Re: simple session question

From	Jerry Stuckle <jstucklex@attglobal.net>
Newsgroups	comp.lang.php
Subject	Re: simple session question
Date	2011-10-22 23:03 -0400
Organization	A noiseless patient Spider
Message-ID	<j80057$5j7$1@dont-email.me> (permalink)
References	(5 earlier) <j7st09$al6$1@news.albasani.net> <j7str1$4k0$1@dont-email.me> <j7uh5i$rvt$2@news.albasani.net> <j7vc0i$pnr$1@dont-email.me> <j7vm55$2q5$1@news.albasani.net>

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On 10/22/2011 8:12 PM, Thomas Mlynarczyk wrote:
> Richard Damon schrieb:
>
>> I suspect that there is a difference between the execution model of
>> C/C++ and PHP here, do in part to the fact that C/C++ is (normally) a
>> compiled language with the goal of allowing the compiler to generate
>> as efficient of code as possible, while PHP is designed as a
>> interpreted language.
>
> Hm. But PHP is written in C, so I would assume it to just follow C here.
>
>> x = x; /* perform the = */
>> x = x+1; /* perform the ++ */
>
> That could be further optimized by dropping the x = x. But here the
> assignment seems to have a higher precedence than the increment.
>
>> temp = x;
>> x = x+1;
>> ... do what ever with temp
>>
>> Which being an interpreted language makes some sense, why put off
>> doing something, and recording somewhere that you need to do it, when
>> you can do it now, the possible savings that C might have been able to
>> make, get swamped by the other overhead in PHP.
>
> Now I wonder why x = x++ is undefined in C. If it was defined to be a no
> op as it behaves in PHP, then it could be optimized away completely.
>
> Greetings,
> Thomas
>

Because it's not a noop.  The language only defined the order of 
operator evaluation - not operand evaluation.  Some C compilers will 
return 0, others will return 1.

The problem here is you are setting the value in the operand ($!foo) 
twice in the same expression.  Results of such operations is always 
undefined in C.

-- 
==================
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
jstucklex@attglobal.net
==================

Thread

simple session question cerr <ron.eggler@gmail.com> - 2011-10-21 10:44 -0700
  Re: simple session question Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2011-10-21 20:19 +0200
    Re: simple session question Jonathan Stein <jstein@image.dk> - 2011-10-21 20:51 +0200
      Re: simple session question Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2011-10-21 22:00 +0200
        Re: simple session question Jerry Stuckle <jstucklex@attglobal.net> - 2011-10-21 16:14 -0400
          Re: simple session question Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2011-10-22 00:50 +0200
            Re: simple session question Jerry Stuckle <jstucklex@attglobal.net> - 2011-10-21 19:05 -0400
              Re: simple session question Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2011-10-22 15:40 +0200
                Re: simple session question Richard Damon <news.x.richarddamon@xoxy.net> - 2011-10-22 17:19 -0400
                Re: simple session question The Natural Philosopher <tnp@invalid.invalid> - 2011-10-22 22:56 +0100
                Re: simple session question Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2011-10-23 00:35 +0200
                Re: simple session question Tim Streater <timstreater@greenbee.net> - 2011-10-22 23:43 +0100
                Re: simple session question Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2011-10-23 01:56 +0200
                Re: simple session question Richard Damon <news.x.richarddamon@xoxy.net> - 2011-10-22 19:29 -0400
                Re: simple session question Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2011-10-23 01:54 +0200
                Re: simple session question Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2011-10-23 02:12 +0200
                Re: simple session question Richard Damon <news.x.richarddamon@xoxy.net> - 2011-10-22 21:13 -0400
                Re: simple session question The Natural Philosopher <tnp@invalid.invalid> - 2011-10-23 08:44 +0100
                Re: simple session question Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2011-10-23 17:31 +0200
                Re: simple session question The Natural Philosopher <tnp@invalid.invalid> - 2011-10-23 17:18 +0100
                Re: simple session question Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2011-10-23 19:14 +0200
                Re: simple session question The Natural Philosopher <tnp@invalid.invalid> - 2011-10-23 18:16 +0100
                Re: simple session question Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2011-10-23 19:00 +0200
                Re: simple session question Richard Damon <news.x.richarddamon@xoxy.net> - 2011-10-23 15:28 -0400
                Re: simple session question Jerry Stuckle <jstucklex@attglobal.net> - 2011-10-22 23:03 -0400
                Re: simple session question Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2011-10-23 19:06 +0200
                Re: simple session question Jerry Stuckle <jstucklex@attglobal.net> - 2011-10-23 14:35 -0400
            Re: simple session question The Natural Philosopher <tnp@invalid.invalid> - 2011-10-22 00:32 +0100
              Re: simple session question Luuk <Luuk@invalid.lan> - 2011-10-22 12:01 +0200
                Re: simple session question The Natural Philosopher <tnp@invalid.invalid> - 2011-10-22 15:27 +0100
                Re: simple session question The Natural Philosopher <tnp@invalid.invalid> - 2011-10-22 15:37 +0100
                Re: simple session question Luuk <Luuk@invalid.lan> - 2011-10-22 17:08 +0200
                OT: and even in Dart .........Re: simple session question Luuk <Luuk@invalid.lan> - 2011-10-22 17:17 +0200
                Re: OT: and even in Dart .........Re: simple session question The Natural Philosopher <tnp@invalid.invalid> - 2011-10-22 16:54 +0100
                Re: OT: and even in Dart .........Re: simple session question Luuk <Luuk@invalid.lan> - 2011-10-22 18:47 +0200
                Re: OT: and even in Dart .........Re: simple session question Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2011-10-22 19:34 +0200
                Re: OT: and even in Dart .........Re: simple session question Norman Peelman <npeelmandog@cfl.rr.com> - 2011-10-22 16:08 -0400
                Re: OT: and even in Dart .........Re: simple session question Jerry Stuckle <jstucklex@attglobal.net> - 2011-10-22 16:28 -0400
                Re: OT: and even in Dart .........Re: simple session question Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2011-10-23 01:39 +0200
                Re: OT: and even in Dart .........Re: simple session question Norman Peelman <npeelmandog@cfl.rr.com> - 2011-10-22 22:40 -0400
                Re: OT: and even in Dart .........Re: simple session question Jerry Stuckle <jstucklex@attglobal.net> - 2011-10-22 23:05 -0400
                Re: OT: and even in Dart .........Re: simple session question The Natural Philosopher <tnp@invalid.invalid> - 2011-10-22 22:52 +0100
                Re: OT: and even in Dart .........Re: simple session question Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2011-10-23 01:25 +0200
                Re: OT: and even in Dart .........Re: simple session question The Natural Philosopher <tnp@invalid.invalid> - 2011-10-23 08:41 +0100
                Re: OT: and even in Dart .........Re: simple session question Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2011-10-23 00:56 +0200
                Re: OT: and even in Dart .........Re: simple session question Norman Peelman <npeelmandog@cfl.rr.com> - 2011-10-22 22:52 -0400
                Re: OT: and even in Dart .........Re: simple session question Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2011-10-23 17:12 +0200
                Re: OT: and even in Dart .........Re: simple session question Tim Streater <timstreater@greenbee.net> - 2011-10-23 09:39 +0100
                Re: OT: and even in Dart .........Re: simple session question The Natural Philosopher <tnp@invalid.invalid> - 2011-10-23 09:40 +0100
                Re: OT: and even in Dart .........Re: simple session question Tim Streater <timstreater@greenbee.net> - 2011-10-23 09:43 +0100
                Re: OT: and even in Dart .........Re: simple session question "Peter H. Coffin" <hellsop@ninehells.com> - 2011-11-05 15:04 -0500
                Re: OT: and even in Dart .........Re: simple session question The Natural Philosopher <tnp@invalid.invalid> - 2011-10-22 22:47 +0100
                Re: OT: and even in Dart .........Re: simple session question Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2011-10-23 01:22 +0200
                Re: OT: and even in Dart .........Re: simple session question The Natural Philosopher <tnp@invalid.invalid> - 2011-10-23 08:40 +0100
                Re: OT: and even in Dart .........Re: simple session question Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2011-10-23 17:04 +0200
                Re: OT: and even in Dart .........Re: simple session question "Peter H. Coffin" <hellsop@ninehells.com> - 2011-11-05 15:00 -0500
              Re: simple session question Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2011-10-22 15:39 +0200
    Re: simple session question cerr <ron.eggler@gmail.com> - 2011-10-21 14:43 -0700
      Re: simple session question Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2011-10-22 00:47 +0200
      Re: simple session question Jerry Stuckle <jstucklex@attglobal.net> - 2011-10-21 19:06 -0400
    Re: simple session question cerr <ron.eggler@gmail.com> - 2011-10-21 14:17 -0700
      Re: simple session question Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2011-10-22 15:50 +0200
    Re: simple session question Denis McMahon <denismfmcmahon@gmail.com> - 2011-10-23 15:47 +0000

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