PHP generally supports single type of inheritance.Allthough All inheritance are supported but multiple not supported and replace by inheritance used in PHP5.

Array_merge():The array_merge() function merges arrays together, returning a single, unified array.

Array_slice(): The array_slice() function returns a section of an array based on a starting and ending offset value.

Class: Classes are intended to represent those real-life items that coder like to manipulate within an application.

Object: A class provides a basis from which you can create specific instances of the entity the class models, better known as object.That means, an instance of class is called object . Such as $employee = new Employee();

The use of the function session_start() lets us activating a session.

No, a parent constructor have to be called explicitly as follows:

parent::constructor($value)