Object Oriented Programming in PHP : Inheritance

PHP class definitions can optionally inherit from a parent class definition by using the extends clause. The syntax is as follows:

 class Child extends Parent {
     <definition body>
  }

The effect of inheritance is that the child class (or subclass or derived class) has the following characteristics:

• Automatically has all the member variable declarations of the parent class.
• Automatically has all the same member functions as the parent, which (by default) will work the same way as those functions do in the parent.

Following example inherit Books class and adds more functionality based on the requirement.

class Novel extends Books{ var publisher; function setPublisher($par){ $this->publisher = $par; } function getPublisher(){ echo $this->publisher. "<br />"; } }

Now apart from inherited functions, class Novel keeps two additional member functions.