In which case we need to use abstract class and interface in php

Question

Abstract class abc{
---
}

I am new to OOP.I want to lean the object oriented programming concept. There is a confusion between abstract classes and interfaces. Where do we have to use this and which condition we have to you abstract and interface class. Please suggest me tutorial links so that i can easily get the functionality. Suppose we are going to drink water because i need it. This is the situation when i need water so i take water. In same case abstract and interface is needed.

Answer 1

• An abstract class is a special kind of class that cannot be instantiated. So the question is why we need a class that cannot be instantiated? An abstract class is only to be sub-classed (inherited from).

  In other words, it only allows other classes to inherit from it but cannot be instantiated. The advantage is that it enforces certain hierarchies for all the subclasses. In simple words, it is a kind of contract that forces all the subclasses to carry on the same hierarchies or standards.

• An interface is not a class. It is an entity that is defined by the word Interface. An interface has no implementation; it only has the signature or in other words, just the definition of the methods without the body.

  As one of the similarities to Abstract class, it is a contract that is used to define hierarchies for all subclasses or it defines specific set of methods and their arguments. The main difference between them is that a class can implement more than one interface but can only inherit from one abstract class. Since C# doesn't support multiple inheritance, interfaces are used to implement multiple inheritance.

Read more - http://www.codeproject.com/Articles/11155/Abstract-Class-versus-Interface