(PHP 4, PHP 5, PHP 7) Gets the value of an environment variable

(PHP 4, PHP 5, PHP 7) Returns an array with the names of included or required files

(PHP 4, PHP 5, PHP 7) Sets the value of a configuration option

(PHP 4, PHP 5, PHP 7) Returns an array with the names of all modules compiled and loaded

(PHP 5 >= 5.3.0, PHP 7) Activates the circular reference collector

(PHP 5 >= 5.2.0, PHP 7) Returns the peak of memory allocated by PHP

(PHP 5, PHP 7 >= 5.5.0, PHP 7) Sets the process title

(PHP 4, PHP 5) Sets the current active configuration setting of magic_quotes_runtime

(PHP 4 >= 4.1.0, PHP 5, PHP 7) Returns an associative array with the names of all the constants and their

(PHP 4 >= 4.3.0, PHP 5, PHP 7) Gets the current include_path configuration option