OOPs:Object oriented programming

Object oriented programming is known as OOPs.

OOP is a method of implementation in which programs are organized as co-operative collections of objects, each of which represents an instance of some class and whose classes are all members of a hierarchy of classes united through the property called inheritance.

Three important concepts about OOP are objects, classes and inheritance.

Structured Programming views the two core elements -Data & Functions as two separate entities.  Object oriented programming views them as a single entity. OOP is a new way of solving problems with computers.  OOP languages provide the programmer the ability to create class hierarchies, instantiate co-operative objects collectively working on a problem to produce the solution and send messages between objects to process themselves.

The fundamental features of the OOPs are the following:

§  Encapsulation

§  Data Abstraction

§  Inheritance

§  Polymorphism

§  Message Passing

Encapsulation:  A mechanism that associates the code and the data it manipulates into a single unit and keeps them safe from external interference and misuse.

Data Abstraction:  The technique of creating new data types that is well suited to an application to be programmed. It provides the ability to create user-defined data types, for modeling a real world object, having the properties of built in data types and a set of permitted operators.

Inheritance:   It allows the extension and reuse of existing code without having to rewrite the code from scratch. Inheritance involves the creation of new classes (derived classes) from the existing ones (base classes), thus enabling the creation of a hierarchy of classes that stimulate the class and subclass concept of the real world. The new derived class inherits the members of the base class and also adds its own.

Polymorphism:  It allows a single name/operator to be associated with different operations depending on the type of data passed to it. In C++ it is achieved by function over loading,operator over loading and dynamic binding(virtual functions).

Message Passing: The process of invoking an operation on an object. In response to a message, the corresponding method (function) is executed in the object.

OBJECTS

            An object can be a person, a place or a thing with which the computer must deal. Some objects may correspond to real-world entities such as students, employees, bank accounts inventory items etc.  Every object will have data structures called attributes and behaviour called operations.

            Consider the object having the attributes: Account Number, Account type, Name, Balance and Operations: Deposit, Withdraw, Enquire.

CLASSES

            The objects with the same data structure(attributes) and behavior (operations) are grouped into a class.  All those objects possessing similar properties are grouped into the same unit.

            Every object is associated with data and functions which define meaningful operations on that object.