C++ chapter 1

Object Oriented Programming
Using C++
By
Jasvinder Pal Singh
Assistant Professor
Department of Computer Science and Engineering

Object Oriented Language
Software Evolution
Procedure Oriented Language
Assembly Language
Machine Language
1,0

Machine Language
0000 1001 1100 0110 1010 1111 0101 1000
1010 1111 0101 1000 0000 1001 1100 0110
1100 0110 1010 1111 0101 1000 0000 1001
0101 1000 0000 1001 1100 0110 1010 1111

Assembly Language
(PDP-11 Programmed Data Processor)

Assembly Language
GCD: TST B
BEQ SIMPLE
MOV A, R5
SXT R4
DIV B, R4
MOV B, A
MOV R5, B
CALL GCD
SIMPLE: RETURN

Procedure Oriented Programming(POP)
•Conventional programming language such as COBOL, FORTRAN and C is
commonly known as Procedure-oriented programming
.
•The primary focus is on functions.
Main Function
Function-1 Function-2 Function-3
Function-4 Function-5

•Procedure oriented programming basically consists of writing a list of instructions for the
computer to follow and organizing these instructions into groups known as functions
•More importance to Functions very little attention to data that are being used by the
functions.
Relationship of data and functions in Procedural Programming
Global Data Global Data
Function-1
Data
Function-2
Data
Function-3
Data

•Data is not secure.
•Global data are more vulnerable to the changes
by the function.
•In large programs , it is very difficult to identify
what data is used by which function.
•Does not model real world problems very well.

Characteristics of POP:
•Emphasis is on doing things
•Large programs are divided into smaller programs known as
functions.
•Functions share global data.
•Work on top- down approach.

#include<stdio.h>
#include<conio.h>
int data; // Global Data
main()
{
clrsrcr();
printf("%d",data);
fun_1();
fun_2();
getch();
}
fun_1()
{
data++;
printf("%d",data);
}
fun_2()
{
data++;
printf("%d",data);
}

•Invention of Object Oriented Approach is to remove flaws of
Procedural approach.
•OOP treats data as a critical element and does not allow to move
freely.
•It ties data more closely to the functions data operate on data and
protect it from accidental modification from outside functions called
objects.
•OOP decompose a problem into a number of entities called objects
and build data and functions around these objects.
•The data of an object can be accessed only by the functions.
•Functions can communicate with functions of other objects.

Data
Functions
Data
Functions
Data
Functions
Object A Object B
Object C
Communication
Organization of data and functions in OOP

Characteristics of OOP
•Emphasis is on data rather than procedure.
•Programs are divide into objects.
•Data is hidden and cannot be accessed by external
functions.
•Objects can communicate with each other through
functions.
•New data and functions can be easily added whenever
necessary.
•Follows bottom-up approach in program design.

Features of Object Oriented
Programming(OOP)
•Objects
•Classes
•Data Abstraction and Encapsulation
•Inheritance
•Polymorphism
•Dynamic Binding
•Message Passing

Objects:
•This is the basic run-time entities in an object oriented programming.
•That is both data and function that operate on data are bundled as a unit called as
object.
•Program objects should be chosen such that they match closely with the real- world
objects.
•Objects take up space in the memory and have an associated address like structure
in C.
Object: STUDENT
DATA
Name
DOB
Marks
FUNCTIONS
Total
Average
Display
Total
Average
Display
STUDENT
Two ways of representing an object

Classes
•The entire set of data and code of an object can be made a user-
defined data type with the help of a class.
•Objects are variable of type class.
•Once a class has been defined we can create any number of objects
belonging to that class.
•A class is thus a collection of objects of similar type.
•Classes are user-defined data types and behave like the built-in types
of a programming language.
e.g: Fruits mango , apple.

Data Abstraction and Encapsulation
•The wrapping up of data and function into a single unit (called class) is known as
encapsulation.
•Data and encapsulation is the most striking feature of a class.
•The data is not accessible to the outside world, and only those functions which are
wrapped in the class can access it.
•Functions provide the interface between the object’s data and the program.
•Insulation of the data 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
•The attributes are some time called data members and The functions that operate
on these data are sometimes called methods or member function.

Inheritance
•This is the process by which a class can be derived from a base class with all
features of base class and some of its own.
•This increases code reusability.

Types of Inheritance
In C++, we have 5 different types of Inheritance.
Namely,
1. Single Inheritance
2. Multiple Inheritance
3. Hierarchical Inheritance
4. Multilevel Inheritance
5. Hybrid Inheritance (also known as Virtual
Inheritance)

Types of Inheritance
Multiple Inheritance
Multilevel Inheritance
Hierarchical Inheritance
Hybrid Inheritance

Polymorphism
•Polymorphism is another important OOP concept .
•Polymorphism means the ability to take more than one form.
•An operation may exhibit different behavior is 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
Example of Polymorphism

Polymorphism
Types of Polymorphism

Dynamic Binding
•Binding refers to the linking of a procedure call to the
code to be executed in response to the call.
•Dynamic binding also known as late binding, means that
the code associated with a given procedure call is not
known until the time of the call at Run-Time.

Message Passing
•A message for an object is a request for execution of a procedure .
•Invoke a function(procedure) in the receiving object that generates
the desired result.
•Message passing involves :
1. Specifying name of the object.
2. Name of the function(message).
3. Information to be sent.

object-oriented languages into the following two
categories:
1. Object-based programming languages, and
2. Object-oriented programming languages.

1. Object-based programming is the style of programming that
primarily supports encapsulation and object identity. Major
feature that are required for object based programming are:
• Data encapsulation
• Data hiding and access mechanisms
• Automatic initialization and clear-up of objects
• Operator overloading
Languages that support programming with objects are said to the
objects-based programming languages. They do not support
inheritance and dynamic binding. Ada is a typical object-based
programming language.

2. Object-oriented programming language incorporates all
of object-based programming features along with two
additional features
1. inheritance and
2.dynamic binding.
Object-oriented programming can therefore be
characterized by the following statements:
Object-based features + inheritance + dynamic binding

Applications of OOP
The promising areas of application of OOP include:
•Real-time system
• Simulation and modeling
• Object-oriented data bases
• Hypertext, Hypermedia,
• AI and expert systems
• Neural networks and parallel programming
• Decision support and office automation systems
• CIM/CAM/CAD systems

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