PHP 3.0 is rewritten from the ground up. It has a proper parser
that is much more robust and consistent than 2.0's. 3.0 is also
significantly faster, and uses less memory. However, some of
these improvements have not been possible without compatibility
changes, both in syntax and functionality.
In addition, PHP's developers have tried to clean up both PHP's
syntax and semantics in version 3.0, and this has also caused some
incompatibilities. In the long run, we believe that these changes
are for the better.
This chapter will try to guide you through the incompatibilities
you might run into when going from PHP/FI 2.0 to PHP 3.0 and help
you resolve them. New features are not mentioned here unless
necessary.
A conversion program that can automatically convert your old
PHP/FI 2.0 scripts exists. It can be found in the
convertor subdirectory of the PHP 3.0
distribution. This program only catches the syntax changes though,
so you should read this chapter carefully anyway.