PHP OOP 4/5 Compatibility?

Question

I've read that major changes were made in PHP 5 to the OO structure, so I'm concerned (before taking up OOP PHP) that users would need a specific version of PHP installed to run my application (either 4 or 5). Up until now this hasn't really been an issue as it's just been differences like missing functions or different return values.

So would an OOP structured PHP application designed for PHP 4 run fine under PHP 5, or vice versa?

Answer 1

For the most part, things written using PHP 4 OOP should work in PHP 5.

However, support for PHP 4 has been dropped many years ago. It doesn't even receive security fixes anymore. There is no reason whatsoever to run PHP 4 today.