Python OOP Interview Questions (Top 50+)

Object-Oriented Programming (OOP) is a core concept in Python and is frequently asked in interviews. It helps in structuring programs using classes and objects.

This guide covers the most important Python OOP interview questions with examples and explanations.

1. OOP Basics

Q1. What is OOP?

OOP is a programming paradigm based on objects and classes.

Q2. What is a class?

A class is a blueprint for creating objects.

Q3. What is an object?

An object is an instance of a class.

Q4. Define encapsulation.

Encapsulation is binding data and methods together.

2. Class and Object Questions

              
Python

          Basic class example
        
class Person:
    def __init__(self, name):
        self.name = name

p = Person("John")
print(p.name)

Q5. What is __init__?

It is a constructor used to initialize objects.

3. Inheritance Questions

              
            
Python

          Inheritance example
        
class A:
    def show(self):
        print("A")

class B(A):
    pass

b = B()
b.show()

Q6. Types of inheritance?

Single, multiple, multilevel, hierarchical.

4. Polymorphism Questions

              
Python

          Polymorphism example
        
def add(a, b, c=0):
    return a + b + c

print(add(1,2))
print(add(1,2,3))

Q7. What is polymorphism?

Ability to take multiple forms.

5. Abstraction Questions

              
Python

          Abstraction example
        
from abc import ABC, abstractmethod

class Shape(ABC):
    @abstractmethod
    def area(self):
        pass

Q8. What is abstraction?

Hiding implementation details.

6. Encapsulation Questions

              
Python

          Encapsulation example
        
class Test:
    def __init__(self):
        self.__x = 10

    def get(self):
        return self.__x

Q9. What is private variable?

Variable prefixed with __ (double underscore).

7. Advanced OOP Questions

Q10. What is method overloading?

Not directly supported, achieved using default arguments.

Q11. What is method overriding?

Child class redefining parent method.

              
            
Python

          Method overriding
        
class A:
    def show(self):
        print("A")

class B(A):
    def show(self):
        print("B")

8. Coding Problems

Problem 1: Create class with methods

              
Python

          Simple class
        
class Calc:
    def add(self, a, b):
        return a + b

Problem 2: Bank Account class

              
Python

          Bank account
        
class Bank:
    def __init__(self, balance):
        self.balance = balance

    def deposit(self, amt):
        self.balance += amt

9. Common Mistakes

1. Confusing class and object.

2. Not using self keyword.

3. Misunderstanding inheritance.

4. Ignoring encapsulation.

10. Interview Tips

1. Understand OOP concepts clearly.

2. Practice coding examples.

3. Explain concepts with real-life examples.

4. Focus on implementation.

Conclusion

OOP is a fundamental concept in Python interviews. Mastering classes, inheritance, and polymorphism will help you crack interviews easily.

Practice regularly and build projects using OOP concepts.