I was talking about telling the 'undefined behaviour' case; not what happens with the values exactly. I don't see a drawback in documenting an 'undefined behaviour'. It's good for people to have a torough documentation which even warns them before they're doing silly things. Note that the majority of users of PHP are non-programmers. Warning them before they shoot themselves a good thing [tm].
On Mon, Dec 23, 2002 at 08:53:41AM -0800, David Gillies wrote : > --- Markus Fischer <[EMAIL PROTECTED]> wrote: > > So shouldn't we document those special case on > > the operators > > page ? > > > > No. Any developer worth his salt knows not to do silly > things like this. It's not a 'special case'. It's just > undefined behaviour. If your code uses syntax like > this it is broken. > > As for 'why', in the implementation sense, this > happens, I would imagine that the reference, by > increasing the refcount of the variable, moves > evaluation of the postincrement operator to a > different sequence point. Just don't do it. Modifying > the value of a variable twice between sequence points > yields UNDEFINED BEHAVIOUR. That mean anything at all > can happen, up to and including your hard drive being > reformatted and rude emails being sent to your boss. > > You do NOT neeed to know the details. As K&R points > out: "if you don't know *how* [assorted weird tricks] > are done on various machines, that innocence may help > to protect you." > > Best Wishes > > David Gillies > San Jose > Costa Rica > > > > On Sun, Dec 22, 2002 at 10:26:08AM +0200, Andrey > > Hristov wrote : > > > oukei, stopping to ask anymore :)) > > > > > > Andrey > > > > > > > > > ----- Original Message ----- > > > From: "Andi Gutmans" <[EMAIL PROTECTED]> > > > To: "Andrey Hristov" <[EMAIL PROTECTED]>; > > <[EMAIL PROTECTED]> > > > Sent: Saturday, December 21, 2002 7:20 PM > > > Subject: Re: [PHP-DEV] Interesting result > > > > > > > > > > Again, as it is undefined in PHP the question > > "Why" in itself is wrong :) > > > > > > > > Andi > > > > > > > > At 04:43 PM 12/21/2002 +0200, Andrey Hristov > > wrote: > > > > > > > > >----- Original Message ----- > > > > >From: "Andi Gutmans" <[EMAIL PROTECTED]> > > > > >To: "Andrey Hristov" <[EMAIL PROTECTED]>; > > <[EMAIL PROTECTED]> > > > > >Sent: Saturday, December 21, 2002 4:17 PM > > > > >Subject: Re: [PHP-DEV] Interesting result > > > > > > > > > > > > > > > > It doesn't matter because the behavior here > > is undefined just like in > > > C. > > > > > > You can't use a variable and it's post/pre > > increment value in the same > > > > > > expression. > > > > > > > > > > > > > > > >Two years ago I've been told by a professort > > that a+++a+++a depends on > > > the > > > > >language and the compiler. Yesterday i found > > this page : > > > > > > >http://www.blueshoes.org/en/developer/syntax_exam/ > > > > >If a=1 -> > > > > >Java : 6 > > > > >PHP : 6 > > > > >gcc 2.95 : 3 > > > > > > > > > >I know that is "on the edge" and I will never > > use it in real script by I > > > was > > > > >curious why the > > > > >reference change the result. > > > > > > > > > >Best wishes, > > > > >Andrey > > > > > > > > > > > > > > > > > At 03:26 PM 12/21/2002 +0200, Andrey Hristov > > wrote: > > > > > > > Hi, > > > > > > >i got an interesting case : > > > > > > > > > > > > > ><?php > > > > > > >$a = 1; > > > > > > >var_dump($a + $a++); > > > > > > > > > > > > > > > > > > > > >$a = 1; > > > > > > >$x = &$a; > > > > > > >var_dump($a + $a++); > > > > > > > > > > > > > >?> > > > > > > >Result > > > > > > >int(2) > > > > > > >int(3) > > > > > > > > > > > > > > > > > > > > -- > > > PHP Development Mailing List <http://www.php.net/> > > > To unsubscribe, visit: > > http://www.php.net/unsub.php > > > > -- > > PHP Development Mailing List <http://www.php.net/> > > To unsubscribe, visit: http://www.php.net/unsub.php > > > > > __________________________________________________ > Do you Yahoo!? > Yahoo! Mail Plus - Powerful. Affordable. Sign up now. > http://mailplus.yahoo.com -- PHP Development Mailing List <http://www.php.net/> To unsubscribe, visit: http://www.php.net/unsub.php
