Path: csiph.com!eternal-september.org!feeder.eternal-september.org!reader02.eternal-september.org!.POSTED!not-for-mail
From: Keith Thompson <kst-u@mib.org>
Newsgroups: comp.lang.c
Subject: Re: >< swap operator
Date: Sun, 07 Oct 2018 17:10:26 -0700
Organization: None to speak of
Lines: 33
Message-ID: <lnefd11eod.fsf@kst-u.example.com>
References: <36d546c5-b471-45fc-b87a-8ebebdc0c0b7@googlegroups.com> <878t3dpsl6.fsf@bsb.me.uk> <3f3b2fe4-5729-432c-889e-2f016b52dc45@googlegroups.com> <pp5scn$ugm$1@dont-email.me> <pp5sjp$v8g$1@dont-email.me> <IWutD.284123$cw.210820@fx39.am4> <9d5c4ae9-47ef-4da0-9b39-e7dbc96ab1be@googlegroups.com> <AXwtD.11298$PI.11041@fx25.am4> <pp75cb$3ef$1@dont-email.me> <CPMtD.50$vf.6@fx05.am4> <87va6gjile.fsf@bsb.me.uk> <UGPtD.329$p%6.29@fx26.am4> <87d0snkcs4.fsf@bsb.me.uk> <zT0uD.23929$1C7.14337@fx38.am4> <87o9c6j4fl.fsf@bsb.me.uk> <J2muD.2814$el1.2041@fx34.am4> <87pnwlhp1q.fsf@bsb.me.uk> <eoouD.1348$Do.1024@fx31.am4> <3d46f51b-bfcf-4966-8528-aa586e5e0cdb@googlegroups.com> <w5ruD.26058$1C7.3383@fx38.am4> <e44d5b48-970b-4d56-bfff-df85b608d5bf@googlegroups.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Injection-Info: reader02.eternal-september.org; posting-host="044f0ceb07b55f0a559303158e3458ae"; logging-data="21172"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX191xgU13ZK9qOCOErzbaLnP"
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux)
Cancel-Lock: sha1:RiRCIPAtmC8HaIgkWNNs/zWkJ3U= sha1:oV6VKCtmDdyoaVKycF4PSF110JA=
Xref: csiph.com comp.lang.c:136408

jameskuyper@alumni.caltech.edu writes:
> On Sunday, October 7, 2018 at 1:10:01 PM UTC-4, Bart wrote:
[...]
>> Take a working program. Find a place where a semicolon follows what 
>> could be used as an expression in an expression context. Now remove the 
>> semicolon. If it still compiles,
>
> That will never happen. There is no grammar rules that permit two
> consecutive expressions to occur with nothing in between them. The
> closest you can get is the comma operator.

There are some cases.  For example:
    a + b;
    +c;
and
    a + b;
    *c;

Of course these cases have no relevance to whatever point Bart is
failing to make.  They depend on two different operators using the
same symbol.  In both cases, the expression (part of an expression
statement) on the second line is no longer an expression after the
semicolon is removed.  (C's grammar happens to be what I think of as
"dense", meaning roughly that it's relatively easy for arbitrary
sequences of token to be syntactically valid.)

[...]

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"