Object Oriented Programming With C++

26-07-2018 08:24:48 PM
vishnuvishnushaji5@gmail.com [1/38]
OBJECT-ORIENTED PROGRAMMING WITH C++
OBJECT-ORIENTED
PROGRAMMING WITH C++
VISHNU P S

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Procedure Oriented Programming Object Oriented Programming
Divided Into In POP, program is divided into small parts
called functions.
In OOP, program is divided into parts called
objects.
Importance In POP, Importance is not given to data but
to functions as well as sequence of actions
to be done.
In OOP, Importance is given to the data
rather than procedures or functions because
it works as a real world.
Approach POP follows Top Down approach. OOP follows Bottom Up approach.
Access Specifiers POP does not have any access specifier. OOP has access specifiers named Public,
Private, Protected, etc.
Data Moving In POP, Data can move freely from
function to function in the system.
In OOP, objects can move and communicate
with each other through member functions.
Expansion To add new data and function in POP is
not so easy.
OOP provides an easy way to add new data
and function.

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Contd…
Overloading In POP, Overloading is not possible. In OOP, overloading is possible in the form of
Function Overloading and Operator
Overloading.
Examples Example of POP are : C, VB, FORTRAN,
Pascal.
Example of OOP are : C++, JAVA, VB.NET,
C#.NET
Data Access In POP, Most function uses Global data for
sharing that can be accessed freely from
function to function in the system.
In OOP, data can not move easily from
function to function,it can be kept public or
private so we can control the access of data.
Data Hiding POP does not have any proper way for
hiding data so it is less secure.
OOP provides Data Hiding so provides more
security.

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BASIC CONCEPTS OF OBJECT-ORIENTED PROGTAMMING
OBJECTS CLASSES
DATA
ABSTRACTION
DATA
ENCAPSULATION
INHERITANCE POLIYMORPHISM
DYNAMIC
BINDING
MESSAGE
PASSING

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#include<iostream.h>
main()
{
cout<<“Hello World!”;
return 0;
}
#include<stdio.h>
int main()
{
printf(“Hello World!”);
return 0;
}

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MEMMORY ALLOCATION
STATIC DYNAMIC
 is allocated at the start of your
program
 the global variables or global
available arrays
 is allocated at runtime
 malloc(), calloc(), new

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C
•malloc()
•calloc()
C++
•new

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new
 C++ uses new operator to allocate memory dynamically at run time.
Syntax
pointer_variable = new data_type;
Example
int *p;
p = new int;
int *q = new int;

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delete
 Destroyed by using delete.
Syntax
delete pointer_variable;
Example
delete p;
delete q;

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CLASSES AND OBJECTS
CLASS OBJECT
 It is a user defined data type
 which holds its own data members
and member functions
 which can be accessed and used by
creating an instance of that class
 A class is like a blueprint for an
object.
is an instance of a Class.
When a class is defined, no memory is
allocated but when it is instantiated
(i.e. an object is created) memory is
allocated.

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DEFINING CLASS

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DECLARING OBJECTS
When a class is defined, only the specification for the object is
defined; no memory or storage is allocated. To use the data and
access functions defined in the class, you need to create objects.
ClassName ObjectName;

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ACCESSING DATA MEMBERS AND MEMBER FUNCTIONS
ACCESSING DATA MEMBERS
The data members and member functions of class can be accessed using the dot(‘.’)
operator with the object. For example if the name of object is obj and you want to access
the member function with the name printName() then you will have to write
obj.printName() .
The public data members are also accessed in the same way given however the private data members
are not allowed to be accessed directly by the object. Accessing a data member depends solely on the
access control of that data member.

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// C++ program to demonstrate
// accessing of data members
#include <bits/stdc++.h>
using namespace std;
class Geeks
{
// Access specifier
public:
// Data Members
string name;
// Member Functions()
void printname()
{
cout << “Name is: " << name;
}
};
int main() {
// Declare an object of class
geeks
Geeks obj1;
// accessing data member
obj1.name = "Abhi";
// accessing member function
obj1.printname();
return 0;
}

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The capability of a class to derive properties
and characteristics from another class is
called Inheritance. Inheritance is one of the
most important feature of Object Oriented
Programming.
INHERITANCE IN C++
Sub Class :
The class that inherits properties from
another class is called Sub class or
Derived Class.
Super Class :
The class whose properties are inherited
by sub class is called Base Class or Super
class.

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Why and when to use inheritance?

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Implementing inheritance in C++
For creating a sub-class which is inherited from the base class we have to follow the below
syntax.
class subclass_name : access_mode base_class_name
{
//body of subclass
};
subclass_name is the name of the sub class, access_mode is the mode in which you
want to inherit this sub class for example: public, private etc. and base_class_name is
the name of the base class from which you want to inherit the sub class.

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// C++ program to demonstrate
implementation
// of Inheritance
#include <iostream.h>
//Base class
class Parent
{
public:
int id_p;
};
// Sub class inheriting from Base
Class(Parent)
class Child : public Parent
{
public:
int id_c;
};
//main function
int main()
{
Child obj1;
// An object of class child has
all data members
// and member functions of class
parent
obj1.id_c = 7;
obj1.id_p = 91;
cout << "Child id is "
<< obj1.id_c << endl;
cout << "Parent id is "
<< obj1.id_p << endl;
return 0;
}

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Modes of Inheritance
Public mode:
If we derive a sub class from a public
base class. Then the public member
of the base class will become public
in the derived class and protected
members of the base class will
become protected in derived class.
Private members of the base class
will never get inherited in sub class.
Protected mode:
If we derive a sub class from a
Protected base class. Then both
public member and protected
members of the base class will
become protected in derived class.
Private members of the base class
will never get inherited in sub class.
Private mode:
If we derive a sub class from a
Private base class. Then both public
member and protected members of
the base class will become Private in
derived class. Private members of
the base class will never get
inherited in sub class.

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The below table summarizes the above three modes and shows the access specifier of the members of base
class in the sub class when derived in public, protected and private modes:

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TYPES OF INHERITANCE IN C++
Single Inheritance Multiple Inheritance
Multilevel Inheritance Hierarchical Inheritance
Hybrid (Virtual) Inheritance

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Single Inheritance
In single inheritance, a class is allowed to inherit from only one class. i.e.
one sub class is inherited by one base class only.

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Multiple Inheritance
Multiple Inheritance is a feature of C++ where a class can inherit from more
than one classes. i.e one sub class is inherited from more than one base
classes.

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Multilevel Inheritance
In this type of inheritance, a derived class is created from another derived
class.

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Hierarchical Inheritance
In this type of inheritance, more than one sub class is inherited from a
single base class. i.e. more than one derived class is created from a single
base class.

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Hybrid (Virtual) Inheritance
Hybrid Inheritance is implemented by combining more than one type of
inheritance. For example: Combining Hierarchical inheritance and Multiple
Inheritance.

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DYNAMIC BINDING
• THE COMPILER MATCHES THE FUNCTION CALL WITH THE CORRECT
FUNCTION DEFINITION AT RUNTIME. IT IS ALSO KNOWN AS LATE BINDING
OR RUNTIME BINDING.
• IN LATE BINDING, THE COMPILER IDENTIFIES THE TYPE OF OBJECT AT
RUNTIME AND THEN MATCHES THE FUNCTION CALL WITH THE CORRECT
FUNCTION DEFINITION.
• THIS CAN BE ACHIEVED BY DECLARING A VIRTUAL FUNCTION.

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#include <iostream>
class Animals
{
public:
void sound()
{
cout << "This is parent class" <<
endl;
}
};
class Dogs : public Animals
{
public:
void sound()
{
cout << "Dogs bark" << endl;
}
};
int main()
{
Animals *a;
Dogs d;
a= &d;
a -> sound(); // early binding
return 0;
}

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FRIEND CLASS
A friend class can access private and protected members of other class in which it is
declared as friend. It is sometimes useful to allow a particular class to access private
members of other class. For example a LinkedList class may be allowed to access private
members of Node.
FRIEND FUNCTION
Like friend class, a friend function can be given special grant to access private and
protected members. A friend function can be:
a) A method of another class
b) A global function

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class Node
{
private:
int key;
Node *next;
/* Other members of Node Class */
friend class LinkedList; // Now class
LinkedList can
// access
private members of Node
}
class Node
{
private:
int key;
Node *next;
/* Other members of Node Class */
friend int LinkedList::search(); // Only
search() of linkedList
// can
access internal members
};
FRIEND CLASS FRIEND FUNCTION

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ENCAPSULATION IN C++
Encapsulation is defined as wrapping up of data and information under a single unit
(Encapsulation is defined as binding together the data and the functions that manipulates
them.)
Consider a real life example of encapsulation, in a company there
are different sections like the accounts section, finance section,
sales section etc. The finance section handles all the financial
transactions and keep records of all the data related to finance.
Similarly the sales section handles all the sales related activities
and keep records of all the sales. Now there may arise a situation
when for some reason an official from finance section needs all the
data about sales in a particular month. In this case, he is not
allowed to directly access the data of sales section. He will first
have to contact some other officer in the sales section and then
request him to give the particular data. This is what encapsulation
is. Here the data of sales section and the employees that can
manipulate them are wrapped under a single name “sales section”.

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TEMPLATES IN C++

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TEMPLATES IN C++
 Template is simple and yet very powerful tool in C++.
 The simple idea is to pass data type as a parameter so that we don’t need to write same
code for different data types.
 For example a software company may need sort() for different data types. Rather than
writing and maintaining the multiple codes, we can write one sort() and pass data type as a
parameter.
C++ adds two new keywords to support templates: ‘template’
CLASS TEMPLATES
FUNCTION TEMPLATES

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How templates work?
Templates are expended at compiler time.
This is like macros. The difference is, compiler
does type checking before template
expansion. The idea is simple, source code
contains only function/class, but compiled
code may contain multiple copies of same
function/class.

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C++ Exception Handling
 An exception is a problem that arises during the execution of a program.
 A C++ exception is a response to an exceptional circumstance that arises while a
program is running, such as an attempt to divide by zero.
 Exceptions provide a way to transfer control from one part of a program to another.
 C++ exception handling is built upon three keywords: try, catch, and throw.

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 throw − A program throws an exception when a problem shows up. This is done using
a throw keyword.
 catch − A program catches an exception with an exception handler at the place in a
program where you want to handle the problem. The catch keyword indicates the
catching of an exception.
 try − A try block identifies a block of code for which particular exceptions will be
activated. It's followed by one or more catch blocks.

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REFERENCE
https://www.tutorialspoint.com/
https://www.geeksforgeeks.org/
https://en.wikipedia.org/wiki/Main_Page

Object Oriented Programming With C++

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