Bug #78829 [Nab->Fbk]: 数字传引用计算问题

Edit report at https://bugs.php.net/bug.php?id=78829&edit=1 ID: 78829 Updated by: requinix@php.net Reported by: 1003674174 at qq dot com Summary: 数字传引用计算问题 -Status: Not a bug +Status: Feedback Type: Bug Package: Variables related Operating System: windows PHP Version: 7.3.11 Block user comment: N Private report: N New Comment: Sorry yes, you're right, it's a pre-increment in there, and the reference does (did) matter. 5 is the correct output - I'm not sure how it came up with 6 before. Previous Comments: ------------------------------------------------------------------------ [2019-11-18 16:22:23] cmb@php.net > It's about the undefined execution order. I don't think so, since it doesn't matter whether (++$a) is evaluated before (++$a) or the other way round. It rather seems to me that PHP < 7 got confused by the reference. ------------------------------------------------------------------------ [2019-11-18 15:12:35] requinix@php.net It's about the undefined execution order. https://www.php.net/manual/zh/language.operators.precedence.php > Operator precedence and associativity only determine how expressions are grouped, they do not > specify an order of > evaluation. PHP does not (in the general case) specify in which order an expression is > evaluated and code that > assumes a specific order of evaluation should be avoided, because the behavior can change > between versions of PHP > or depending on the surrounding code. > > Example #2 Undefined order of evaluation <?php $a = 1; echo $a + $a++; // may print either 2 or 3 $i = 1; $array[$i] = $i++; // may set either index 1 or 2 ?> (the page is already marked as needing a translation update) ------------------------------------------------------------------------ [2019-11-18 13:11:13] cmb@php.net Isn't 5 the output one would expect? ------------------------------------------------------------------------ [2019-11-18 09:35:47] 1003674174 at qq dot com Description: ------------ php5.6echo的值是6，php7的值是5 Test script: --------------- $a=1;$b=&$a;echo (++$a)+(++$a);exit; ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=78829&edit=1