(PHP 5 >= 5.3.0, PHP 7) Returns status of the circular reference collector

(PHP 4, PHP 5, PHP 7) Prints out the credits for PHP

(PHP 5, PHP 7) Returns a unique identifier for the current thread

Dummy for main() There is no function named

(PHP 4 >= 4.2.0, PHP 5, PHP 7) Gets all configuration options

(PHP 5 >= 5.2.1, PHP 7) Returns directory path used for temporary files

(PHP 4, PHP 5, PHP 7) Gets the inode of the current script

(PHP 4, PHP 5, PHP 7) Find out whether an extension is loaded

(PHP 4, PHP 5) Alias of

(PHP 4 >= 4.3.0, PHP 5, PHP 7) Gets options from the command line argument list