Re: Copy On Write and Assign By Reference perform different on PHP5 and PHP7

On Thu, Mar 31, 2016 at 9:47 AM, Huqiu Liao <liaohuqiu@gmail.com> wrote: > I have a question about Assign By Reference and I posted on StackOverflow, > I'd like to know the reason behind it, and I did not get any this kind of > answer, can anyone give me some clues. > Are you asking out of curiosity? Or because you think a new bug has been introduced in PHP7? If the latter, I'd respond by pointing out that the behavior of using multiple operations with side-effects (like pre/post inc/dec) is defined as undefined. That is, while the PHP reference implementation may give you a particular result, you should not rely on that result. If the former, and you're just curious why, it comes down to a very fundamental change in the way PHP7 deals with references. I'd recommend reading Nikita's writeup of the differences between PHP 5 and PHP 7 variables at: https://nikic.github.io/2015/05/05/Internal-value-representation-in-PHP-7-part-1.html -Sara