Programming Paradigms and OOP Features

• Programming Paradigms-monolithic, procedural, structured and object oriented ,
• Features of Object oriented programming:
• classes, objects, methods and message passing, inheritance, polymorphism,
containership, reusability, delegation, data abstraction and encapsulation
• Classes and Objects:
• classes and objects, class method and self object,
• class variables and object variables,
• public and private members, class methods.
Zeal College of Engineering and Research
UNIT: V Object Oriented Programming Lectures:
08 Hrs

 Programming paradigm is an approach to solve problem using
some programming language.
 There are lots for programming language that are known but all
of them need to follow some strategy when they are
implemented and this methodology/strategy is paradigms.
 Various programming paradigms are
1. Monolithic Programming
2. Procedural Programming
3. Structural Programming
4. Object Oriented Programming
Programming Paradigm:

1. Monolithic Programming:
 The Program which contains a single function for the large
program is called monolithic program.
 A program is not divided into parts
 When program size increases it also increase difficulty.
 The program is sequential code and variable used is global data.
 goto statement is used for specific jump or flow control
statement.

Advantages:
 Easy to implement programs for small applications.
Disadvantages:
 If the program size is large then it is difficult to check error.
 Due to single function, the program is difficult to maintain.
 Code cannot be reused as it is written for specific problem.

2. Procedural Programming
 Procedural programming is a programming paradigm that uses
a linear or top-down approach.
 It relies on functions (procedures or subroutines) to perform
computations.
 Procedural programming is also known as imperative
programming.
 Large programs are divided into smaller programs known as
functions.
 Function access the global data.
 Top down approach

Advantages:
Simple and easy to write.
These language have low memory utilization.
Disadvantages:
Parallel programming is not possible.
Difficult to maintain programs.
Less productive.

 Also known as modular programming.
 The structured program mainly consist of
1. Selection Statements (if, if…else, if….elif…else statements)
2. Sequence Statements
3. Iteration Statements (loops- for, while)
 The program consist of structured and separate modules.
 Example: C, Pascal
3. Structural Programming:

Advantages:
 Program is easy to implement and maintain.
 Programs are problem based not the machine based.
Disadvantages:
 Conversion of program to machine code takes time.
Savitribai Phule Pune University -2019-20

4. Object Oriented Programming:
 The program is written as a collection of classes and object
which are meant for communication.
 The smallest and basic entity is object and all kind of
computation is performed on the objects only.
 Data and function are grouped into one entity called class.
 Programs are divided into classes and member functions.

Advantages:
 Importance is given to data.
 Bottom up Approach
 Data is hidden and can not be accessed by external functions.
Disadvantages:
 Complex to implement.

Difference between procedure oriented language and object oriented language.
Sr
No.
Procedural Oriented
Language
Object oriented language
1
Importance is given to
algorithm
Importance is given to data
2 Top down appraoch Bottom Up Approach
3
Programs are divided into
functions
Programs are divided into objects
4 Data is not hidden
Data is hidden and can not be
accessed by external functions
5 no access specifier
private, public, protected access
specifier is used.
6 less secure more secure
7 Example: C, Pascal Example: C++, Java ,Python

Programming languages and the programming paradigms
they support.
C++ - Monolithic, Structured-oriented, Procedural-oriented and, Object-
oriented programming paradigm
Python - Object Oriented, Procedure, and Functional programming
paradigms
Java - Procedural and object oriented paradigm
JavaScript - functional, object-oriented, procedural, and prototypal
programming
C# - imperative, declarative, functional, generic, object-oriented (class-
based), and component-oriented
PHP - Procedural, Object-Oriented, and functional paradigm
Ruby - procedural, object-oriented, and functional programming
Visual Basic - object-oriented

Features of Object oriented programming:
1. Class:
 class is a collection of objects.
 It is a logical entity that has data members and methods
(member functions).
 Once class has been defined, we can create any number of
objects belonging to that class.
 Ex: Mango, Apple and Orange are the members of Fruit class.
Syntax:
class classname:
Ex:
class Fruit:

Syntax:
class classname:
statement 1 #Data members and Member functions
statement 2
statement 3
Ex:
class Student:
rollno = 101 # Data members
name = "Priya"
def fun(self):
print('Hello') # Member Functions

Class Method and self object:
 The class methods are the function defined inside the class.
 The class method defines the first argument as self. This is always
defined as the first argument.
 If there is no argument in class method then only self is the argument for
that method.
 The self argument refers to object itself.

2. Object:
 Object is an instance of class. The object is an entity that has state and
behavior.
 It may be any real-world object like the person, place, bank account or
any item etc.
 Everything in Python is an object.
Syntax:
objectname = classname( )
Ex:
obj = Fruit( )

Sr
No.
Class Object
1 Class is collection of
objects. Class is collection
of data members and
member functions.
An object is instance of a class.
2 Class is a logical entity. Object is a physical entity.
3 Class is declared once. Object is created many times.
4 Class doesn't allocated
memory when it is
created.
Object allocates memory when it
is created.
5
Ex: Class: Fruit
Ex: Object: Apple, Banana,
Mango, Guava

3. Method:
 The method is a function that is associated with an object.
 There must be a special first argument self in all of method definitions.
 Any object type can have methods.
 There is usually a special method called __init__ ( )in most classes.

Example
1. Write a python program to find area of rectangle using class.
class Rect:
def __init__(self,length,breadth):
self.length=length
self.breadth=breadth
def Area(self):
print("Area of rectangle is: ",r1.length*r1.breadth)
r1 = Rect(160,120)
r1.Area()
OUTPUT:
Area of rectangle is: 19200

4. Inheritance:
 Inheritance is the process by which object of one class acquires
properties object of another class.
 reusability concept is used.
 Sub Class: The class that inherits properties from another class is called
Sub class or Derived Class.
 Super Class/ Base class: The class whose properties are inherited by
sub class is called Base Class or Super class.
Example: Dog, Cat, Cow can be Derived Class of Animal Base Class.

Single Level Inheritance
class E:
def U_test_Marks(self):
print("Unit test marks submitted successfully")
def C_test_Marks(self):
print("Class test marks submitted successfully")
f1 = E()
f1.U_test_Marks()
f1.C_test_Marks()
class F(E):
pass
f2 = F()
f2.U_test_Marks()

5. Reusability:
 The child class inherits some behaviour of parent class.
 For child class, it is not necessary to write code for inherited behavior,
i.e. child class directly used the methods written in parent class.
 For instance, the class Student inherits Person class. Hence the method
such as getName( ), getAddress( ) of parent class Person can be
directly used by the Student class. The Student class can have its own
additional method such as getMarks( ).
 Thus methods can be written once and can be reused.

6. Polymorphism:
 Ability to perform more than one forms.
 An operation may exhibit different behaviors in different instances.
 The behavior depends upon the types of data used in the operation.
1. Operator Overloading
2. Method Overriding

Method Overriding
class E:
def name1(self,name):
print(name)
f1 = E()
f1.name1("punam")
class F:
def name1 (self,name):
print(name)
f2 = F()
f1. name1("punamsawale")

7. Containership:
 one class contain the object of another class.
 This type of relationship between classes is known as containership or
has a relationship.
 The class which contains the object and members of another class in this
kind of relationship is called a container class.
Ex: 1) computer system has a hard disk
2) car has an Engine, chassis, steering wheels.

8. Delegation:
 This is feature of object oriented programming by which one class
depends upon the other class.
 It is represented by has a relationship.
 In composition – The child cannot exist if parent class is not present i.e.
child class depends on parent class. It is strong relationship.
 In delegation there is dependency of one class on another but even if
the parent class is not present the dependent class exists.
 Ex: A teacher may belong to multiple departments. So, Teacher is a part
of multiple departments. But lets say if we “delete” a Department, the
Teacher will still be there. This is delegation.
 A school can contain multiple classrooms. Now if we “delete” the
school, the classrooms will automatically be deleted. This is
composition.

9. Data Abstraction and Encapsulation:
1. Data abstraction
 Data abstraction means representing only essential features by hiding all
the implementation details.
 Class is entity used for data abstraction.
 The methods are defined in class. From main function we can access
these functionalities using objects.
2. Encapsulation
 Encapsulation means binding of data and methods in single
entity called class.
 The data inside the class is accessible by the function in same class.
 Public and Private access specifier is used for data protection
 It is normally not accessible from outside of the component.

Sr
No.
Data abstraction Data encapsulation
1
Representing only essential
features by hiding all the
implementation details.
binding of data and methods in
single entity called class.
2
It is used in software design
phase.
It is used in software
implementation phase.
3
abstraction using Abstract
Class.
encapsulation using Access
Modifiers (Public, Protected &
Private.)
4
Depends on object data
type.
independent on object data type.
5
Focus mainly on what
should be done.
Focus primarily on how it should
be done.

Class Variables and object variables
1. Class variable
 The variables at the class level are called class variables.
 The class variables are shared by all the instances of the class i.e. same
value is used for every instance or object
 There is single copy of class variable which is shared among all the
objects, hence changes made by an object in a single copy of class
variable is reflected in all other objects.
2. Object Variable
 The variable owned by each object is called object variable.
 For each object or instance of class, the instance variables are different.
 Object variables are defined in methods.
 The changes made in one object variable will not be reflected for other
object variable.

class PPS:
Attendance = 0 #class variable
def __init__(self, var):
PPS.Attendance += 1
self.var = var #object variable
print("Lecture No: ", PPS.Attendance)
print("Total student present for lecture 1 : ", var)
obj1 = PPS(50)
obj2 = PPS(52)
obj3 = PPS(55)

Output:
Lecture No: 1
Total student present for lecture 1 : 50
Lecture No: 2
Lecture No: 3

Public and private members:
 Public variables are those variables that are defined in the class and can be
accessed from within class and from outside the class using dot operator.
 All members in a python class are public by default.
 Private variables are those variables that are defined in the class but can
be accessible by the methods of that class only.
 The private variables are used with double underscore( __ ) prefix.
 Protected variables :The members of a class that are declared protected
are only accessible to a class derived from it.
 Data members of a class are declared protected by adding a single
underscore (_) symbol before the data member of that class.

class ABC:
def __init__(self, var1, var2):
self.var1 = var1
self.__var2 = var2
def display(self):
print("From class method, variable 1 is: ", self.var1)
print("From class method, variable 2 is: ", self.__var2)
obj = ABC(10,20)
obj.display()
print("From class method, variable 1 is: ", obj.var1)
print("From class method, variable 2 is: ", obj.__var2)
Output:
From class method, variable 1 is: 10
Traceback (most recent call last)
---> 13 print("From class method, variable 2 is: ", obj.__var2)
AttributeError: 'ABC' object has no attribute '__var2'

To remove above error, to access private variable use
following syntax:
objectname._classname__privatevariable
Ex:
print("From class method, variable 2 is: ",obj._ABC__var2)

To access private method, use following syntax:
objectname._classname__privatemethodname
Ex:
class ABC:
def __init__(self, var):
self.__var = var
def __display(self):
print("From class method,variable is:",
self.__var)
obj = ABC(10)
obj._ABC__display()
Output:
From class method, variable is: 10

Write a program in python to Create class EMPLOYEE for storing details (Name,
Designation, gender, Date of Joining and Salary). Define function members to display all
EMPLOYEE details.
class Employee:
name = []
designation = []
gender = []
doj = []
salary = []
def __init__(self):
for i in range(3):
self.name.append(input("Enter the name:"))
self.designation.append(input("Enter the Designation:"))
self.gender.append(input("Enter the gender:"))
self.doj.append(input("Enter the doj:"))
self.salary.append(int(input("Enter the salary:")))

def display(self):
print("-------------Details of Employee-----------------")
print(" NamettDesignationtGenderttDate of
JoiningttSalary ")
print("-------------------------------------------------")
for i in range(3):
print(self.name[i],"tt",self.designation[i],"t",
self.gender[i],"tt",self.doj[i],"tt",self.salary[i] )
e = Employee()
e.display()
Output:
Enter the name:Sakshi
Enter the Designation:Manager
Enter the gender:Male
Enter the doj:10-06-2001
Enter the salary:50000

Enter the name:Rohit
Enter the Designation:Developer
Enter the gender:Male
Enter the name:Riya
Enter the Designation:Tester
Enter the gender:Female
----------------------Details of Employee--------------------------
Name Designation Gender Date of Joining Salary
-------------------------------------------------------------------
Sakshi Manager Male 10-06-2001 50000
Rohit Developer Male 10-05-2009 35000
Riya Tester Female 10-02-2012 20000

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