INTRODUCTION TO OBJECT ORIENTATION AND C++

C++ is an Object Oriented Programming Languages (OOPL). It was developed by Mr.Bjarne Stroustrup in 1980 at Bell Laboratories. It is an extension of C-Language. It was initially named as ‘C with Classes’.

NEED FOR OOP APPROACH:

Object Oriented Programming is an approach to program organization and development that attempts to eliminate the pitfalls of Procedure Oriented Programming

With advent of languages such as C became very popular and it was the main technic 0f 1980’s.

Structured Programming was a popular tool for developing moderately complex programs

As the size and complexity of program increase the structured programming approach failed in developing big tree programs that are easy to maintain and reusable.

Once the program exceeds 20,000 lines of code it become very difficult to group the essence of the program in totality.

Out of the total cost of software around 90% is spent on debugging and maintenance

Only 2% of software objects undertaken by U.S. Defence Department in 1970’s worked successfully.

This increasing complexity of programs as necessitated for the development of new programming approach of OOP. It is such an approach that eliminates the drawback of Structured Programming Approach.

MAIN ADVANTAGE OF OOP OVER SOP

In SOP, most of the data is created as global; hence all the functions in the program can access the data. If there are 100 of functions if any function mismanipulates the data by mistake it will be very difficulty to check the code of all these functions to find out the error. As the complexity of the program increases it will become almost impossible to find out the bugs.

Procedure Oriented Approach

In OOP, most of the data will be private only a few functions, can manipulate the data. The data and functions that operate on the data will be encapsulated as a single unit and such a unit is called as Object. If any outside function want to access the data it has to make use of the few functions, which can access the data i.e., the outside functions cannot directly access the data. In this approach, if data is mismanipulated by mistake we need to check the code of only a few functions. Therefore, the debugging process is considerably reduced.

Object Oriented Approach

 

DIFFERENCES BETWEEN POP AND OOP

 

Procedure Oriented Programming	Object Oriented Programming
Emphasis is on doing things	Emphasis is on data rather than procedures
Programs are divided into small things known as functions	Programs are divided into what are known as Objects
Data move openly around the system from function to function	Data is hidden and cannot be accessed by external functions
Debugging Process is very difficult	Debugging Process is very easy
Follows top-down approach in program design	Follows bottom-up approach in program design
Most of the functions share global data	The data of an object can be accessed only by the functions that are associated with it

 

Reference Variable:  It Provides an alias for previously defined variable.

Ex:- int total=500;

     Int &sum=total;

Syn: datatype &ref_name=var_name;

Both variables refer to the same data in the memory. If a change made to 1 variable will effect another variable.

Operators in C++:

>>->Extraction

<<->Insertion

:: ->scope resolution

.

:->Inheritance Operator

&->Reference Operator

new

delete

->*àPointer to member

 

INTRODUCTION TO C++

        C++ is an OOP language developed by Bjarne Stroustrup of Denmark at AT & T Bell Laboratories in New Jersey, USA in 1982.Stroustrup, an admirer of simula67 & a strong supporter of C wanted to combine the best of both languages & create a more powerful language that support Object – Oriented Programming features.

 DIFFERENCES BETWEEN C AND C++ 

C	C++
In C, main function return a value of void type	In C++, it returns a value of integer type
Prototyping for functions and procedures are optional	It is an strictly typed language which makes compulsory for specifying prototype and procedures
C doesn’t give importance to data	It uses the concept of data hiding which restricts data to move away from the entity definition
C doesn’t support declaration of variables inline	It allows inline declaration wherever the user wants
Extension of source file is .c	Extension of source file is .cpp
The basic building block is a function	The basic building block is an object
C does not support future extension	It supports the concept of Inheritance through which new features can be added without redeclaring the existing one
C doesn’t support multiple definition for the same name which is basically overloading	C++ supports overloading both for a function and operators.

FEATURES OF OBJECT ORIENTED LANGUAGE

• Emphasis is on data rather than procedure.
• Programs are divided into what are known as objects.
• Data structures are designed such that they characterize the objects.
• Functions that operate on the data of an object are tied together in the data structure.
• Data is hidden and cannot be accessed by external functions.
• Objects may communicate with each other through functions.
• New data and functions can be easily added whenever necessary.
• Follows bottom-up approach in program design.

 BENEFITS OF OBJECT ORIENTED PROGRAMMING (OOP) 

• The concept of a data class makes it possible to define subclasses of data objects that share some or all of the main class characteristics. Called inheritance, this property of OOP forces a more thorough data analysis, reduces development time, and ensures more accurate coding.
• Since a class defines only the data it needs to be concerned with, when an instance of that class (an object) is run, the code will not be able to accidentally access other program data. This characteristic of data hiding provides greater system security and avoids unintended data corruption.
• The definition of a class is reusable not only by the program for which it is initially created but also by other object-oriented programs (and, for this reason, can be more easily distributed for use in networks).
• The concept of data classes allows a programmer to create any new data type that is not already defined in the language itself.
• 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.
• It is easy to partition the work in a project based on objects.
• Object-Oriented systems can be easily upgraded from small to large systems.
• Message passing techniques for communication between objects makes the interface descriptions with external systems much simpler.
• The principle of data hiding helps the programmer to build secure programs that cannot be invaded by code in other parts of the program.
• Software complexity can be easily managed.

 APPLICATIONS OF OOPS

• Real – time Systems
• Simulation and modeling
• Object – Oriented databases
• Hypertext, hypermedia and expertext
• Artificial Intelligence
• Neural works
• CIM/CAM/CAD systems
• Office automation systems
• Decision support
• Parallel Programming