Hi,

is this result defined by the standard?

I'm just in a small "fight" with some workmates on this topic. So an
answer from more involved people could .

Regards,
Christian

Christian Johannes Charbula wrote:
> is this result defined by the standard?

No. The second statement contains the expression in which the rules
are broken. See the Standard, [expr]/4.

> I'm just in a small "fight" with some workmates on this topic. So an
> answer from more involved people could .

Never fight your workmates. It's detrimental to your career.

V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask

Christian Johannes Charbula wrote:
> ...
> is this result defined by the standard?
> ...

It depends on what 'x' is.

If this is an object of user-defined type (a class), manipulated by user-defined
operators, constructors, conversion functions etc., then the result might be
perfectly defined. Although there's no way to say what the result of 'x == 4' is
without seeing the actual definitions.

Otherwise (for 'x' of type 'int', for example), the expression with all those
'+'s produces undefined behavior.

--
Best regards,
Andrey Tarasevich

On 2008-02-22 11:10:50 -0500, Andrey Tarasevich
<andreytarasevich@hotmail.com> said:

>
> If this is an object of user-defined type (a class), manipulated by
> user-defined operators, constructors, conversion functions etc., then
> the result might be perfectly defined.

In that case, it's unspecified. The two increment calls aren't ordered.

A more important question, though, is "who cares?" Is it really
worhwhile spending time talking about the hypothetical meaning of an
expression that should never appear in real-world code? Even under
Java's rules, where the result is well defined, the code is abominable.

--
Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The
Standard C++ Library Extensions: a Tutorial and Reference
(www.petebecker.com/tr1book)

Pete Becker schrieb:

> A more important question, though, is "who cares?" Is it really
> worhwhile spending time talking about the hypothetical meaning of an
> expression that should never appear in real-world code? Even under
> Java's rules, where the result is well defined, the code is abominable.

Exactly, I fully second that. I do not understand at all why this exact
question comes up in this group (and in comp.lang.c, too, BTW) every few
days. Kind of annoying. You should think people have more important
problems.

Regards,
Johannes

--
"PS: Ein Realname wäre nett. Ich selbst nutze nur keinen, weil mich die
meisten hier bereits mit Namen kennen." -- Markus Gronotte aka Makus /
Kosst Amojan / maqqusz / Mr. G / Ferdinand Simpson / Quartillia
Rosenberg in dse <45608268$0$5719$9b4e6d93@newsspool3.arcor-online.net>

Johannes Bauer wrote:
> Pete Becker schrieb:
>
>> A more important question, though, is "who cares?" Is it really
>> worhwhile spending time talking about the hypothetical meaning of an
>> expression that should never appear in real-world code? Even under
>> Java's rules, where the result is well defined, the code is
>> abominable.
>
> Exactly, I fully second that. I do not understand at all why this
> exact question comes up in this group (and in comp.lang.c, too, BTW)
> every few days. Kind of annoying. You should think people have more
> important problems.

Aw, those grown-ups and their "more important problems"! When
will they understand? <g>

V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask

Pete Becker wrote:
>> ...
>> If this is an object of user-defined type (a class), manipulated by
>> user-defined operators, constructors, conversion functions etc., then
>> the result might be perfectly defined.
>
> In that case, it's unspecified. The two increment calls aren't ordered.
> ...

Yes, but the original question was not about the "behavior", but about
the "result". While the OP didn't specify what exactly he meant by
"result" (probably the result of 'x == 4' expression), for many natural
interpretations of the term it is possible to come up with operator
definitions, which will produce a well defined "result" even though the
overall "behavior" is not specified.

> A more important question, though, is "who cares?"

Apparently the OP and his workmates do. Moreover, the only people who
shouldn't care are the people who are already past that stage in their
learning process. That's definitely not everybody.

> Is it really worhwhile
> spending time talking about the hypothetical meaning of an expression
> that should never appear in real-world code?

True, but I don't see the connection. I have no reason to believe the
expressions in the subject line were taken from the real-world code, or
that anyone actually intended to use them in the real-world code.

--
Best regards,
Andrey Tarasevich

Victor Bazarov schrieb:

>> Exactly, I fully second that. I do not understand at all why this
>> exact question comes up in this group (and in comp.lang.c, too, BTW)
>> every few days. Kind of annoying. You should think people have more
>> important problems.
>
> Aw, those grown-ups and their "more important problems"! When
> will they understand? <g>

No, no, that's not how I meant it and from the grin I take it you
undertood me correctly. However, I believe that there are *dozens* of
really interesting, complex, real-world problems C++ provides - yet some
people get hung with totally arfificial problems which always boils down
to some definition in the standard - that's pretty boring :-)

Regards,
Johannes

--
"PS: Ein Realname wäre nett. Ich selbst nutze nur keinen, weil mich die
meisten hier bereits mit Namen kennen." -- Markus Gronotte aka Makus /
Kosst Amojan / maqqusz / Mr. G / Ferdinand Simpson / Quartillia
Rosenberg in dse <45608268$0$5719$9b4e6d93@newsspool3.arcor-online.net>

Christian Johannes Charbula wrote:
> is this result defined by the standard?

What result?

It's customary to write a complete question in the body of your post.
The subject line is only a short introduction to the contents of your
post, not the contents themselves. The post should be understandable
even without the subject line.

On Feb 22, 6:28 pm, Andrey Tarasevich <andreytarasev...@hotmail.com>
wrote:
> Pete Becker wrote:
> >> ...
> >> If this is an object of user-defined type (a class), manipulated by
> >> user-defined operators, constructors, conversion functions etc., then
> >> the result might be perfectly defined.

> > In that case, it's unspecified. The two increment calls aren't ordered.
> > ...

> Yes, but the original question was not about the "behavior", but about
> the "result". While the OP didn't specify what exactly he meant by
> "result" (probably the result of 'x == 4' expression), for many natural
> interpretations of the term it is possible to come up with operator
> definitions, which will produce a well defined "result" even though the
> overall "behavior" is not specified.

It's possible, but anyone who overloads the given operators with
definitions so that such a result is guaranteed should be hung
and shot. With any reasonable overloading of the operators (for
a user defined type for which such operators would make sense),
the result is unspecified.

--
James Kanze (GABI Software) email:james.kanze@gmail.com
Conseils en informatique orientée objet/
Beratung in objektorientierter Datenverarbeitung
9 place Sémard, 78210 St.-Cyr-l'École, France, +33 (0)1 30 23 00 34

James Kanze wrote:
> ...
>> Yes, but the original question was not about the "behavior", but about
>> the "result". While the OP didn't specify what exactly he meant by
>> "result" (probably the result of 'x == 4' expression), for many natural
>> interpretations of the term it is possible to come up with operator
>> definitions, which will produce a well defined "result" even though the
>> overall "behavior" is not specified.
>
> It's possible,

That's exactly what I said. It is possible.

> but anyone who overloads the given operators with
> definitions so that such a result is guaranteed should be hung
> and shot.

Considering that this discussion is centered around what essentially is
a basic C++ _puzzle_, not a piece of real-life code, the above statement
is utterly irrelevant.

> With any reasonable overloading of the operators (for
> a user defined type for which such operators would make sense),
> the result is unspecified.

This statement is based on some undefinable ideas of what "reasonable".
I'm pretty sure one can come up with a "reasonable" overload with
perfectly specified results, although I don't see the point.

--
Best regards,
Andrey Tarasevich

On 2008-02-22 12:24:11 -0500, Johannes Bauer <dfnsonfsduifb@gmx.de> said:

> Pete Becker schrieb:
>
>> A more important question, though, is "who cares?" Is it really
>> worhwhile spending time talking about the hypothetical meaning of an
>> expression that should never appear in real-world code? Even under
>> Java's rules, where the result is well defined, the code is abominable.
>
> Exactly, I fully second that. I do not understand at all why this exact
> question comes up in this group (and in comp.lang.c, too, BTW) every few
> days. Kind of annoying. You should think people have more important
> problems.

It's called knowing your tools well. If you just don't know the
answer, then just say so or better yet just be quiet.

With a tool like C++ where you can write syntactically correct code but
with undefined behavior, it's good to know when you could be writing
such code or be reading such code from another programmer. And that is
exact what the OP asked: Is this code well-defined in C++?

Furthermore, the OP did not say this is production code. He did not
ask if this code is abominable or not. It is just an inquisition about
the rules of C++. So why shouldn't this question be raised in this
forum? Which forum should this post go where it won't be annoying?

--

// kira

On Feb 22, 5:12 pm, Kira Yamato <kira...@earthlink.net> wrote:
> On 2008-02-22 12:24:11 -0500, Johannes Bauer <dfnsonfsdu...@gmx.de> said:
> > Pete Becker schrieb:
> >> A more important question, though, is "who cares?" Is it really
> >> worhwhile spending time talking about the hypothetical meaning of an
> >> expression that should never appear in real-world code? Even under
> >> Java's rules, where the result is well defined, the code is abominable.
>
> > Exactly, I fully second that. I do not understand at all why this exact
> > question comes up in this group (and in comp.lang.c, too, BTW) every few
> > days. Kind of annoying. You should think people have more important
> > problems.
>
> It's called knowing your tools well. If you just don't know the
> answer, then just say so or better yet just be quiet.

Exactly. And not only that, but these kinds of questions (aside from
being just plain interesting to some people, like me) can stem from
perfectly reasonable, real-world situations. Perhaps you come across a
bug in your code and narrow it down to some weird C++ problem; you
construct a minimal example just as you are supposed to, and you come
here and ask about it without giving background context. That's
another good reason for posting those kinds of questions here. It's
*exactly* the kind of topic that this newsgroup exists for.

On 2008-02-22 17:12:35 -0500, Kira Yamato <kirakun@earthlink.net> said:

> On 2008-02-22 12:24:11 -0500, Johannes Bauer <dfnsonfsduifb@gmx.de> said:
>
>> Pete Becker schrieb:
>>
>>> A more important question, though, is "who cares?" Is it really
>>> worhwhile spending time talking about the hypothetical meaning of an
>>> expression that should never appear in real-world code? Even under
>>> Java's rules, where the result is well defined, the code is abominable.
>>
>> Exactly, I fully second that. I do not understand at all why this exact
>> question comes up in this group (and in comp.lang.c, too, BTW) every few
>> days. Kind of annoying. You should think people have more important
>> problems.
>
> It's called knowing your tools well. If you just don't know the
> answer, then just say so or better yet just be quiet.
>

If an apprentice carpenter asks whether he can use a hammer to drive in
a screw, he should be told "No." Speculating on whether it might or
might not work in some cases doesn't him learn how to do his job.

--
Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The
Standard C++ Library Extensions: a Tutorial and Reference
(www.petebecker.com/tr1book)

On Feb 22, 7:07 pm, Pete Becker <p...@versatilecoding.com> wrote:
> If an apprentice carpenter asks whether he can use a hammer to drive in
> a screw, he should be told "No." Speculating on whether it might or
> might not work in some cases doesn't him learn how to do his job.

I completely agree. The carpenter should answer his question. The
friendly carpenter may even want to have a discussion about it. The
carpenter should *not* say "who cares?". And in any case, both
apprentice and carpenter would raise an eyebrow at and then disregard
the comment of a third guy who walked in the room out of nowhere and
said "why are you two talking about this?".

Unless you meant something else by your metaphor?

On 2008-02-22 19:07:12 -0500, Pete Becker <pete@versatilecoding.com> said:

> On 2008-02-22 17:12:35 -0500, Kira Yamato <kirakun@earthlink.net> said:
>
>> On 2008-02-22 12:24:11 -0500, Johannes Bauer <dfnsonfsduifb@gmx.de> said:
>>
>>> Pete Becker schrieb:
>>>
>>>> A more important question, though, is "who cares?" Is it really
>>>> worhwhile spending time talking about the hypothetical meaning of an
>>>> expression that should never appear in real-world code? Even under
>>>> Java's rules, where the result is well defined, the code is abominable.
>>>
>>> Exactly, I fully second that. I do not understand at all why this exact
>>> question comes up in this group (and in comp.lang.c, too, BTW) every few
>>> days. Kind of annoying. You should think people have more important
>>> problems.
>>
>> It's called knowing your tools well. If you just don't know the
>> answer, then just say so or better yet just be quiet.
>>
>
> If an apprentice carpenter asks whether he can use a hammer to drive in
> a screw, he should be told "No." Speculating on whether it might or
> might not work in some cases doesn't him learn how to do his job.

Are you kidding me? It is in the speculation of various scenarios that
we explore and learn the limits and strengths of our tools.

--

// kira

On Feb 22, 7:59 pm, Kira Yamato <kira...@earthlink.net> wrote:
> Are you kidding me? It is in the speculation of various scenarios that
> we explore and learn the limits and strengths of our tools.

No, Pete is absolutely correct. There's no point in learning more
about your tools, or having interesting discussions about them. You
should just use them without question and get the job done without
thinking. Just don't hire "Versatile Coding" to do anything for you if
you need anything more than a typing grunt.

On Feb 22, 8:07 pm, "jason.cipri...@gmail.com"
<jason.cipri...@gmail.com> wrote:
> No, Pete is absolutely correct. There's no point in learning more
> about your tools, or having interesting discussions about them. You
> should just use them without question and get the job done without
> thinking. Just don't hire "Versatile Coding" to do anything for you if
> you need anything more than a typing grunt.

Apologies, Pete. That was uncalled for -- I meant "Roundhouse
Consulting".

Pete Becker wrote:
> If an apprentice carpenter asks whether he can use a hammer to drive in
> a screw, he should be told "No." Speculating on whether it might or
> might not work in some cases doesn't him learn how to do his job.

This is only true if you the carpenter deliberately tries to restrain
the apprentice's development in order to freeze him at the "apprentice"
stage forever.

--
Best regards,
Andrey Tarasevich

On 2008-02-22 19:13:39 -0500, "jason.cipriani@gmail.com"
<jason.cipriani@gmail.com> said:

> On Feb 22, 7:07 pm, Pete Becker <p...@versatilecoding.com> wrote:
>> If an apprentice carpenter asks whether he can use a hammer to drive in
>> a screw, he should be told "No." Speculating on whether it might or
>> might not work in some cases doesn't him learn how to do his job.
>
> I completely agree. The carpenter should answer his question. The
> friendly carpenter may even want to have a discussion about it.

Interesting. You "completely agree" with something I clearly didn't say.

> The
> carpenter should *not* say "who cares?". And in any case, both
> apprentice and carpenter would raise an eyebrow at and then disregard
> the comment of a third guy who walked in the room out of nowhere and
> said "why are you two talking about this?".
>
> Unless you meant something else by your metaphor?

I meant just what I said. "No" is all that needs to be said, although
in a suitable setting it can be accompanied by laughter.

Unreadable code is unreadable code, regardless of whether its effect is
well defined.

--
Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The
Standard C++ Library Extensions: a Tutorial and Reference
(www.petebecker.com/tr1book)

On 2008-02-22 19:59:31 -0500, Kira Yamato <kirakun@earthlink.net> said:

> On 2008-02-22 19:07:12 -0500, Pete Becker <pete@versatilecoding.com> said:
>
>> On 2008-02-22 17:12:35 -0500, Kira Yamato <kirakun@earthlink.net> said:
>>
>>> On 2008-02-22 12:24:11 -0500, Johannes Bauer <dfnsonfsduifb@gmx.de> said:
>>>
>>>> Pete Becker schrieb:
>>>>
>>>>> A more important question, though, is "who cares?" Is it really
>>>>> worhwhile spending time talking about the hypothetical meaning of an
>>>>> expression that should never appear in real-world code? Even under
>>>>> Java's rules, where the result is well defined, the code is abominable.
>>>>
>>>> Exactly, I fully second that. I do not understand at all why this exact
>>>> question comes up in this group (and in comp.lang.c, too, BTW) every few
>>>> days. Kind of annoying. You should think people have more important
>>>> problems.
>>>
>>> It's called knowing your tools well. If you just don't know the
>>> answer, then just say so or better yet just be quiet.
>>>
>>
>> If an apprentice carpenter asks whether he can use a hammer to drive in
>> a screw, he should be told "No." Speculating on whether it might or
>> might not work in some cases doesn't him learn how to do his job.
>
> Are you kidding me? It is in the speculation of various scenarios that
> we explore and learn the limits and strengths of our tools.

And what strengths and weaknesses do you expect to learn from exploring
the abomination that started this discussion?

The code is unreadable, regardless of whether its meaning is well
defined. It has no reason to exist in a production environment.

--
Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The
Standard C++ Library Extensions: a Tutorial and Reference
(www.petebecker.com/tr1book)

On 2008-02-22 20:07:07 -0500, "jason.cipriani@gmail.com"
<jason.cipriani@gmail.com> said:

> On Feb 22, 7:59 pm, Kira Yamato <kira...@earthlink.net> wrote:
>> Are you kidding me? It is in the speculation of various scenarios that
>> we explore and learn the limits and strengths of our tools.
>
> No, Pete is absolutely correct. There's no point in learning more
> about your tools, or having interesting discussions about them. You
> should just use them without question and get the job done without
> thinking. Just don't hire "Versatile Coding" to do anything for you if
> you need anything more than a typing grunt.

Sigh. You haven't even labeled this subthread "OT", despite making only
a personal attack.

--
Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The
Standard C++ Library Extensions: a Tutorial and Reference
(www.petebecker.com/tr1book)

On 2008-02-22 20:09:11 -0500, "jason.cipriani@gmail.com"
<jason.cipriani@gmail.com> said:

> On Feb 22, 8:07 pm, "jason.cipri...@gmail.com"
> <jason.cipri...@gmail.com> wrote:
>> No, Pete is absolutely correct. There's no point in learning more
>> about your tools, or having interesting discussions about them. You
>> should just use them without question and get the job done without
>> thinking. Just don't hire "Versatile Coding" to do anything for you if
>> you need anything more than a typing grunt.
>
> Apologies, Pete. That was uncalled for -- I meant "Roundhouse
> Consulting".

PLONK.

--
Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The
Standard C++ Library Extensions: a Tutorial and Reference
(www.petebecker.com/tr1book)

On Feb 23, 8:24 am, Pete Becker <p...@versatilecoding.com> wrote:
> Sigh. You haven't even labeled this subthread "OT", despite making only
> a personal attack.

I noticed; Google Groups removed the [OT]. A personal attack was
pretty much the only thing to say to the asinine comments you've been
making.

On Feb 23, 8:23 am, Pete Becker <p...@versatilecoding.com> wrote:
> And what strengths and weaknesses do you expect to learn from exploring
> the abomination that started this discussion?

Pete, be honest -- what point are you arguing here? Somebody came to
comp.lang.c++ and asked a question about c++ that they were interested
in for their own curiosity. What, exactly, are you saying? That they
shouldn't have? That it was a stupid question? Great. Are you implying
that nobody should care about "silly" questions like that in C++, but
everybody *should* care that you think it's an irrelevant question? Is
that what is more important, letting everybody know that you think
those kinds of questions are stupid? Do you have a "point" that you
are trying to make beyond "I thought the poster's completely on topic
and honest question was dumb, and asking these kinds of questions
doesn't me learn about my tools therefore it should nobody
else?" Is there something that you want?