Difference between php 4 and php 5? [closed]

Answer 1

Here is a basic overview of the release history. PHP 5 was a big change.

I won't go into huge detail on the differences though since PHP 4 is deprecated. Stick with PHP 5 & MySQL 5. I'd be surprised if a webhost didn't offer PHP 5 as well as 4. 4 should only be used with legacy code and should never be used for new development.

Answer 2

Why not take a look at the PHP docs:

http://www.php.net/manual/en/migration5.php

http://www.php.net/manual/en/faq.migration5.php

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

With regards to MySQL you can track changes in versions here:

http://dev.mysql.com/doc/mysqld-version-reference/en/key-changes.html

Major new features added to MySQL 5.0 and 5.1 that may not work/won't work in 4.x can be located here:

MySQL 5.0 - http://dev.mysql.com/doc/refman/5.0/en/mysql-nutshell.html

MySQL 5.1 - http://dev.mysql.com/doc/refman/5.1/en/mysql-nutshell.html

Answer 3

PHP version 5 I look at as when PHP became a real language, for a whole bunch of reasons, but most importantly because it became possible to write respectable Object Oriented code.

But don't deemphasize the difference between MySQL 4 and 5 - I think it's even deeper and more significant. MySQl 5 was when MySQL became a real relational database platform, for a whole bunch of reasons, but most importantly because it became possible to write fully expressive SQL statements (starting with full subquery support).

Just those two limitations on the earlier versions are, I hope, showstoppers for you. There's no reasonable excuse for accepting less than version 5 of either.