Object Oriented Design and Programming Unit-01

21CSC101T OBJECT ORIENTED DESIGN
AND PROGRAMMING
Unit-1 - Introduction to OOPS
1
Dr.M.Sivakumar, AP/NWC

Course Outcomes (CO)
At the end of this course, learners will be able to:
• CO-1: Create programs using object-oriented approach and
design methodologies
• CO-2: Construct programs using method overloading and
operator overloading
• CO-3: Create programs using inline, friend and virtual
functions, construct programs using standard templates
• CO-4: Construct programs using exceptional handling and
collections
• CO-5: Create Models of the system using UML Diagrams
2

Unit-1 - Introduction to OOPS
1. Object-Oriented Programming - Features of C++
2. I/O Operations, Data Types, Variables-Static, Constants,
Pointers
3. Type Conversions - Conditional and looping statements
4. Arrays - C++ 11 features
5. Class and Objects, Abstraction and Encapsulation,
6. Access Specifiers, Methods
7. UML Diagrams Introduction - Use Case Diagram, Class
Diagram.
8. Practice questions from elab
9. Quiz/Puzzles/Review Questions
3

SESSION-01
Introduction to Object-Oriented Programming, Features of C++
Dr.M.Sivakumar, AP/NWC 4

OBJECT-ORIENTED PROGRAMMING
5

Programming Languages
• Programming a computer involves writing instructions that
enable a computer to carry out a single task or a group of tasks
• Writing these sets of instructions, which are known as programs
or software, requires using a computer programming language
and resolving any errors in the instructions so that the programs
work correctly
• Programs are also frequently called application programs
• Simply applications, because you apply them to a task such as
preparing payroll checks, creating inventory reports, or—as in
the case of game programs—even entertaining someone
6

Programming Languages
• learning a computer programming language requires learning
both vocabulary and syntax.
• The rules of any language make up its syntax.
• When you write programs, you write program statements that
are instructions that are similar to English-language sentences.
7

Types of Programming Languages
• Machine level Language
• Assembly level Language
• High level Language
–Procedure oriented programming(POP) language
–Object oriented programming(OOP) language.
8

Procedure Oriented Programming Language
• Drawbacks
– Global data access
– It does not model real word problem very well
– No data hiding
9

Characteristics of procedure oriented
programming
• Emphasis is on doing things(algorithm)
• 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
• Function transforms data from one form to another
• Employs top-down approach in program design
10

Object Oriented Programming
• Object oriented programming as an
approach that provides a way of
modularizing programs by creating
partitioned memory area for both data and
functions that can be used as templates for
creating copies of such modules on demand
11

12

13

• Combine data and functions into object.
(Member Data & Member Functions)
• Member functions are also called methods.
• Member data are hidden within member
functions.
• Data Encapsulation & Data Hiding.
• Objects interact by sending messages to
each other.
14

Vs Procedural Oriented Programming
Procedure Oriented Programming Object Oriented Programming
program is divided into small parts
called functions
program is divided into parts called objects.
Importance is not given to data but to
functions as well as sequence of
actions to be done.
Importance is given to the data rather than
procedures or functions because it works as a real
world.
follows Top Down approach OOP follows Bottom Up approach.
It does not have any access specifier OOP has access specifiers named
Public, Private, Protected, etc
Data can move freely from
function to function in the system
objects can move and communicate with
each other through member functions.
It does not have any proper way for hiding data so
it is less secure
OOP provides Data Hiding so provides more
security
Overloading is not possible In OOP, overloading is possible in the form of
Function Overloading and Operator
Overloading.
15

Basic concepts of OOPS
1. Objects
2. Classes
3. Data abstraction and encapsulation
4. Inheritance
5. Polymorphism
6. Dynamic binding
7. Message passing
16

Objects
• Software objects model real-world objects or abstract
concepts.
dog, bicycle, queue
• Real-world objects have states and behaviors.
Dogs' states: name, color, breed, hungry
Dogs' behaviors: barking, fetching
• How do software objects implement real-world objects?
Use variables/data to implement states.
Use methods/functions to implement behaviors.
• An object is a software bundle of variables and related methods.
17

Class
• A class is a blueprint or prototype defining the variables
and methods common to all objects of a certain kind.
• An object is an instance of a certain class.
• After you have created a class, you must create an
instance of it before you can use.
• Class variables and class methods.
18

Class and Objects
19

Class and Objects
20

Class and Objects
21

Data abstraction and encapsulation
• It is a mechanism that binds together code and the
data it manipulates, and keeps both safe from
outside interference and misuse
22

23

• Encapsulation is as a protective wrapper that prevents the code and
data from being arbitrarily accessed by other code defined outside
the wrapper
• Access to the code and data inside the wrapper is tightly controlled
through a well-defined interface
24

Inheritance
• Inheritance is the process by which one object acquires the
properties of another object
25

Inheritance
26

Inheritance
27

Polymorphism
• Polymorphism (from Greek, meaning “many forms”) is a feature that
allows one interface to be used for a general class of actions
• The specific action is determined by the exact nature of the situation
28

Polymorphism
29

Dynamic binding
30

Message Passing
 What are Messages?
 Software objects interact and communicate with each
other by sending messages to each other. 31

Benefits of Object-Oriented programming
• Reuse of existing code
• Improved maintainability
• Often a ‘natural’ way to describe a system
32

Applications of Object Oriented Programming
• Client-Server Systems
• Real-Time System
• Object-Oriented Databases
• Simulation and modelling
• AI and expert systems
• Neural networks and parallel programming
33

Introduction to C++
• C++ is a general-purpose programming language that was
developed as an extension of the C programming language with
object-oriented programming features
• C++ was invented by Bjarne Stroustrup in 1979, at Bell
Laboratories in Murray Hill, New Jersey
• C++ is derived from the C language
• C++ provides a combination of low-level features for systems
programming and high-level features for application
development.
• C++ is also the language from which both Java and C# are
derived
35

Sample C++ Program
36

Features of C++
• Object-Oriented Programming (OOP)
• Procedural Programming
• Standard Template Library (STL)
• Memory Management
• Performance
• Portability with relatively few modifications
• Wide Usage
37

Difference between C and C++
C C++
Procedural programming language
Supports both procedural programming (like C)
and object-oriented programming (OOP)
Simpler syntax
Extends the syntax of C by adding new keywords
and features
Memory management is typically done manually
using functions like malloc and free
operators like new and delete for dynamic
memory allocation.
Does not have a standard template library Includes the Standard Template Library (STL)
Does not support function overloading Allows function overloading
Does not have the concept of namespaces Introduces namespaces
printf and scanf for input and output cout for output and cin for input 38

SESSION-02
I/O Operations, Data Types, Variables -Static, Constants - Pointers

I/O OPERATIONS, DATA TYPES, VARIABLES-
STATIC, CONSTANTS

I/O Operations
• C++ I/O operation occurs in streams, which involve transfer of
information into byte
• It’s a sequences of bytes
• Stream involved in two ways
• It is the source as well as the destination of data
• C++ programs input data and output data from a stream.
• Streams are related with a physical device such as the monitor or
with a file stored on the secondary memory.
• In a text stream, the sequence of characters is divided into lines,
with each line being terminated.
• With a new-line character (n) . On the other hand, a binary stream
contains data values using their memory representation.
41

I/O Operations
42
Stream in C
Text Stream Binary Stream

Cascading of Input or Output Operators
43
• << operator –It can use multiple times in the same line.
• Its called Cascading
• Cout ,Cin can cascaded
• For example
• cout<<“n Enter the Marks”;
• cin>> ComputerNetworks>>OODP;

Reading and Writing Characters and Strings
44
• char marks;
• cin.get(marks);//The value for marks is read
• OR
• marks=cin.get();//A character is read and assigned to marks
• string name;
• Cin>>name;
• string empname;
• cin.getline(empname,20);
• Cout<<“n Welcome ,”<<empname;

Formatted Input and
Output Operations
45
Formatted I/O
I/O class function and
flages
Manipulators

Example
46
#include<iostream.h>
#define PI 3.14159
main()
{
cout.precision(3);
cout.width(10);
cout.fill(‘*’);
cout<<PI;
}
Output
*****3.142

Formatting with flags
47
• The setf() is a member function of the ios class that is used to set
flags for formatting output.
• Syntax:
cout.setf(flag, bit-field)
• Here, flag defined in the ios class specifies how the output should
be formatted
• bit-field is a constant (defined in ios ) that identifies the group to
which the formatting flag belongs to.
• There are two types of setf()—one that takes both flag and bit-
fields and the other that takes only the flag .

Formatting with flags
48

Formatting Output Using Manipulators
49

Data Types in C++
50

Variables
51
A variable is the content of a memory location that stores a certain value. A variable is identified or
denoted by a variable name. The variable name is a sequence of one or more letters, digits or
underscore, for example: character_
Rules for defining variable name:
❖ A variable name can have one or more letters or digits or underscore for example character_.
❖ White space, punctuation symbols or other characters are not permitted to denote variable
name.
❖ A variable name must begin with a letter.
❖ Variable names cannot be keywords or any reserved words of the C++ programming language.
❖ Data C++ is a case-sensitive language. Variable names written in capital letters differ from
variable names with the same name but written in small letters.
Static Variables
Local Variables Instance variables
01
02
03
Constant Variables
04

Variables
52
Local Variables Instance Variables Static Variables Constant Variables
Local variable: These are the
variables which are declared within
the method of a class.
Example:
public class Car
{
public:
// Method
void display(int m)
{
// Created a local variable
int model=m;
cout<<model;
}
};
Static variables: Static variables are
also called as class variables. These
variables have only one copy that is
shared by all the different objects in
a class.
Example:
class Car
{
public:
//Static variable
static int tyres;
void init()
{
tyres=4;
}
};
Instance variable: These are the
variables which are declared in a
class but outside a method,
constructor or any block.
Example:
public class Car
{
private:
// Created an instance variable
String color;
Car(String c)
{
color=c;
}
};
Constant is something that
doesn't change. In C language
and C++ we use the keyword
const to make program elements
constant.
Example:
const int i = 10;
void f(const int i);
class Test
{
const int i;
};

CONSTANTS
• Constants are identifiers whose value does not change. While variables can
change their value at any time, constants can never change their value.
• Constants are used to define fixed values such as Pi or the charge on an
electron so that their value does not get changed in the program even by
mistake.
• A constant is an explicit data value specified by the programmer.
• The value of the constant is known to the compiler at the compile time.

Declaring Constants
• Rule 1 Constant names are usually written in capital letters to visually distinguish them
from other variable names which are normally written in lower case characters.
• Rule 2 No blank spaces are permitted in between the # symbol and define keyword.
• Rule 3 Blank space must be used between #define and constant name and between
constant name and constant value.
• Rule 4 #define is a preprocessor compiler directive and not a statement. Therefore, it does
not end with a semi-colon.

Operators
• Arithmetic Operators
• Relational Operators
• Logical Operators
• Bitwise Operators
• Assignment Operators
• Misc Operators

Arithmetic Operators
Operator Description Example
+ Adds two operands A + B will give 30
- Subtracts second operand from the first A - B will give -10
* Multiplies both operands A * B will give 200
/ Divides numerator by de-numerator B / A will give 2
% Modulus Operator and remainder of after an integer division B % A will give 0
++ Increment operator, increases integer value by one A++ will give 11
-- Decrement operator, decreases integer value by one A-- will give 9

Relational Operators
==
Checks if the values of two operands are equal or not, if yes then condition
becomes true.
(A == B) is not true.
!=
Checks if the values of two operands are equal or not, if values are not equal
then condition becomes true.
(A != B) is true.
>
Checks if the value of left operand is greater than the value of right operand,
if yes then condition becomes true.
(A > B) is not true.
<
Checks if the value of left operand is less than the value of right operand, if
yes then condition becomes true.
(A < B) is true.
>=
Checks if the value of left operand is greater than or equal to the value of
right operand, if yes then condition becomes true.
(A >= B) is not true.
<=
Checks if the value of left operand is less than or equal to the value of right
operand, if yes then condition becomes true.
(A <= B) is true.

Logical Operators
&&
Called Logical AND operator. If both the operands are non-zero,
(A && B) is false.
||
Called Logical OR Operator. If any of the two operands is non-zero,
(A || B) is true.
!
Called Logical NOT Operator. Use to reverses the logical state of its
operand. If a condition is true, then Logical NOT operator will make
false.
!(A && B) is true.

Bitwise Operators
&
Binary AND Operator copies a bit to the result if it exists in
both operands.
(A & B) will give 12 which is 0000
1100
| Binary OR Operator copies a bit if it exists in either operand.
(A | B) will give 61 which is 0011
1101
^
Binary XOR Operator copies the bit if it is set in one operand
but not both.
(A ^ B) will give 49 which is 0011
0001
~
Binary Ones Complement Operator is unary and has the effect
of 'flipping' bits.
(~A ) will give -61 which is 1100 0011
in 2's complement form due to a
signed binary number.
<<
Binary Left Shift Operator. The left operands value is moved
left by the number of bits specified by the right operand.
A << 2 will give 240 which is 1111
0000
>>
Binary Right Shift Operator. The left operands value is moved
right by the number of bits specified by the right operand.
A >> 2 will give 15 which is 0000 1111

Assignment Operators
=
Simple assignment operator, Assigns values from right side
operands to left side operand.
C = A + B will assign value of A + B
into C
+=
Add AND assignment operator, It adds right operand to the left
operand and assign the result to left operand.
C += A is equivalent to C = C + A
-=
Subtract AND assignment operator, It subtracts right operand
from the left operand and assign the result to left operand.
C -= A is equivalent to C = C - A
*=
Multiply AND assignment operator, It multiplies right operand
with the left operand and assign the result to left operand.
C *= A is equivalent to C = C * A
/=
Divide AND assignment operator, It divides left operand with
the right operand and assign the result to left operand.
C /= A is equivalent to C = C / A
%=
Modulus AND assignment operator, It takes modulus using two
operands and assign the result to left operand.
C %= A is equivalent to C = C % A

Misc Operators
sizeof() sizeof operator returns the size of a variable.
sizeof(a), where ‘a’ is integer, and will
return 4.
? :
Conditional operator (?). If Condition is true then it returns
value of X otherwise returns value of Y.
,
Comma operator causes a sequence of operations to be
performed. The value of the entire comma expression is the
value of the last expression of the comma-separated list.
. and -> Member operators are used to reference individual members
of classes, structures, and unions.
Cast Casting operators convert one data type to another. int(2.2000) would return 2.
& Pointer operator & returns the address of a variable.
&a; will give actual address of the
variable.
* Pointer operator is pointer to a variable. *var; will pointer to a variable var.

Operators Precedence in C++
Category Operator Associativity
Postfix () [] -> . ++ - - Left to right
Unary + - ! ~ ++ - - (type)* & sizeof Right to left
Multiplicative * / % Left to right
Additive + - Left to right
Shift << >> Left to right
Relational < <= > >= Left to right
Equality == != Left to right
Bitwise AND & Left to right
Bitwise XOR ^ Left to right
Bitwise OR | Left to right
Logical AND && Left to right
Logical OR || Left to right
Conditional ?: Right to left
Assignment = += -= *= /= %=>>= <<= &= ^= |= Right to left
Comma , Left to right

Special Operators
1
2
3
4
In C, the global version of a variable cannot be accessed from within the inner block. C++ resolves this problem by using scope
resolution operator (::), because this operator allows access to the global version of a variable.
The new operator denotes a request for memory allocation on the Heap. If sufficient memory is available, new operator initializes the
memory and returns the address of the newly allocated and initialized memory to the pointer variable.
Since it is programmer’s responsibility to deallocate dynamically allocated memory, programmers are provided delete operator by C++
language.
C++ permits us to define a class containing various types of data & functions as members. To access a member using a pointer in the
object & a pointer to the member.
Scope resolution operator
new Operator
delete Operator
Member Operator

Pointers
• Pointers are symbolic representation of addresses.
• They enable programs to simulate call-by-reference as well as to create and manipulate
dynamic data structures.
• Syntax data_type *pointer_variable;
• Example
int *p,sum;
Assignment
• integer type pointer can hold the address of another int variable
• To assign the address of variable to pointer-ampersand symbol (&)
p=∑
this pointer
hold the adderss of current object
int num;
this->num=num;
Void?
• When used in the declaration of a pointer, void specifies that the pointer is
"universal." If a pointer's type is void* , the pointer can point to any variable that's not
declared with the const or volatile keyword.
64

Pointers
int *ip; // pointer to an integer
double *dp; // pointer to a double
float *fp; // pointer to a float
char *ch // pointer to character
Steps:
(a) We define a pointer variable.
(b) Assign the address of a variable to a pointer.
(c) Finally access the value at the address available in the
pointer variable.
65

Real Time Example
66

How to use it
#include <iostream>
using namespace std;
int main ()
{
int var = 20; // actual variable declaration.
int *ip; // pointer variable
ip = &var; // store address of var in pointer variable
cout << "Value of var variable: ";
cout << var << endl;
// print the address stored in ip pointer variable
cout << "Address stored in ip variable: ";
cout << ip << endl;
// access the value at the address available in pointer
cout << "Value of *ip variable: ";
cout << *ip << endl;
return 0;
}
67
Output:
Value of var variable: 20
Address stored in ip variable: 0xbfc601ac
Value of *ip variable: 20

Pointers and Arrays
#include <iostream>
int main()
{
//Pointer declaration
int *p;
//Array declaration
int arr[]={1, 2, 3, 4, 5, 6};
//Assignment
p = arr;
for(int i=0; i<6;i++)
{
cout<<*p<<endl;
//++ moves the pointer to next int position
p++;
}
return 0;
}
68
OUTPUT:
0
1
2
3
4
5
6

this Pointers
• this pointer hold the address of current object
• int num;
• This->num=num;
69

this Pointers Example
#include <iostream>
class Employee
{
int id; //data member (also instance variable)
char name[20]; //data member(also instance variable)
float salary;
public:
Employee(int id, string name, float salary)
{
this->id = id;
this->name = name;
this->salary = salary;
}
void display()
{
cout<<id<<" "<<name<<" "<<salary<<endl;
}
}; 70
int main(void)
{
Employee e1 =Employee(101, "Sonoo", 890000);
//creating an object of Employee
Employee e2=Employee(102, "Nakul", 59000);
//creating an object of Employee
e1.display(); e2.display(); return 0;
}
Output:
101 Sonoo 890000
102 Nakul 59000

Function using pointers
71
#include<iostream>
void swap(int *a ,int *b );
//Call By Reference
int main()
{
int p,q;
cout<<"nEnter Two Number You Want To Swap n";
cin>>p>>q;
swap(&p,&q);
cout<<"nAfter Swapping Numbers Are Given belownn";
cout<<p<<" "<<q<<" n";
return 0;
}
void swap(int *a,int *b)
{
int c;
c=*a;
*a=*b;
*b=c;
}
Output:
Enter Two Number You Want to Swap
10 20
After Swapping Numbers Are Given below
20 10

MCQ
72
What will happen in the following C++ code snippet?
1)Int a=100, b=200;
2) Int *p=&a, *q=&b;
3) p=q;
Choose the correct one.
a) b is assigned to a
b) p now points to b
c) a is assigned to b
d) q now points to a

MCQ
73
a) b is assigned to a
b) p now points to b
c) a is assigned to b
d) q now points to a

MCQ
74
What is output of the following code?
#include <iostream>
int main()
{
char arr[20];
int i;
for(i = 0; i < 10; i++)
*(arr + i) = 65 + i;
*(arr + i) = '0';
cout << arr;
return(0);
}

MCQ
75
Answer: ABCDEFGHIJ
Explanation:
• Each time we are assigning 65 + i.
• In first iteration i = 0 and 65 is assigned.
• So it will print from A to J.

SESSION-03
Type Conversions,
Conditional and Looping Statements

Type Conversions
• Type conversion is the process that converts the predefined data type of
one variable into an appropriate data type.
• Type conversion can be done in two ways in C++
1. Implicit type conversion
2. Explicit type conversion
77

Implicit Type Conversions
• The type conversion that is done automatically done by the compiler
• This type of conversion is also known as automatic conversion
#include <iostream>
int main ()
{
// assign the integer value
int num1 = 25;
// declare a float variable
float num2;
// convert int value into float variable using implicit conversion
num2 = num1;
cout << " The value of num1 is: " << num1 << endl;
cout << " The value of num2 is: " << num2 << endl;
return 0;
}
78
Output:
The value of num1 is: 25
The value of num2 is: 25

Explicit Type Conversions (or)
Type Casting
• Conversions that require user intervention to change the data type of one
variable to another
• Hence, it is also known as typecasting
• The explicit type conversion is done in two ways:
– Explicit conversion using the cast operator
– Explicit conversion using the assignment operator

1. Explicit conversion using the cast operator
#include <iostream>
int main ()
{
float f2 = 6.7;
// use cast operator to convert data from one type to another
int x = static_cast <int> (f2);
cout << " The value of x is: " << x;
return 0;
}

2. Explicit conversion using the assignment operator
#include <iostream>
int main ()
{
// declare a float variable
float num2;
// initialize an int variable
int num1 = 25;
// convert data type from int to float
num2 = (float) num1;
cout << " The value of int num1 is: " << num1 << endl;
cout << " The value of float num2 is: " << num2 << endl;
return 0;
}

Conditional and looping statements
• if…else
• switch
• for
• while
• do…while
• break
• continue
82

SESSION-04
Arrays - C++ 11 features

Arrays
• Declaring Arrays
type arrayName [ arraySize ];
• Initializing Arrays
double balance[5] = {1000.0, 2.0, 3.4, 17.0, 50.0};
double balance[] = {1000.0, 2.0, 3.4, 17.0, 50.0};
balance[4] = 50.0;
• Accessing Array Elements
84

Accessing Array Elements
#include <iostream>
#include <iomanip>
using std::setw;
int main ()
{
int n[ 10 ]; // n is an array of 10 integers
// initialize elements of array n to 0
for ( int i = 0; i < 10; i++ )
{
n[ i ] = i + 100; // set element at location i to i + 100
}
cout << "Element" << setw( 13 ) << "Value" << endl;
// output each array element's value
for ( int j = 0; j < 10; j++ )
{
cout << setw( 7 )<< j << setw( 13 ) << n[ j ] << endl;
}
return 0;
}
85
Element Value
0 100
1 101
2 102
3 103
4 104
5 105
6 106
7 107
8 108
9 109

C++ version 11 features
• Simple and User Friendly
• Object Oriented Programming
• Platform Dependent
• Structured Programming Language
• Mid-Level Programming Language
• Rich Library
• Case-Sensitive
• Dynamic Memory Allocation
• Memory Management
• Powerful and Fast
86

SESSION-05
Class and Objects, Abstraction and
Encapsulation

CLASS AND OBJECTS, ABSTRACTION AND
ENCAPSULATION
88

Class
• Class is a user defined data type, defined using keywork class.
• It holds its own data members and member functions,
• It can be accessed and used by creating instance of that class.
• The variables inside class definition are called as data members and
the functions are called member functions
class className
{
data members
member functions
};

Syntax of Class
class ClassName
{
public:
// Member variables (attributes)
dataType memberVariable1;
dataType memberVariable2;
// ...
// Member functions (methods)
returnType methodName1(ParameterType1 parameter1, ParameterType2 parameter2)
{
// Function body
}
returnType methodName2(ParameterType3 parameter3)
{
// Function body
}
// ...
};
90

Class
• Class is just a blue print, which declares and defines
characteristics and behavior, namely data members
and member functions respectively.
• All objects of this class will share these characteristics
and behavior.
• Class name must start with an uppercase
letter(Although this is not mandatory).
Example,
class Student
91
Example
class Room
{
public:
double length;
double breadth;
double height;
double calculateArea()
{
return length * breadth;
}
double calculateVolume()
{
return length * breadth * height;
}
};

Define a class

Data Member
Data members Can be of any type, built-in or user-
defined.
This may be,
• non-static data member
Each class object has its own copy
• static data member
Acts as a global variable

Static Data Member
• Static data member is declared using the static keyword.
• There is only one copy of the static data member in the class. All the objects share
the static data member.
• The static data member is always initialized to zero when the first class object is
created.
Syntax:
static data_type datamember_name;
Here
static is the keyword.
data_type – int , float etc…
datamember_name – user defined Dr.M.Sivakumar, AP/NWC 94

Static Data Member
#include <iostream>
class Account
{
public:
int accno; //data member (also instance variable)
string name;
static int count;
Account(int accno, string name) // Constructor Function
{
this->accno = accno;
this->name = name;
count++;
}
void display()
{
cout<<accno<<" "<<name<<endl;
}
};
int Account::count=0;
int main(void)
{
Account a1 =Account(201, "Sanjay");
//creating an object of Account
Account a2=Account(202, "Nakul");
Account a3=Account(203, "Ranjana");
a1.display();
a2.display();
a3.display();
cout<<"Total Objects are: "<<Account::count;
return 0;
}
Output:
201 Sanjay
202 Nakul
203 Ranjana
Total Objects are: 3

Member Functions
• Used to
– access the values of the data members (accessor)
– perform operations on the data members (implementor)
• Are declared inside the class body
• Their definition can be placed
– inside the class body, or
– outside the class body
• Can access both public and private members of the class
• Can be referred to using dot or arrow member access operator

Member Functions
class Rectangle
{
private:
int width, length;
public:
void set (int w, int l);
int area()
{
return width*length;
}
};
void Rectangle :: set (int w, int l)
{
width = w;
length = l;
}
member function
keyword Class Name
inside the class
outside the class
class name
Member function
int main()
{
Rectangle r2;
r1.set(5,8);
int x=r1.area();
cout<<"x value in r1 "<<x;
r2.set(5,8);
int x=r1.area();
cout<<"x value in r2 "<<x;
}
Object
creation
Inside the
function
scope operator

const member function
• The const member functions are the functions which are declared as
constant in the program.
• The object called by these functions cannot be modified.
• It is recommended to use const keyword so that accidental changes to
object are avoided.
• A const member function can be called by any type of object.
• Note: Non-const functions can be called by non-const objects only.
Syntax:
datatype function_name() const
{
}

const member function
#include<iostream>
class sample
{
private:
int val;
public:
sample(int x = 0)
{
val = x;
}
int getValue() const
{
return val;
}
};
int main()
{
const sample s(20);
sample s1(2);
cout << "The value using object d : " << s.getValue();
cout << "nThe value using object d1 : " <<
s1.getValue();
return 0;
}

SESSION-06
Access Specifiers, Methods

Access Specifiers
• One of the main features of object-oriented programming languages
such as C++ is data hiding.
• Data hiding refers to restricting access to data members of a class.
• This is to prevent other functions and classes from tampering with
the class data.
Definition :
The access specifiers of C++ allows us to determine which class
members are accessible to other classes and functions, and which
are not.

Types of access specifiers
• Public members can be accessed from anywhere
in the program, including outside the class.
Public
• Private members can only be accessed from
within the class itself.
Private
• Protected members can be accessed from within
the class itself, from derived classes and from
friend function
Protected

Example: public
#include<iostream>
class student
{
public:
char name[20];
int age;
void display();
};
int main()
{
student s1;
cout<<"Enter name:";
cin>>s1.name;
cout<<"Enter age:";
cin>>s1.age;
s1.display();
return 0;
}
void student::display()
{
cout<<"Name:"<<name<<endl;
cout<<"Age:"<<age;
}
Output:
Enter name:raja
Enter age:20
Name:raja
Age:20

Example: private
#include<iostream>
class student
{
private:
char name[20];
int age;
public:
void getdata();
void display();
};
int main()
{
student s1;
//cin>>s1.name;
//cin>>s1.age;
s1.getdata();
s1.display();
return 0;
}
void student::getdata()
{
cin>>name;
cout<<"Enter age:";
cin>>age;
}
{
cout<<"Age:"<<age;
}
Output:
Enter name:raja
Enter age:21
Name:raja
Age:21

Example: protected
#include<iostream>
class person
{
protected:
char name[20];
int age;
};
class student: public person
{
public:
void getdata();
void display();
};
int main()
{
student s1;
s1.getdata();
s1.display();
return 0;
}
void student::getdata()
{
cin>>name;
cout<<"Enter age:";
cin>>age;
}
{
cout<<"Age:"<<age;
}
Output:
Enter name:raja
Enter age:22
Name:raja
Age:22

Syntax of Declaring Access Specifiers in C++
class ClassName
{
private:
// declare private members/methods here
public:
// declare public members/methods here
protected:
// declare protected members/methods here
};

Conclusion
• If any sensitive information that, when leaked or tampered with,
can cause trouble, always make sure to set the access
specifier as private.
• All other classes and functions can access public elements.
• Private elements cannot be accessed outside the class in which
they are declared.
• Private elements can be accessed outside the class in which they
are declared only when the class is a friend class or function is a
friend function of that class.

Conclusion
• Protected elements can be accessed by derived classes. They
are almost similar to the private access specifier.
• If we do not mention any access specifier for the members
inside the class, then by default, the Access Specifier in C++ for
the members will be Private.
• All functions are accessible to the friend function of the class.
Access Specifier Same Class Outside Class Derived Class
Public Modifier YES YES YES
Private Modifier YES NO NO
Protected Modifier YES NO YES

SESSION-07
UML Diagrams Introduction – Use Case Diagram, Class Diagrams

UML Diagrams Introduction
• UML, or Unified Modeling Language, is a standardized
modeling language used in software engineering for
visualizing, specifying, constructing, and documenting
software systems.
• There are several types of UML diagrams, each serving a
specific purpose in the software development process.
110

Why we use UML?
• Use graphical notation: more clearly than natural language
(imprecise) and code (too detailed).
• Help acquire an overall view of a system.
• UML is not dependent on any one language or technology.
• UML moves us from fragmentation to standardization.
111

Types of UML Diagrams
• Use case Diagrams
– Describe the functional behavior of the system as seen by the user.
• Class diagrams
– Describe the static structure of the system: Objects, Attributes,
Associations
• Sequence diagrams
– Describe the dynamic behavior between actors and the system and
between objects of the system
• Statechart diagrams
– Describe the dynamic behavior of an individual object (essentially a
finite state automaton)
• Activity Diagrams
– Model the dynamic behavior of a system, in particular the workflow
(essentially a flowchart)
112

Use Case Diagram
113

Use Case Diagram
114

Class Diagram
• It is the most common diagram type for software documentation
• Class diagrams contain classes with their attributes (data members) and
their behaviours (member functions)
• A class is a rectangle divided into three parts
– Class name
– Class attributes (i.e. data members, variables)
– Class operations (i.e. methods)
• The relation between different classes makes up a class diagram
• Modifiers
– Private: -
– Public: +
– Protected: #
– Static: Underlined
(i.e. shared among all members
of the class)
115
ClassName
Attributes
Behaviours
+getName() : string
+setName()
-calcInternalStuff(in x : byte, in y : decimal)
-Name : string
+ID : long
#Salary : double
Employee

Class Diagram
• It is the most common diagram type for software documentation
• Class diagrams contain classes with their attributes (data members) and their
behaviours (member functions)
• A class is a rectangle divided into three parts
– Class name
– Class attributes (i.e. data members, variables)
– Class operations (i.e. methods)
• The relation between different classes makes up
a class diagram
116
ClassName
Attributes
Behaviours
+getName() : string
+setName()
-calcInternalStuff(in x : byte, in y : decimal)
-Name : string
+ID : long
#Salary : double
Employee

Class Diagram Example
117
Account_Name
- Customer_Name
- Balance
+addFunds( )
+withDraw( )
+transfer( )
Name
Attributes
Operations

Class Diagram Example
118

Basic components of a class diagram
119
The standard class diagram is composed of three sections:
• Upper section: Contains the name of the class. This section is
always required, to know whether it represents the classifier or
an object.
• Middle section: Contains the attributes of the class. Use this
section to describe the qualities of the class. This is only required
when describing a specific instance of a class.
• Bottom section: Includes class operations (methods). Displayed in
list format, each operation takes up its own line. The operations
describe how a class interacts with data.
Class Name
Attributes
Behaviors

RULES TO BE FOLLOWED
120
• Class name must be unique to its enclosing namespace.
• The class name begins in uppercase and the space between
multiple words is omitted.
• The first letter of the attribute and operation names is lowercase
with subsequent words starting in uppercase and spaces are
omitted.
• Since the class is the namespace for its attributes and operations
an attribute name must be unambiguous in the context of the class.

Attributes : Second Section
121
• How would you identify each instance of that class, i.e., a specific animal?
• Using Attributes
• What are Attributes?
• A significant piece of data containing values that describe each instance of that class
• They are also known as fields, variables or properties
• Format for specifying an attribute:
visibility attributeName : Type [multiplicity] = DefaultValue {property string}
• Visibility: It sets the accessibility of an attribute / method
• Private (-) Visible only to the elements within the same class
• Public (+) Visible to any element that can see the class
• Protected (#) Visible to the elements in the class and its sub class
• Package (~) Visible to elements within the same package

Methods : Third section
122
• They are also known as operations or functions
• It specifies the behaviour of a class
• Eg: We may want to change the name of an Animal
• We could add a method setName
• We could also create a method for eating, since all of our animals eat
• Lets take another example : Employee Details

Relationships
123

Relationships
• Association: Represents a relationship between two classes, indicating that
objects of one class are connected to objects of another class.
• Inheritance/Generalization: Represents an "is-a" relationship, where one class
(subclass) inherits attributes and operations from another class (superclass). It is
depicted with a solid line and an arrowhead pointing to the superclass.
• Dependencies: Indicates that one class depends on another class, typically in
terms of method parameters or return types. Dependencies are represented with
a dashed arrow.
• Aggregation: Represents a "whole-part" relationship, where one class is
composed of one or more instances of another class. It is depicted with a hollow
diamond at the aggregate end.
• Composition: Similar to aggregation but with stronger ownership semantics. It
indicates that the "part" class is entirely dependent on the "whole" class and has
no independent existence. Composition is denoted with a filled diamond at the
composite end.
• Multiplicity: Specifies how many instances of one class are related to instances of
another class. It is denoted using numbers or ranges.

SESSION-08

Practice questions
• Define a class BankAccount with attributes such as account
number, account holder name, and balance. Implement methods
to deposit money, withdraw money, and display account
information.
• Create a class Student with attributes like roll number, name,
marks in different subjects, etc. Implement methods to calculate
total marks, average marks, and display student information.
• Define a class vehicle with attributes like the vehicle's registration
number, make, model, year of manufacture, and current mileage.
Implement methods for setting and getting these attributes
• Define a book and contain attributes such as title, author, ISBN,
genre, and availability status. It should have methods for setting
and getting these attributes.

SESSION-09

Quiz/Puzzles/Review
Questions

END
129

Object Oriented Design and Programming Unit-01

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