(PHP 5 >= 5.4.0, PHP 7) Checks if the trait exists

(PHP 4, PHP 5, PHP 7) Checks if the class has been defined

(PHP 4, PHP 5, PHP 7) Gets the class methods' names

(PHP 4, PHP 5, PHP 7) Get the default properties of the class

(PHP 4, PHP 5, PHP 7) Returns an array with the name of the defined classes

(PHP 4 >= 4.2.0, PHP 5, PHP 7) Checks if the object is of this class or has this class as one of its parents

(PHP 5 >= 5.3.0, PHP 7) the "Late Static Binding" class name

(PHP 5, PHP 7) Attempt to load undefined class

(PHP 4, PHP 5) Call a user method on an specific object

(PHP 4 >= 4.0.5, PHP 5) Call a user method given with an array of parameters