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Basic concepts of OOPS and Structure of C++ program

Basic concepts of OOPS and Structure of C++ program:

Before starting to learn C++ it is essential that one must have a basic knowledge of
the concepts of Object oriented programming. Some of the important object oriented
features are namely:

• Objects
• Classes
• Inheritance
• Data Abstraction
• Data Encapsulation
• Polymorphism
• Overloading
• Reusability
In order to understand the basic concepts in C++, the programmer must have a command
of the basic terminology in object-oriented programming. Below is a brief outline of
the concepts of Object-oriented programming languages:

Objects:

Object is the basic unit of object-oriented programming. Objects are identified by
its unique name. An object represents a particular instance of a class. There can be
more than one instance of an object. Each instance of an object can hold its own
relevant data.

An Object is a collection of data members and associated member functions also
known as methods.

Classes:

Classes are data types based on which objects are created. Objects with similar
properties and methods are grouped together to form a Class. Thus a Class represent
a set of individual objects. Characteristics of an object are represented in a class
as Properties. The actions that can be performed by objects becomes functions of the
class and is referred to as Methods.
For example consider we have a Class of Cars under which Santro Xing, Alto and
WaganR represents individual Objects. In this context each Car Object will have its
own, Model, Year of Manufacture, Color, Top Speed, Engine Power etc., which form
Properties of the Car class and the associated actions i.e., object functions like
Start, Move, Stop form the Methods of Car Class.
No memory is allocated when a class is created. Memory is allocated only when an object
is created, i.e., when an instance of a class is created.

Inheritance:

Inheritance is the process of forming a new class from an existing class or base class.
The base class is also known as parent class or super class, The new class that is
formed is called derived class. Derived class is also known as a child class or sub
class. Inheritance helps in reducing the overall code size of the program, which is an
important concept in object-oriented programming.

Data Abstraction:

Data Abstraction increases the power of programming language by creating user defined
data types. Data Abstraction also represents the needed information in the program
without presenting the details.

Data Encapsulation:

Data Encapsulation combines data and functions into a single unit called Class. When
using Data Encapsulation, data is not accessed directly; it is only accessible through
the functions present inside the class. Data Encapsulation enables the important concept
of data hiding possible.

Polymorphism:

Polymorphism allows routines to use variables of different types at different times.
An operator or function can be given different meanings or functions. Polymorphism
refers to a single function or multi-functioning operator performing in different ways.

Overloading:

Overloading is one type of Polymorphism. It allows an object to have different meanings,
depending on its context. When an exiting operator or function begins to operate on
new data type, or class, it is understood to be overloaded.

Reusability:

This term refers to the ability for multiple programmers to use the same written and
debugged existing class of data. This is a time saving device and adds code efficiency
to the language. Additionally, the programmer can incorporate new features to the
existing class, further developing the application and allowing users to achieve
increased performance. This time saving feature optimizes code, helps in gaining
secured applications and facilitates easier maintenance on the application.