title: How backwards compatible is php 5 with php 4?
body: <p>I work on a code base written in php 4. I'd like to go through the process of upgrading the code to php 5 (the latest version my host provides). I'm wondering if anyone else has gone through a similar upgrade experience and can share what gotchas/pitfalls there are, what has to change in my code, what is not backwards compatible between the two versions?</p>