Top 50 Python Interview Questions for Freshers

Introduction

Python is a versatile and widely-used programming language that emphasizes simplicity and readability, making it a popular choice for developers across many domains. Whether you're a beginner or an experienced coder, understanding Python’s basic, intermediate, and advanced concepts is crucial for mastering the language and excelling in interviews. The following is a comprehensive list of commonly asked Python interview questions, with answers covering fundamental concepts, data structures, object-oriented programming, file handling, and more. Review these to prepare effectively for your next Python interview.

Basic Questions

1. What is Python?
   Python is a high-level, interpreted programming language with great readability, and its wide applicability can be seen in web development, data analysis, AI, scientific computing, and much more.

2. How does Python manage memory?
   Python uses private heap space for memory management; it is taken care of by the memory manager. It also contains built-in garbage collection.

3. Difference between lists and tuples:
   In Python, lists are mutable objects whose elements can be changed after they have been assigned. Tuples, on the other hand, are immutable, meaning their elements cannot be changed after assignment.

4. How do you manage packages in Python?
   Python package management is performed using the pip tool, which installs packages for Python programs.

Intermediate Questions

1. What are Python decorators?
   A decorator is a special kind of function that can modify another function or method.

2. What is the difference between range() and xrange()?
   In Python 2, the former creates a list while the latter returns an iterator. In Python 3, xrange() no longer exists, but range() behaves like xrange().

3. Explain the concept of scope in Python.
   Scope refers to the visibility of variables in different parts of the program, which are distinguished into local, global, enclosing, and built-in scopes.

Advanced Questions

1. What is a Python generator?
   A generator is a function that returns an iterable set of items one at a time, using the yield statement.

2. How does Python handle errors?
   Python makes use of try-except blocks to handle errors gracefully.

3. What is the Global Interpreter Lock (GIL)?
   The GIL is a mutex that protects access to Python objects, preventing multiple native threads from executing Python bytecodes at once.

Data Structures and Algorithms

1. What is a Python dictionary?
   A dictionary is an unordered collection of data in key-value pairs, optimized for fast lookups.

2. Explain list comprehensions.
   List comprehensions are a way to create lists using a single line of code for iterative operations.

3. How would you reverse a string in Python?
   The easiest way to reverse a string is with slicing: string[::-1].

Object-Oriented Programming

1. What is inheritance in Python?
   Inheritance allows a class to inherit the attributes and methods of another class, encouraging code reuse.

2. Define polymorphism.
   Polymorphism allows methods to perform different tasks based on the object that it's operating on. It is commonly seen in method overriding.

3. What's the difference between __init__ and __new__?
   __init__ initializes a new object, while __new__ creates a new instance of a class.

File Handling

1. How do you read and write files in Python?
   Use the open() function with appropriate modes ('r' for reading, 'w' for writing).

2. How do you handle exceptions during file operations?
   Use try-except blocks around file operations to catch and handle exceptions.

Libraries and Frameworks

1. What are some popular Python libraries for data science?
   NumPy, pandas, Matplotlib, and SciPy are widely used for data science tasks.

2. What is Flask, and what is it used for?
   Flask is a micro-framework for building small to medium-sized web applications quickly.

Coding Challenges

1. Write a Python function to check if a number is prime.

def is_prime(n): if n <= 1: return False for i in range(2, int(n**0.5) + 1): if n % i == 0: return False return True 

1. Write a Python program to merge two sorted lists.

def merge_lists(list1, list2): return sorted(list1 + list2) 

More Questions

1. Explain lambda functions.
   Lambda functions are anonymous, small functions defined with the lambda keyword. They can take any number of arguments but return only one expression.

2. How do you handle memory leaks in Python?
   Memory leaks in Python are often caused by unclosed file handles, lingering circular references, or improperly managed objects. To prevent leaks, ensure proper resource management (e.g., using with for files) and avoid circular references or break them explicitly.

3. Describe self in Python.
   self is a reference to the instance of the class, used to access instance variables and methods. It allows you to refer to the current object within class methods.

4. What is PEP8?
   PEP8 is the Python Enhancement Proposal that provides guidelines for writing clean, readable, and consistent Python code.

5. What are Python modules and packages?
   A module is a single file of Python code that can be imported, while a package is a collection of modules in a directory, with an __init__.py file.

6. How does Python handle multithreading?
   Python supports multithreading, but the GIL limits its ability to execute multiple threads concurrently in CPython. However, threads are still useful for I/O-bound tasks.

7. Explain __repr__ and __str__.

• __repr__ is meant to give a detailed and unambiguous string representation of an object, typically for debugging.
• __str__ is meant to give a human-readable string representation of an object for display.

1. What is pickling?
   Pickling is the process of serializing Python objects into a byte stream that can be written to a file or transmitted over a network. The reverse process is called unpickling.

2. Describe the difference between Python 2 and Python 3.
   Python 3 introduced several improvements over Python 2, including better Unicode support, print function syntax, and division behavior (true division in Python 3).

3. What is a Python closure?
   A closure is a function that captures the state of its enclosing lexical scope even after the outer function has finished executing.

4. How do you create virtual environments in Python?
   You can create a virtual environment with the venv module:

python -m venv myenv 

1. What are Python iterators?
   Iterators are objects that implement the __iter__() and __next__() methods, allowing iteration over elements one by one.

2. How do you sort a dictionary by value?
   You can sort a dictionary by value using the sorted() function with a custom sorting key:

sorted_dict = sorted(my_dict.items(), key=lambda x: x[1]) 

1. Explain method overriding.
   Method overriding occurs when a subclass provides a specific implementation of a method that is already defined in its superclass.

2. What is monkey patching?
   Monkey patching is the practice of dynamically modifying or extending a module or class at runtime.

3. Describe the differences between deepcopy and copy.
   copy() creates a shallow copy of an object, meaning it copies the object but references the inner objects. deepcopy() creates a new object and recursively copies all objects inside, resulting in a completely independent copy.

4. What is argparse in Python?
   argparse is a library used for parsing command-line arguments passed to a Python script, allowing you to write user-friendly command-line interfaces.

5. How do you handle circular imports?
   Circular imports occur when two or more modules depend on each other. To avoid this, you can import inside a function or method, rather than at the top level, to delay the import until necessary.

6. What is the purpose of the pass statement?
   The pass statement is a placeholder in Python. It is used when you need to define an empty block of code or want to leave a function or class definition empty.

7. How does zip() work?
   zip() takes two or more iterables and aggregates them into a tuple of corresponding elements.

8. Describe the with statement in Python.
   The with statement is used for resource management (e.g., working with files). It ensures that resources are properly cleaned up after use.

9. **Describe how *args and kwargs are used.

• *args allows you to pass a variable number of non-keyword arguments to a function.
• **kwargs allows you to pass a variable number of keyword arguments to a function.

1. What is the usage of map() in Python?
   map() applies a given function to each item in an iterable and returns a map object (an iterator) of the results.

2. Describe what yield from does.
   yield from simplifies the process of yielding values from a generator or iterable, making code cleaner and more efficient.

3. What is the use of __name__?
   __name__ is a special variable that determines if a script is being run directly or imported as a module. If it's being run directly, __name__ is set to '__main__'.

4. How does Python implement switch-case statements?
   Python does not have a built-in switch or case statement. However, similar functionality can be achieved using dictionaries, if-elif chains, or match statements (introduced in Python 3.10).

5. What is a namespace in Python?
   A namespace is a container that holds a collection of identifiers (variable names) and their corresponding objects. Examples include local, global, and built-in namespaces.

6. What are metaclasses in Python?
   Metaclasses are classes of classes in Python. They define the behavior and structure of classes themselves, rather than instances of classes.

Good luck with your Python interview preparation! ✨