Introduction to oop

CENTRE FOR INFORMATION
TECHNOOLGY,UPES ,DEHRADUN
• Name of the staff

: VENKATADRI.M.

• Designation

:Asst Prof (SS).

• Branch

: Computer Science and Engineering.

• Institute

: University Of Petroleum and Energy
Studies

• Semester

: III

• Subject

: OOPS With C++

• Subject Code

:.

• Topic

: Understand the concept of OOP
methodology

•Teaching aids used

: Diagrams, animations, PPT

Objective
On completion of this period, you would be
able to know
• Evolution of OOPS( Object Oriented
Programming )
• History of C++

Venkatadri.M,Asst Prof
(SS).UPES,Dehradun

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RECAP
• Do you know about C language ?

• It is based on what program design ?
• Is it Procedure / Object oriented ?

(SS).UPES,Dehradun

Appreciate the evolution of OOP
• OOPs was evolved to overcome the drawbacks
of conventional programming methods.
• It allows dividing a problem into no.of entities
called as Objects.
• OOP treats data as a critical element in the
program.

(SS).UPES,Dehradun

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Appreciate the evolution of OOP

• It does not allow the data to flow freely around the
system.
• It hides the data.
• It provides security to the data.

(SS).UPES,Dehradun

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Organization of data & functions in
OOPS
Object A

Object B

Data
Functions
Communication

Data
communication

Functions

Object C

Communication

Data
Functions

Fig 1.1

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History of C++
•

C++ was developed by Bjarne Stroustrup at
Bell Labs in USA.

• It was initially called as “C with Classes”.
• It is super set of ‘C’ language.

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History of C++
•It follows bottom-up program design.
• Objects will communicate with each other.
• Objects are independent.
• It binds the data and functions together.
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Summary
In this class , you have learnt …
• Evolution of OOPS

• History of C++

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Frequently Asked Questions

1. Explain the Evolution of OOPS.
2. Explain the History of C++.

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Quiz
1. OOPS was developed by________________.

(SS).UPES,Dehradun

Quiz
1. OOPS was developed by Bjarne Stroustrup

(SS).UPES,Dehradun

Quiz
2. C++ is __________________ Programming
language.

(SS).UPES,Dehradun

Quiz
2. C++ is Object Oriented Programming
language.

(SS).UPES,Dehradun

Quiz
3.

C++ is based on___________________.

(SS).UPES,Dehradun

Quiz
3.

C++ is based on Objects.

(SS).UPES,Dehradun

Quiz
4. C++ provides _________________to the data.

(SS).UPES,Dehradun

Quiz
4.

C++ provides Security to the data.

(SS).UPES,Dehradun

Quiz
5. OOPS is _______________ programming
design.

(SS).UPES,Dehradun

Quiz
5.

OOPS is Bottom up programming design.

(SS).UPES,Dehradun

Procedure Oriented Programming (POP)

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Limitations of POP
• Emphasis is on algorithm or procedure

• Not suitable for modeling a real world problem
• No security & integrity to the data
• Data can’t be hidden
• Inheritance & Polymorphism are difficult to achieve
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Limitations of POP
• Follows top down program design
• Can’t reuse the existing code
• Data will be shared by many functions
• Difficult to write and understand
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Organization of data & functions in
OOPS
Object A

Object B

Data
Functions
Communication

Data
communication

Object C

Functions
Communication

Data
Functions

Fig 2.2

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Features of Object Oriented Languages
• Emphasis is on data rather than the procedure

• Both data and functions are combined into a
single unit
• Data can’t be accesssed directly

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• Data is hidden and can’t be accessed by external
functions
• Programs are divided into elements known as
objects
• Objects may communicate with each other
through functions
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• New data and functions can be easily added

• Follows bottom up approach of program design
• We can eliminate the redundant code
• Time will be saved

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Features of Object Oriented Language
• Higher productivity
• Provides multiple instances of an object
• Provides security to the data
• Easy to write and understand a program
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• Data is critical element.

• Data can not be freely accessed by extenal functions
• Permits reusability of the existing code

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Languages that support OOPs

• C++
• Small talk
• Java
• Simula etc

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Features of Object Oriented Language
• We can easily upgrade from small to large systems
• We can build user defined data types
• Objects are to classes as variables are to data types

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Applications of OOPS
• Artificial Intelligence & Expert systems

• Simulation & modeling
• OO databases
• Hypertext, Hyper media and Expertext
• CAD / CAM / CAE
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Applications of OOPS
•Decision support system
• Neural Networks
• Real time systems
• Multimedia applications
• GUI, CBTs, Office automation etc
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Properties of oops
•
•
•
•
•
•

Object
Class
Encapsulation
Data abstraction
Inheritence
Polymorphism

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Objects
• Objects are the basic run time entities.

• Can be defined as an identifiable entity
with characteristics and behavior.
• We are often surrounded by variety of
objects like
• computer
• chair
• telephone etc.,
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Characteristics of Object

• State
• Behavior
• Identity

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Characteristics of Object
Example:Consider the object telephone it has
• a set of attributes like color, shape, and model
etc.,
• Behaviour is that it announces a call.
• Identity is the unique telephone number.
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Object communication
• Objects interact with each other by sending
messages to each other.
• It occupies space in memory.
• Each object is having its own address.

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• Each object contains data and some code to
manipulate the data.
• for example
Object: Student
DATA:
Name
Marks
FUNCTIONS:
Total
Average

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• Objects have life cycle.

• They can be created and destroyed.
• Communication with an object is feasible as long
as it is alive.

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Classes
• It is defined as a collection of objects of similar type.

• The set of data and code of an object can be made a
user defined data type using a class.
• In fact objects are variables of type class.
• We can create any number of objects belonging to
that defined class.
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Classes
Example:banana, apple and mango are the examples of
members of class of fruit.
• If fruit is defined as class then
Fruit mango;
Will create an object mango belonging to the
class fruit.
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Encapsulation
• The wrapping up of data and functions into single

unit is known as ‘ENCAPSULATION’.
• The data is not accessible to outside world.
• Only the member functions within the class can
access the data.
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Encapsulation
•These functions provide an interface between the
object’s data and the program.
• This insulation of data from direct access by the
program is called data hiding.

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Data Abstraction
• Abstraction refers to the representation of essential

features without including background details or
explanations.
• Since the classes use data abstraction they are
also known as Abstract Data Type (ADT).

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Inheritance
• It is the process of creating a new class from
the existing class.
• The new class inherits all the characteristics of
the existing class.
• It is like a hierarchical classification.

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Inheritance
• We can add additional features to an existing
class without modifying it. This is known as
reusability.
• Each derived class shares common
characteristics with the class from which it is
derived.
• The new class will have combined features of
both the classes.
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Polymorphism
• The ability to take more than one form.
• An operation may exhibit different behaviours in
different instances.
• The behaviour depends upon the types of data
used in the operation.
• Polymorphism is used extensively in
implementing the inheritance.
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Polymorphism-Example

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Polymorphism-operator over loading
•Consider the operation of addition.
• For two numbers it generates a sum.
• If the operands are string then the operation
would produce a third string by concatenation.

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Polymorphism-operator over loading
•The process of making an operator to exhibit
different behaviours in different instances is
known as operator overloading.
• A single function name can be use to handle
different members and different types of
arguments.
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Polymorphism – function overloading
• It is nothing but a particular word in having several

different meanings depending on the context.
• Using a single function name to perform different
types of tasks is known as function overloading.

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Dynamic binding

• It is also known as late binding.

• The code associated with a given procedure is
not known until the time of call at run time.

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Objective
The end of the class you would be able to
learn…
• Creating a C++ program
• Compiling & linking it
• Running

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RECAP
• What is a program?

• How to create a program in C ?
• What is a compiler ?

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Program development & execution

Fig 4.1
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Creating a C++ program
• Turbo C++ provides a powerful environment called

IDE for creating and executing a C++ program.
• The IDE is completely menu-driven and allows the
user to create, edit, compile and run programs using
dialogue boxes.

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Creating a C++ program
• We first use the editor to create the C++ source
code file.
• When we invoke TURBO C++, we get the IDE
screen.
• It contains 4 parts as shown in fig B.2 in the next
slide

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TURBO C++ - IDE
• Now we can create and save a program in C++

• The F10 key will take you to main menu
• Now select the File option
• We have options like new, open, save etc
• Select the new option from file menu
• We get a blank window called as editing window
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TURBO C++ - IDE
• Now the system is ready to receive the program

statements
• After typing the program save the program in a file
• We can also save a program by pressing F2 key
• File name should have the extension .CPP
Ex :• test.cpp is the name of the C++ file
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Compiling a C++ program
• We can compile a program by choosing the

compile option on the main menu
• We get a compile dialogue window
• Select the option compile
• We get test.obj file after the compilation
•
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Compiling a C++ program
• During compilation we get a compilation window
• If there are no errors this window will display a
message as “ Success: Press any key” as shown
in the fig 4.3 in the next slide
• We can also compile a program by pressing F9
key
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TURBO C++ - Compilation screen

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Linking

• To link the object file test.obj with the standard

library functions, select the link option from the
compile menu
• We get a third file test.exe after linking

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Running the program
• To run a program select the Run option from the
main menu
• We can also run a program by pressing (Ctrl + F9)
key
• We get the output on the screen
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Objective

On completion of this period, you would be able to
know
• Structure of C++ program.

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Recap
In the previous class, we have discussed about
Difference between c & c++

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Structure of C++
• The C++ program contains four sections as shown
in figure 6.1.
• These sections may be placed in separate code
files and then compiled independently or jointly .

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Structure of C++ program :
Include files
Class declaration

Class functions
Definitions
main function
program

Fig 6.1
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Structure of C++ program
• We can organize a program into three separate
files.
• The class declarations are placed in a header
file.
• The definitions of member functions go into
another file.
• The main program that uses the class is placed
in third file which includes the previous two files
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Structure of C++
• This approach enables the programmer to
separate the abstract specification of the
interface( class definition) from the
implementation details (member functions
definitions).

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Structure of C++
• This approach is based on the concept of client
–server model as shown in fig.
Member functions
Server

Class definition

Main function program
Client

Fig 6.2: Client-server model.
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Structure of C++
• The class definition including the member functions
constitute the server.
• The server that provides services to the main
program known as the client.
• The client uses the server through the public
interface of the class.

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•

An example program with class.

#include<iostream.h> //Include files
class person
{
char name[30];
int age ;
public:
void get data(void);
void display(void);
};
void person::getdata(void)
{
cout<<“Enter name:”;
cin>>name;
cout<<“Enter age:”;
cin>>age;
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}

// class declaration

.
//class function definition

76

[contd….]

• An example program with class.
void person::display(void)
{
cout<<“n name:”<<name;
function definition
cout<<“age:”<<age;
}
main()

// class

{
person p;
p.getdata();
function program
p.display();
}

// main
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Objective
learn….
• Input operators
• Output operators
• Examples

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Cin & Cout
• C++ input/output resolves around the motion of a
data stream.
• We can insert data into an output stream or
extract data from an input stream.
• The standard output stream to the screen is
referred to as “cout”.
• The standard input stream from the keyboard is
referred to as cin.
• We can also cascade the I/O operators
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Cin – Input from the Keyboard:
•
•
•
•

cin stands for console in
It is used to accept input data from keyboard.
It can read only one word at a time
It is also known as extraction / get from operator
syntax :- cin>>variable name;
Ex:- cin>>x1>>x2;
We obtain input from the keyboard through the
stream cin ,using the extraction operator >> .
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Example
To read two integer values from the keyboard
into integer variables num1 and num2, we can
write as follows:
Cin>>num1>>num2;

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Example :
Contd..
Object
Cin

Keyboard

Extraction Operator

>>

Variable
45.5

Fig 7.1 :- Input using extraction operator
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Description :
• “>>” this operator is known as extraction
operator.

• The operation will be in the direction of the
data flow.
• The input statement executes from left to right.
• It extracts the value from the keyboard and
assigns it to the variable on its right.
• We can overload this operator
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Description (contd..):
• Floating point values are read from the
keyboard in exactly the same way as integers.
• We can also mix the two.
• The stream input and operations automatically
deal with variables and any data type.

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For exmple, look at the statements:
int num1=0,num2=0;
double factor=0.0;
cin>>num1>>factor>>num2;
The last line will read an integer into num1,
then a floating point value into factor and finally
an integer into num2.
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Cout – Output to the display :
• Cout is a predefined object that represents the
standard output stream in C++.
• The standard output stream is screen
• It is also possible to redirect the o/p to other
o/p devices
• It is reverse of cin .
• The operator “<<“ is also called as insertion /
put to operator
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Screen

Cout

Object

<<
Insertion Operator

“C++”

Variable

Fig 7.2 :- Output using insertion operator
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Description :
syn:- cout<<variable name;
Ex:- cout<<x1<<x2;
If x1= 1234 & x2= 5678 ,then output
will be “12345678”.

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• The object cout has a simple interface.
• It inserts the contents of the variable on its right
to the object on its left.
• If name represents a string variable, then the
following statement will display its contents:
cout << name;
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• We can also use this operator for overloading
• This concept is known as Operator
Overloading, an important aspect of
polymorphism.
• We can also use printf() statement in C++

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Manipulator
• These are the operators that are used to format
the data display.
• These are defined in the header file iomanip.h
• The most commonly used manipulators are
setw & endl

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Set width or setw(n)
Definition :
It is an io manipulator which will
output the value right justified in a ‘n’ spaces
wide.
syn:- setw(n);
Ex:- cout<<setw(6)<<x1<<setw(7)<<x2;

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Escape sequence
Definition :
These are the execution character set
& starts with a ‘’ character set.
For ex:- cout <<endl<<“Hello”;
cout<<endl<<“t Hello”;
Output :

Hello
Hello

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OBJECTIVES

learn…
• Comment statements in C
• Comment statement in C++
• Keywords of C++ other than C

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RECAP
• What is meant by comment ?
• What is keyword ?
• List keywords in C ?

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Comments in C++
• A comment is used for the documentation purpose.
• Comment starts with a double slash symbol(//) and
terminates at the end of the line.
• It may start any where in the line.
• There is no closing for a comment.
•

Comments are not executable.

• All comments are ignored by the compiler.

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Comments in C++
There are two ways of writing a comment.
• Single line comment.
Eg:- // write a program to add two numbers.

• Multi line comment.
Eg:- /* write a program
• to add two
• numbers */

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Comment statements in C
• C programmers are familiar with the /*..*/
style of commenting.
• Anything lying within the /*..*/ pair is ignored
by the compiler.
•

Eg:-/*This is the program*/

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Comment statements in C++

For example:
//This is an example
//of C++ program
/* This is an example of C program */

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Comment statements in C
NOTE:
•

You should always comment your
programs comprehensively.

•

The comment should be sufficient for any
programmer.

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Keyword
• Keyword or Reserved word is an identifier.

• It is pre-defined to the compiler.
• Keyword can’t be used for naming a variable in
programming.

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Keywords of C++ other than C
•
•
•
•
•
•
•
•

•
•
•
•
•
•
•
•

class
delete
friend
public
catch
new
template
operator
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try
throw
private
protected
inline
asm
this
virtual

103

• class:
It is an improvement over structure of c
conceptually, class is a way to bind data and its
associated functions together.

• delete:
Delete object pointed by a pointer must be used
on an object created by new operator.

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• friend:
A friend function declared as friend has access
to object of the class . It is not to member of any
class.

• public:
It is an access specifier.Members declared
public can be accessed freely in the program.
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• catch:
It catches and processes the exception.

• new:
It is an operator used for allocating memory
dynamically.

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• operator:
used in operator function to overload an
existing operator.

• template:
Constructs a family of related functions or
classes.They are sometimes called parameterized
classes.

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• try:
A block prefaced with keyword try can be throw an
exception.

• throw:
A mechanism for handling exceptions.

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• private:
It is an access specifier.Members declared private
can be accessed freely in the program.

• protected:
It is an access specifier.Members declared
protected can be accessed freely in the program.
However, such members can be directly inherited
directly in a derived class.

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• inline:
In C++ you can declare and define a member
function within its class such function is called inline.

 asm:
You use Asm statements to use assembly
language statements in the middle of your C++
source code.

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• this:
It is a pointer.When any object is
created, the system on its own sets a pointer
to that object.the name of the pointer variable
is ‘this’.
• virtual:
It can be used to make a class or
function virtual.
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Summary
• Comment statements in C
• Comment statements in C++
• Keywords of C++ other than C

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Any Questions….

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Frequently used Questions
1.

Define a comment?

2.

Explain the comment statements in C++?

3.

List the keywords of C++ other than C?

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Quiz
1. Comment start with a __________symbol.

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Quiz
1. Comment start with a Double slash symbol.

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Quiz
2. Catch is a keyword of________.

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Quiz
2. Catch is a keyword of C++.

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Quiz
3. There are ________ways of commenting in C+
+.

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Quiz
3. There are Two ways of commenting in C++.

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Introduction to oop

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