettrich <DrDiettrich1@netscape.net> - 2023-01-05 01:12 +0100
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        Re: C and Java, was Compilers :) gah4 <gah4@u.washington.edu> - 2023-01-13 12:39 -0800
          Re: C and Java, was Compilers :) dave_thompson_2@comcast.net - 2023-01-28 10:37 -0500
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