php 4 to php 5

[spires]

Hi

 

I am still running a server with PHP4, but it has now come to a point where I need to upgrade to PHP5.

However, It would be great if I could get some advice from you guys first.

 

- Will my website that was built in php4 still work?

- is there a list of functions that no longer work?

- What are the chances of my old site breaking?

 

Thanks for your help.

[Daniel0]

You should take a look at:

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

http://www.php.net/manual/en/migration51.php

http://www.php.net/manual/en/migration52.php

 

and possibly http://www.php.net/manual/en/migration53.php if you want to go to PHP 5.3.

[PFMaBiSmAd]

- Will my website that was built in php4 still work?

If is was using the current recommended php.ini settings, it will probably work.

 

- is there a list of functions that no longer work?

See the links Daniel0 posted. All the functions still work. There are only a few minor/obscure incompatible differences.

 

- What are the chances of my old site breaking?

High. Too many web hosts and people writing code under php4 did not follow recommend php.ini changes that occurred over time, in some cases things that were turned off by default a full 7 years ago. Most notably relying on register_globals and not using the $_SESSION variable array. These are actually php configuration changes and nothing to do with the php version.

 

All the features that have been turned off over time still exist in php5 (most have been completely removed in php6 though), so it is  possible in the short term to  configure php5 identically to your php4 system while you correct any code that is dependent on depreciated features.

 

You should probably test your code on an off-line php5 development system that you know is using the current recommend php.ini settings (there is no guarantee that your web host is following the current recommendations under php5) rather than just switching to php5 on your active web site.