Oop in c++ lecture 1

Basic Concepts of OOPs
Course Name:
Object Oriented
Programming with
C/C++
Course Code:
19008600
Computer Science
Engineering(Sem-III)
Faculty Name:
Zaiba Khan
Assistant Professor(CSE)
School of
Engineering &
Technology

Why do we need Object Oriented
Programming ?
 Object Oriented Programming was
developed because limitations were
discovered in earlier approaches to
programming.

Procedure Oriented Programming(POP)
 C, Pascal, Fortan and similar
languages are procedural languages.
 Each statement in the language tells
the computer to do something:
◦ Get some input
◦ Add these numbers
◦ Divide by 6
◦ Display that output
A program in a procedural language is a list
of instructions.

 Division into Functions:
◦ Procedural program is divided into
functions.
◦ Each function has clearly defined purpose
and a clearly defined interface to the other
functions in the program.
◦ It can be further extended by grouping a
number of functions together into a larger
entity called a module.
What are
functions?

 Division into functions:

 Characteristics:
◦ Emphasis is on doing things (Algorithms)
◦ Large programs are divided into smaller
programs known as functions.
◦ Most of the functions share global data.
◦ Functions transform data from one form to
another.
◦ Top-down approach is used in program
design.
What is Top-
down
approach?

 Top Down Approach:
◦ It is a process of breaking the overall
procedure or task into component parts
(modules) then subdivide each component
module until the lowest level of detail has
been reach.
◦ For Example: The payroll system of a
company can contain the following modules
or tasks
 Master file
 Earning
 Deductions
 Taxing
 Net Earning
 Print reports

 Drawbacks:
◦ Since every function has complete access
to the global variables, the new
programmer can corrupt the data accidently
by creating functions.
◦ We can access the data of one function from
other since, there is no protection.
◦ In large data program it is very difficult to
identify what data is used by which function.
◦ Similarly, if new data is to be added, all the
function needed to be modified to access the
data.
◦ It does not model with the real world problem
very well.

Object Oriented
Programming(OOP)
 OOP was introduced to overcome the
flaws in the procedural approach to
programming.
 Such as like reusability and
maintainability.
 The basic fundamental idea behind
OOP programming is to combine into
single unit both data and the functions
that operate on the data.
 Such unit is called Object.

Object Oriented
Programming(OOP)
 In OOP, problem is divided into the
number of entities called objects and
then builds data and functions around
these objects.
 Data of an object can be accessed
only by the functions associated with
that object.
 Communication of the objects done
through function.

Object Oriented
Programming(OOP)
 Characteristics:
◦ Emphasis more on data rather than
procedure.
◦ Programs are divided into entities called
object.
◦ Data is hidden and cannot be accessed by
external functions.
◦ Objects communicate with each through
functions.
◦ New data and functions can be easily added
whenever necessary .
◦ Follow bottom up design in program design.

Object Oriented
Programming(OOP)
 Bottom Up Approach:
◦ It is a reverse process of Top Down approach.
◦ Lower level task are carried out first and then
integrated to provide the solution of a single
program.
◦ Lower level structures of a program are evolved first.
◦ After that higher level structures are created.
◦ It promotes code reuse.

Summary:
Difference between POP & OOP
Procedural Oriented
Programming(POP)
 In POP, program is divided into
small parts called functions.
 In POP, Importance is not given to
data but to functions as well as
sequence of actions to be done.
 POP follows Top Down approach.
 POP does not have any access
specifier.
 In POP, Data can move freely from
function to function in the system.
 To add new data and function in
POP is not so easy.
 POP does not have any proper way
for hiding data so it is less secure.
 Example of POP are : C, VB,
FORTRAN, Pascal.
Object Oriented Programming(OOP)
 OOP, program is divided into parts
called objects.
 In OOP, Importance is given to the
data rather than procedures or
functions because it works as a real
world.
 OOP follows Bottom Up approach.
 OOP has access specifiers named
Public, Private, Protected, etc.
 In OOP, objects can move and
communicate with each other
through member functions.
 OOP provides an easy way to add
new data and function.
 OOP provides Data Hiding so
provides more security.
 Example of OOP are : C++, JAVA,
VB.NET, C#.NET.

Character Set in C++
 There are four types of Character Set:
Character Set
1.Ank Letters Uppercase A-Z
Lowercase a-z
2. Digits All digits 0-9
3. Special
Characters
All symbols , : ,
;,!, !,$, &,,*,%,@,
{},[],()
4. White Spaces Blank Space,
Horizontal tab,
New Line

Constant in C++
 It is an identifier whose value cannot be changed at the
execution time of program.
 It can simply be defined as “constant “ can be used to
represent as fixed values in a C++ program. Classification is
as follows:

Variables in C++
 Variables are used to store values.
 Variable name is the name of memory location where value is
store.
 It must be alphanumeric , only underscore is allowed in a
variable name.
Syntax:
Data-Type Variable Name
Examples:
int a;
float b;
char c;
Initialization of Variable:
Means assigning value to declared variable.
For example:
A= 10;
B=4.5;
C=‘a’;
Do You Know?
If no input
values are
assigned by the
user than
system will gives
a default value
called garbage
value.

Data Types in C++
 A keyword to identify type of data. It is used for storing the
input of the program into the main memory (RAM)of the
computer.
 There are three categories of data type. They are

Data Types in C++(Cont.)
 Primitive Data Types
◦ These are the data types whose variable can hold maximum one value at a time.
 Derived Data Types
◦ They are derived from fundamental data type.
◦ It allow us to store multiple values of same type in one variable BUT never allows to
store many values of different types.

Oop in c++ lecture 1

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