From: kaz@vision.crest.nt.com (Kaz Kylheku)
Subject: Re: Not intended for use in medical,
Date: 1997/05/06
Date: 1997-05-06T00:00:00+00:00 [thread overview]
Message-ID: <5kmek2$9re@bcrkh13.bnr.ca> (raw)
In-Reply-To: 5kl9qc$g4d@bcrkh13.bnr.ca
In article <5kl9qc$g4d@bcrkh13.bnr.ca>,
Kaz Kylheku <kaz@vision.crest.nt.com> wrote:
>In article <dewar.862775250@merv>, Robert Dewar <dewar@merv.cs.nyu.edu> wrote:
>>Kaz said
>>
>><<Sorry about this C intrusion into comp.lang.ada. I didn't intend that
>> example to spark a discussion about C semantics, but just to clear up,
>> the && operator in C has sequencing properties. Its left constituent
>> must not only be evaluated before its right, but its side effects must
>> also be settled before the left side is evaluated. Hence x++ && x++ is
>> perfectly well defined. The program I was writing depended on this crucial
>> sequencing property.>>
>>
>> Yes, legal, but horrible. A good reminder of why Ada does NOT have
>> the ++ operator built in :-)
By the way, the x++ is just another way of writing the assignment expression x
+= 1, or x = x + 1 (the latter case evaluates x twice, of course). The real
``evil'' perhaps is that in C an assignment is an expression rather than a
statement, so that you can decorate a complex expression with assignments all
over the place.
Note that this is one of the areas of C which C++ _worsens_ significantly.
In C++, the result of an assignment expression is not only an expression
itself, but it is also an _lvalue_. Talk about lunacy.
With one stroke, the C++ ``designers'' introduce a whole new batch of nonsense,
such as
(i = x) = y;
which must be rejected by any conforming C implementation as constraint
violation.
What's the final value of i? Is it x? Or is it y?
My friend, do not waste your time: the behavior's undefined.
Better C indeed! :)
next prev parent reply other threads:[~1997-05-06 0:00 UTC|newest]
Thread overview: 127+ messages / expand[flat|nested] mbox.gz Atom feed top
1997-04-23 0:00 Not intended for use in medical, Robert C. Leif, Ph.D.
1997-04-24 0:00 ` J. Florio
1997-04-25 0:00 ` Ken Garlington
1997-04-25 0:00 ` Kevin Cline
1997-04-25 0:00 ` Robert Dewar
1997-04-28 0:00 ` John Apa
1997-04-28 0:00 ` Robert Dewar
1997-04-29 0:00 ` Kaz Kylheku
1997-04-30 0:00 ` John Apa
[not found] ` <3367CE1E.5ED1@die_spammer.dasd.honeywell.com>
1997-05-01 0:00 ` Kaz Kylheku
1997-05-03 0:00 ` Simon Wright
1997-05-04 0:00 ` Kaz Kylheku
1997-05-04 0:00 ` Robert Dewar
1997-05-04 0:00 ` Richard Kenner
1997-05-05 0:00 ` Kaz Kylheku
1997-05-06 0:00 ` Kaz Kylheku [this message]
1997-05-06 0:00 ` Robert A Duff
1997-05-07 0:00 ` Kaz Kylheku
1997-05-08 0:00 ` Robert A Duff
1997-05-07 0:00 ` Robert Dewar
1997-05-08 0:00 ` John G. Volan
1997-05-10 0:00 ` Robert Dewar
1997-05-10 0:00 ` John G. Volan
1997-05-11 0:00 ` Robert Dewar
1997-05-11 0:00 ` John G. Volan
1997-05-11 0:00 ` Robert A Duff
1997-05-12 0:00 ` John G. Volan
1997-05-12 0:00 ` Robert Dewar
1997-05-11 0:00 ` John G. Volan
1997-05-11 0:00 ` Robert Dewar
1997-05-12 0:00 ` John G. Volan
1997-05-12 0:00 ` Robert Dewar
1997-05-17 0:00 ` Robert I. Eachus
[not found] ` <dewar.863877808@merv>
1997-05-17 0:00 ` Robert Dewar
1997-05-17 0:00 ` Jon S Anthony
1997-05-21 0:00 ` Syntax for tagged record types (was Re: Not intended for use in medical,) Ben Brosgol
1997-05-20 0:00 ` Matthew Heaney
1997-05-21 0:00 ` Syntax for tagged record types and class types Mats Weber
1997-05-21 0:00 ` Matthew Heaney
1997-05-22 0:00 ` Mats Weber
1997-05-27 0:00 ` Tucker Taft
1997-05-30 0:00 ` Mats.Weber
1997-05-22 0:00 ` Samuel A. Mize
1997-05-22 0:00 ` Samuel A. Mize
1997-05-23 0:00 ` Mats Weber
1997-05-21 0:00 ` Syntax for tagged record types (was Re: Not intended for use in medical,) Jon S Anthony
1997-05-21 0:00 ` Matthew Heaney
1997-05-22 0:00 ` Robert I. Eachus
1997-05-25 0:00 ` Matthew Heaney
1997-05-28 0:00 ` Robert I. Eachus
1997-05-23 0:00 ` Jon S Anthony
1997-05-23 0:00 ` Simon Wright
1997-05-23 0:00 ` Matthew Heaney
1997-05-25 0:00 ` Jon S Anthony
1997-05-28 0:00 ` Syntax for tagged record types (was Re David Kristola
[not found] ` <mheaney-ya023680002005972314260001@news.ni.net <mheaney-ya023680002105972302430001@news.ni.net>
1997-05-22 0:00 ` Syntax for tagged record types (was Re: Not intended for use in medical,) Robert A Duff
1997-05-22 0:00 ` John G. Volan
1997-05-23 0:00 ` Matthew Heaney
1997-05-23 0:00 ` Jon S Anthony
1997-05-23 0:00 ` Matthew Heaney
1997-05-25 0:00 ` Robert Dewar
1997-05-25 0:00 ` Jon S Anthony
1997-05-27 0:00 ` Ray Blaak
1997-05-23 0:00 ` John G. Volan
1997-05-24 0:00 ` Robert A Duff
1997-05-24 0:00 ` Matthew Heaney
1997-05-28 0:00 ` Robert I. Eachus
1997-05-25 0:00 ` Jon S Anthony
1997-05-23 0:00 ` Jon S Anthony
1997-05-12 0:00 ` Not intended for use in medical, John G. Volan
1997-05-12 0:00 ` Language Design Mistakes (was "not intended...") W. Wesley Groleau (Wes)
1997-05-13 0:00 ` Robert Dewar
1997-05-13 0:00 ` W. Wesley Groleau (Wes)
1997-05-13 0:00 ` Robert A Duff
1997-05-14 0:00 ` Robert Dewar
1997-05-08 0:00 ` Not intended for use in medical, Robert A Duff
1997-05-09 0:00 ` Robert I. Eachus
1997-05-11 0:00 ` Robert Dewar
1997-05-11 0:00 ` Matthew Heaney
1997-05-12 0:00 ` Robert Dewar
1997-05-12 0:00 ` Matthew Heaney
1997-05-13 0:00 ` Jon S Anthony
1997-05-13 0:00 ` Matthew Heaney
1997-05-14 0:00 ` Robert Dewar
1997-05-14 0:00 ` Robert Dewar
1997-05-14 0:00 ` Robert Dewar
1997-05-14 0:00 ` Nick Roberts
1997-05-14 0:00 ` Robert Dewar
1997-05-15 0:00 ` W. Wesley Groleau (Wes)
1997-05-12 0:00 ` Robert I. Eachus
1997-05-13 0:00 ` Robert Dewar
1997-05-14 0:00 ` Nick Roberts
1997-05-14 0:00 ` Robert Dewar
[not found] ` <01bc6182$30e3a7c0$LocalHost@xhv46.dial.pipex.com>
1997-05-16 0:00 ` Robert Dewar
1997-05-16 0:00 ` Robert A Duff
1997-05-16 0:00 ` Robert I. Eachus
1997-05-18 0:00 ` Nick Roberts
1997-05-18 0:00 ` Matthew Heaney
1997-05-19 0:00 ` Robert I. Eachus
1997-05-19 0:00 ` Matthew Heaney
1997-05-20 0:00 ` Nick Roberts
1997-05-20 0:00 ` Matthew Heaney
1997-05-21 0:00 ` Dale Stanbrough
1997-05-19 0:00 ` Robert A Duff
1997-05-08 0:00 ` Kaz Kylheku
1997-05-08 0:00 ` Robert Dewar
1997-05-09 0:00 ` Kaz Kylheku
1997-05-12 0:00 ` W. Wesley Groleau (Wes)
1997-05-12 0:00 ` John G. Volan
1997-05-14 0:00 ` Nick Roberts
1997-05-14 0:00 ` Robert Dewar
1997-05-14 0:00 ` Jeff Carter
[not found] ` <dewar.863632434@merv>
1997-05-15 0:00 ` Kaz Kylheku
1997-05-18 0:00 ` Robert Dewar
1997-05-15 0:00 ` Kaz Kylheku
1997-05-04 0:00 ` Richard Kenner
1997-05-04 0:00 ` Robert Dewar
1997-04-28 0:00 ` John M. Mills
1997-04-30 0:00 ` Larry Kilgallen
1997-05-02 0:00 ` Nick Roberts
-- strict thread matches above, loose matches on Subject: below --
1997-04-25 0:00 Robert C. Leif, Ph.D.
1997-05-12 0:00 Marin David Condic, 561.796.8997, M/S 731-93
1997-05-13 0:00 ` Robert Dewar
1997-05-14 0:00 tmoran
1997-05-14 0:00 Marin David Condic, 561.796.8997, M/S 731-93
1997-05-14 0:00 Marin David Condic, 561.796.8997, M/S 731-93
1997-05-19 0:00 Robert C. Leif, Ph.D.
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