Aliasing See Variable assignment by reference . The majority of the most popular PHP modules have already been converted to use this enhanced interface. Automatic resource de-allocation See Reference counting . Boolean type PHP 4.0 supports the Boolean type. There are some minor differences due to the improved architecture of PHP 4, but most people will probably not bump into them.
Configuration See the php.ini file .
Encryption supported Both full encryption, using the mycrypt library, and hash encryption are supported by PHP 4.0. Blowfish, TripleDES, MD5, and SHA1 are some of the encryption algorithms that can be used. Usually, you would not want to provide a web interface for downloading a large file via a modem connection. The following are examples of functions that either are new to PHP 4.0 or have had their functionality increased. A fallback system for HTTP session management is built into PHP 4.0.