Object oriented programming - Concepts - Benefits - Applications

The Object Oriented programming is an approach that provides a way of modularizing programs for creating partitioned memory area for both data and methods that can be used as templates for creating copies of such modules on demand.

The OOP treats data as a critical element in the program development and does not allow it flow freely around the system. It combined data and methods very closely to work together. And give protection from other members.

The OOP allows us decompose a problem into a number of entities called as Objects. The combination of data and methods make up an Object. The private-data of an object can be accessed by only methods in that object. The public-methods of an object can be accessed by the methods of another object.

The programs in OOPS, classified into classes & Objects. The classes & objects enable Data hiding through Encapsulation & Data-abstraction, Reusability through Inheritance. Polymorphism enables methods and operators to perform different activities in different situations.

Ø  Basic Concepts of Object Oriented Programming

Some of the concepts used extensively in object-oriented programming are:

• Objects

• Classes

• Data abstraction and encapsulation

• Inheritance

• Polymorphism

• Dynamic binding

• Message passing

Objects

Objects are the basic run time entities in an object-oriented system. They may represent a person, a place, a bank account, a table of data or any item that the program has to handle.

Programming problem is analyzed in term of objects and the nature of communication between them.

Objects take up space in the memory and have an associated address. When a program is executed, the objects interact by sending messages to one another.

Each object contain data, and code to manipulate data. Objects can interact without having to know details of each other’s data or code.

Class

The entire set of data and code of an object can be made a user-defined data type with the help of class. Objects are variables of the type class.

Once a class has been defined, we can create any number of objects belonging to that class. Each object is associated with the data of type class with which they are created. A class is thus a collection of objects similar types.

The syntax used to create an object is not different then the syntax used to create an integer object in C.

Example: If student is a class and s1 is the object

                          student   s1;

will create object s1 belonging to class student.

Data Abstraction and Encapsulation

The wrapping up of data and function into a single unit (called class) is known as encapsulation.

The data is not accessible to the outside world, and only those functions which are wrapped in the class can access it. These functions provide the interface between the object’s data and the program. This insulation of the data from direct access by the program is called data hiding or information hiding.

Abstraction refers to the act of representing essential features without including the background details or explanation. Classes use the concept of abstraction.

Inheritance

Inheritance is the process by which objects of one class acquired the properties of objects of another classes.

In OOP, the concept of inheritance provides the idea of reusability. This means that we can add additional features to an existing class without modifying it. This is possible by deriving a new class from the existing one. The new class will have the combined feature of both the classes.

Polymorphism

Polymorphism, a Greek term, means the ability to take more than on form. Polymorphism is another important OOP concept.

An operation may exhibit different behavior in different instances. The behavior depends upon the types of data used in the operation. The process of making an operator to exhibit different behaviors in different instances is known as operator overloading.

Using a single function name to perform different type of task is known as function overloading.

Polymorphism plays an important role in allowing objects having different internal structures to share the same external interface. Polymorphism is extensively used in implementing inheritance.

Dynamic Binding

Binding refers to the linking of a procedure call to the code to be executed in response to the call. Dynamic binding means that the code associated with a given procedure call is not known until the time of the call at run time. It is associated with polymorphism and inheritance.

Message Passing

An object-oriented program consists of a set of objects that communicate with each other. Objects communicate with one another by sending and receiving messages.

A Message for an object is a request for execution of a procedure, and therefore will invoke a function (procedure) in the receiving object that generates the desired results.

Message passing involves specifying the name of object, the name of the function (message) and the information to be sent.

Example:

Employee.salary(name);

Here Employee is a class, salary is a method and name is the information.

Ø  Benefits of OOP

OOP offers several benefits to both the program designer and the user. This technology promises greater programmer productivity, better quality of software and lesser maintenance cost. The principal advantages are:

-          Through inheritance, we can eliminate redundant code extend the use of existing Classes.

We can build programs from the standard working modules that communicate with one another, rather than having to start writing the code from scratch. This leads to saving of development time and higher productivity.

-          The principle of data hiding helps the programmer to build secure program that can not be invaded by code in other parts of a programs. 

-          The data-centered design approach enables us to capture more detail of a model can implemental form. 

-          Object-oriented system can be easily upgraded from small to large system.

-          Message passing techniques for communication between objects makes to interface descriptions with external systems much simpler.

-          Software complexity can be easily managed.

 

Ø  Application of OOP

The promising areas of application of OOP include:

• Real-time system

• Simulation and modeling

• Object-oriented databases

• Hypertext, Hypermedia

• AI and expert systems

• Neural networks and parallel programming

• Decision support and office automation systems

• CAM/CAD systems