(PHP 4 >= 4.1.0, PHP 5 < 5.4.0) Import GET/POST/Cookie variables into the global scope

(PHP 4, PHP 5, PHP 7) Find whether the type of a variable is integer

(PHP 4 >= 4.0.6, PHP 5, PHP 7) Verify that the contents of a variable can be called as a function

(PHP 4, PHP 5, PHP 7) Finds whether a variable is a resource

(PHP 4, PHP 5, PHP 7) Determine whether a variable is empty

(PHP 4, PHP 5, PHP 7) Determine if a variable is set and is not NULL

(PHP 4 >= 4.2.0, PHP 5, PHP 7) Get float value of a variable

(PHP 4, PHP 5, PHP 7) Get the type of a variable

(PHP 4, PHP 5, PHP 7) Unset a given variable

(PHP 4 >= 4.0.4, PHP 5, PHP 7) Returns an array of all defined variables