Paper Code: Paper Name: OOP with C++
Lesson no: 1 Lesson Name: Introduction of OOP
Author: Pooja Chawla Vetter: Prof. Dharminder Kumar
Unit Structure:
1.1 Software crisis
1.2 Software Evaluation
1.3 POP (Procedure Oriented Programming)
1.4 OOP (Object Oriented Programming)
1.5 Basic concepts of OOP
1.5.1 Objects
1.5.2 Classes
1.5.3 Data Abstraction and Data Encapsulation
1.5.4 Inheritance
1.5.5 Polymorphism
1.5.6 Dynamic Binding
1.5.7 Message Passing
1.6 Benefits of OOP
1.7 Object Oriented Language
1.8 Application of OOP
1.9 Introduction of C++
1.9.1 Application of C++
1.10 Simple C++ Program
1.10.1 Program Features
1.10.2 Comments
1.10.3 Output Operators
1.10.4 Iostream File
1.10.5 Namespace
1.10.6 Return Type of main ()
1.11 More C++ Statements
1.11.1 Variable
1.11.2 Input Operator
1.11.3 Cascading I/O Operator
1.12 Example with Class
1.13 Structure of C++
1.14 Creating Source File
1.15 Compiling and Linking
1.1 Software Crisis
Developments in software technology continue to be dynamic. New tools and techniques
are announced in quick succession. This has forced the software engineers and industry to
continuously look for new approaches to software design and development, and they are
becoming more and more critical in view of the increasing complexity of software
systems as well as the highly competitive nature of the industry. These rapid advances
appear to have created a situation of crisis within the industry. The following issued need
to be addressed to face the crisis:
• How to represent real-life entities of problems in system design?
• How to design system with open interfaces?
• How to ensure reusability and extensibility of modules?
• How to develop modules that are tolerant of any changes in future?
• How to improve software productivity and decrease software cost?
• How to improve the quality of software?
• How to manage time schedules?
1.2 Software Evaluation
Ernest Tello, A well known writer in the field of artificial intelligence, compared the
evolution of software technology to the growth of the tree. Like a tree, the software
evolution has had distinct phases “layers” of growth. These layers were building up one
by one over the last five decades as shown in fig. 1.1, with each layer representing and
improvement over the previous one. However, the analogy fails if we consider the life
of these layers. In software system each of the layers continues to be functional,
whereas in the case of trees, only the uppermost layer is functional
Object Oriented Programming
Procedure- Oriented
Assembly Language
Machine Language
1, 0
Alan Kay, one of the promoters of the object-oriented paradigm and the principal
designer of Smalltalk, has said: “As complexity increases, architecture dominates the
basic materials”. To build today’s complex software it is just not enough to put together a
sequence of programming statements and sets of procedures and modules; we need to
incorporate sound construction techniques and program structures that are easy to
comprehend implement and modify.
With the advent of languages such as c, structured programming became very popular
and was the main technique of the 1980’s. Structured programming was a powerful tool
that enabled programmers to write moderately complex programs fairly easily. However,
as the programs grew larger, even the structured approach failed to show the desired
result in terms of bug-free, easy-to- maintain, and reusable programs.
Object Oriented Programming (OOP) is an approach to program organization and
development that attempts to eliminate some of the pitfalls of conventional programming
methods by incorporating the best of structured programming features with several
powerful new concepts. It is a new way of organizing and developing programs and has
nothing to do with any particular language. However, not all languages are suitable to
implement the OOP concepts easily.
1.3 Procedure-Oriented Programming
In the procedure oriented approach, the problem is viewed as the sequence of things to
be done such as reading, calculating and printing such as cobol, fortran and c. The
primary focus is on functions. A typical structure for procedural programming is shown
in fig.1.2. The technique of hierarchical decomposition has been used to specify the tasks
to be completed for solving a problem.
Function-1 Function-2
Function-8
Function-5
Function-7
Function-4
Function-3
Main Program
Function-6
Fig. 1.2 Typical structure of procedural oriented programs
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. We
normally use flowcharts to organize these actions and represent the flow of control from
one action to another.
In a multi-function program, many important data items are placed as global so that
they may be accessed by all the functions. Each function may have its own local data.
Global data are more vulnerable to an inadvertent change by a function. In a large
program it is very difficult to identify what data is used by which function. In case we
need to revise an external data structure, we also need to revise all functions that access
the data. This provides an opportunity for bugs to creep in.
Another serious drawback with the procedural approach is that we do not model real
world problems very well. This is because functions are action-oriented and do not really
corresponding to the element of the problem.
Some Characteristics exhibited by procedure-oriented programming are:
• Emphasis is on doing things (algorithms).
• Large programs are divided into smaller programs known as functions.
• Most of the functions share global data.
• Data move openly around the system from function to function.
• Functions transform data from one form to another.
• Employs top-down approach in program design.
1.4 Object Oriented Paradigm
The major motivating factor in the invention of object-oriented approach is to remove
some of the flaws encountered in the procedural approach. OOP treats data as a critical
element in the program development and does not allow it to flow freely around the
system. It ties data more closely to the function that operate on it, and protects it from
accidental modification from outside function. OOP allows decomposition of a problem
into a number of entities called objects and then builds data and function around these
objects. The organization of data and function in object-oriented programs is shown in
fig.1.3. The data of an object can be accessed only by the function associated with that
object. However, function of one object can access the function of other objects.
Organization of data and function in OOP
Object A Object B
Communication
DATA
FUNCTION
DATA
FUNCTION
Object
FUNCTION
DATA
Some of the features of object oriented programming are:
• 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 ties together in the data
structure.
• Data is hidden and cannot be accessed by external function.
• Objects may communicate with each other through function.
• New data and functions can be easily added whenever necessary.
• Follows bottom up approach in program design.
Object-oriented programming is the most recent concept among programming
paradigms and still means different things to different people.
1.5 Basic Concepts of Object Oriented Programming
It is necessary to understand some of the concepts used extensively in object-oriented
programming. These include:
• Objects
• Classes
• Data abstraction and encapsulation
• Inheritance
• Polymorphism
• Dynamic binding
• Message passing
We shall discuss these concepts in some detail in this section.
1.5.1 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. They may also represent user-defined data such as vectors, time and lists.
Programming problem is analyzed in term of objects and the nature of communication
between them. 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 a record in Pascal, or a structure in c.
When a program is executed, the objects interact by sending messages to one another.
Foe example, if “customer” and “account” are to object in a program, then the customer
object may send a message to the count object requesting for the bank balance. Each
object contain data, and code to manipulate data. Objects can interact without having to
know details of each other’s data or code. It is a sufficient to know the type of message
accepted, and the type of response returned by the objects. Although different author
