PHP4 on PHP5 server

[Zeggy]

I'm just wondering, since I never got a definitive answer to this question.

Is there any circumstance where a PHP4 script would not work on a PHP5 server?

[Rimmy]

Aren't these things usually backwards compatible?

[danielOut]

http://us3.php.net/manual/en/migration5.incompatible.php

Hope that helps

[JGadrow]

Also, be sure to check the php.ini settings for the new server as some of your code may have been dependent upon it. For example, if you're used to register_globals being turned on or perhaps you're using utf-8 encoding but you've been coding your string handling using the basic handlers due to the ini setting aliases for those functions to the mbstring functions.

[Chris]

Yes, it happens to me once. Do not remember what it was exactly, but it was connected to handles or references. It was only one problem in a whole gamescript and it was partially due to my improper code (PHP5 is more strict than PHP4). So I would say such occurences are rare and swithing to PHP5 would be without problems in 99% of cases.

[Boozerbear]

I'm just wondering, since I never got a definitive answer to this question.

Is there any circumstance where a PHP4 script would not work on a PHP5 server?

well, not so much "not work" as "works in an unexpected manner".

The two things I had to deal with is the changes in MySQL: namely a change in the format of the TIMESTAMP field and the fact that now *all* integer-type fields have a tendency to roll over to max value if you set them to UNSIGNED and subtract from the value to get a result that's negative. This previously only occurred with BIGINT fields, but now they all do it.

PHP4 to PHP5 was no problem. MySQL 4 to MySQL 5 was a bit more challenging. (: