Are you preparing for a Python OOPs interview and feeling unsure about what to expect? With Python’s object-oriented programming (OOP) principles being a core part of many tech roles – it’s important to be well-prepared. Did you know? OOP concepts feature in many Python-related job interviews. To help you deal with this – we’ve compiled a list of the top 25+ Python OOPs interview questions. These questions cover fundamental topics and advanced scenarios to give you a solid foundation and boost your confidence.Â
So, let’s get started!
Python OOPs Interview Questions for Freshers
Here are some common OOPs interview questions in python for freshers and their answers.
- Can you explain OOP in Python?
OOP (Object-Oriented Programming) is a programming paradigm that uses objects and classes to structure code. It allows for code reusability, modularity, and abstraction. Python supports OOP by enabling the creation and manipulation of objects.
- What is a class in Python?
A class in Python is a blueprint for creating objects. It defines properties (attributes) and behaviours (methods) that the objects created from the class will have. Classes encapsulate data and functions that operate on the data.
- How would you define an object in Python?
This is one of the key OOPs concepts in Python interview questions.
An object is an instance of a class. When a class is defined, no memory is allocated until an object is created. An object holds the attributes defined by the class.
- What is the difference between a class variable and an instance variable?
Class variables are shared among all instances of a class. They are defined within the class but outside any method.
Instance variables are unique to each object (instance of the class) and are defined within the constructor (__init__ method).
- What is inheritance in Python?
Inheritance allows one class to derive or inherit properties and methods from another class. This promotes code reuse. The class that inherits is called the “child” or “subclass,” and the class it inherits from is called the “parent” or “superclass.”
- Can you explain polymorphism?
Polymorphism refers to the ability of different objects to respond to the same method or function in different ways. Python supports polymorphism through method overriding and method overloading.
- How do you achieve method overriding in Python?
Method overriding in Python occurs when a subclass provides a specific implementation for a method that is already defined in its superclass. This allows the subclass to modify or extend the behaviour of the inherited method.
Python OOPs Interview Questions for ExperiencedÂ
Here are some important OOP in Python interview questions for experienced and their answers.
- What is the difference between classmethod, staticmethod, and instance methods in Python?
- Instance methods: Operate on an instance of the class using the self parameter. They can access and modify the object’s attributes.
- Class methods: Use the @classmethod decorator and take cls as the first parameter. They operate on the class itself and can modify class-level attributes.
- Static methods: Use the @staticmethod decorator and do not take self or cls. They behave like regular functions, but they belong to the class’s namespace.
- How does Python support multiple inheritance, and what are the potential issues?
Python allows a class to inherit from multiple base classes. However, this can lead to issues such as the Diamond Problem – where a class inherits from two classes that have a common ancestor. Python resolves this using the Method Resolution Order (MRO) – which follows the C3 linearization algorithm.
- Can you explain the concept of a metaclass in Python?
A metaclass is a class of a class. It defines how classes are created and can be used to control the behaviour of class creation. By default, Python uses type as the metaclass, but custom metaclasses can be created by subclassing type.
- How does Python handle private and protected members in classes?
Python does not have strict private or protected members like other languages. However, conventionally:
Protected members are indicated by a single underscore (_). These can still be accessed outside the class but are intended for internal use.
Private members are indicated by double underscores (__), which triggers name mangling, making it harder (but not impossible) to access from outside the class.
- How does Python’s garbage collection work in the context of object-oriented programming?
Python uses a reference counting system along with a cyclic garbage collector to manage memory. When an object’s reference count drops to zero, the memory is deallocated. The garbage collector handles circular references by periodically scanning for unreachable objects in cycles.
- What are mixins, and when would you use them in Python?
A mixin is a class that provides additional functionality to other classes without being their parent class. Mixins allow for code reuse by sharing behaviour across multiple classes without using inheritance.
Advanced Python Object Oriented Programming Interview Questions
These are some advanced Python Object Oriented interview questions and their answers.
- What is the purpose of the __slots__ in Python classes, and how does it improve performance?
__slots__ is a mechanism to prevent the dynamic creation of instance attributes and reduce memory usage. By defining __slots__, you can restrict the class to only the attributes listed in the slots – which leads to a smaller memory footprint since it avoids the overhead of maintaining an attribute dictionary (__dict__).
- How do you implement a property in Python, and how does it differ from a regular attribute?
Python’s @property decorator allows you to define methods that act as attributes – providing a controlled way of accessing and setting instance data. This is useful for adding logic around getting and setting values without changing the external interface.
- Can you explain duck typing in Python?
Duck typing is a feature of dynamic languages like Python where the type or class of an object is less important than the methods or properties it defines. As long as an object implements the required behaviour (method) – it can be used, irrespective of its type. The name comes from the phrase: “If it looks like a duck and quacks like a duck, it’s a duck.”
- What is the role of super() in Python OOP?
The super() function is used to call a method from a parent class in Python. It allows subclasses to extend or modify the behaviour of inherited methods without explicitly referencing the parent class – guaranteeing better maintainability and compatibility, especially in the case of multiple inheritance.
- What is the difference between is and == in Python?
The == operator checks for value equality – meaning it compares whether the values of two objects are the same.
The is operator checks for reference equality – meaning it checks whether two variables point to the same object in memory.
Python OOPs Programming Interview Questions
Here are some important OOPs practice questions in Python and their answers.
- Write a Python class to represent a Bank Account with methods to deposit, withdraw, and check balance.
class BankAccount:
def __init__(self, owner, balance=0):
self.owner = owner
self.balance = balance
def deposit(self, amount):
self.balance += amount
return f”Deposited {amount}. New balance is {self.balance}”
def withdraw(self, amount):
if amount > self.balance:
return “Insufficient balance”
self.balance -= amount
return f”Withdrawn {amount}. Remaining balance is {self.balance}”
def check_balance(self):
return f”Account balance: {self.balance}”
# Example usage:
account = BankAccount(“Alice”, 100)
print(account.deposit(50)) # Deposited 50. New balance is 150
print(account.withdraw(30)) # Withdrawn 30. Remaining balance is 120
print(account.check_balance()) # Account balance: 120
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- Create a Python class hierarchy for a Vehicle, with subclasses Car and Motorcycle, and implement a speed method for both subclasses.
class Vehicle:
def __init__(self, brand, max_speed):
self.brand = brand
self.max_speed = max_speed
def speed(self):
raise NotImplementedError(“Subclasses must implement this method”)
class Car(Vehicle):
def speed(self):
return f”The car can go up to {self.max_speed} km/h.”
class Motorcycle(Vehicle):
def speed(self):
return f”The motorcycle can go up to {self.max_speed} km/h.”
# Example usage:
car = Car(“Toyota”, 180)
bike = Motorcycle(“Yamaha”, 120)
print(car.speed()) # The car can go up to 180 km/h.
print(bike.speed()) # The motorcycle can go up to 120 km/h.
- Write a Python class to implement a stack (LIFO) using OOP principles.
class Stack:
def __init__(self):
self.items = []
def push(self, item):
self.items.append(item)
def pop(self):
if not self.is_empty():
return self.items.pop()
return “Stack is empty”
def peek(self):
if not self.is_empty():
return self.items[-1]
return “Stack is empty”
def is_empty(self):
return len(self.items) == 0
def size(self):
return len(self.items)
# Example usage:
stack = Stack()
stack.push(10)
stack.push(20)
print(stack.peek()) # 20
print(stack.pop()) # 20
print(stack.pop()) # 10
print(stack.pop()) # Stack is empty
- Design a Python class to represent a Rectangle and a Square, and ensure Square inherits from Rectangle. Include methods to calculate the area and perimeter.
class Rectangle:
def __init__(self, width, height):
self.width = width
self.height = height
def area(self):
return self.width * self.height
def perimeter(self):
return 2 * (self.width + self.height)
class Square(Rectangle):
def __init__(self, side):
super().__init__(side, side)
# Example usage:
rect = Rectangle(4, 5)
square = Square(4)
print(rect.area()) # 20
print(rect.perimeter()) # 18
print(square.area()) # 16
print(square.perimeter()) # 16
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Python OOPs MCQs
Here are some common Python OOPs MCQs and their answers.
- Which of the following is used to define a method that can be called on a class itself rather than an instance?
- A) @staticmethod
- B) @classmethod
- C) @property
- D) @abstractmethod
Answer: B) @classmethod
- What is the result of accessing an attribute that starts with a double underscore (__) from outside the class?
- A) The attribute is accessible directly.
- B) The attribute raises an AttributeError.
- C) The attribute is name-mangled and can be accessed with a specific name.
- D) The attribute is inherited by all subclasses.
Answer: C) The attribute is name-mangled and can be accessed with a specific name.
- Which method is called automatically when a new instance of a class is created?
- A) __str__
- B) __init__
- C) __new__
- D) __call__
Answer: B) __init__
- Which of the following is NOT a type of method in Python classes?
- A) Instance method
- B) Class method
- C) Static method
- D) Factory method
Answer: D) Factory method
- What will happen if a subclass does not implement an abstract method defined in its base class?
- A) The subclass will be instantiated with a default implementation.
- B) The code will raise a TypeError at runtime when an instance is created.
- C) The subclass will be instantiated without any error.
- D) The abstract method will be ignored.
Answer: B) The code will raise a TypeError at runtime when an instance is created.
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Wrapping Up
Here are the top 25+ Python OOPs interview questions that cover essential concepts for understanding object-oriented programming. These questions will help you prepare for interviews by testing your knowledge of classes, inheritance, methods, and more. For python job opportunities – check out Hirist—it’s an online job portal where you can find the best IT jobs in India and abroad.
