Interview Prep Guide

Python Interview Questions and Answers for Freshers to Experienced Developers

Prepare for Python interviews with practical questions about language basics, decorators, generators, memory behavior, and coding rounds.

Basic Python Interview Questions

  1. What is the difference between a list and a tuple in Python?

    A list is mutable, while a tuple is immutable after creation.

  2. What is a list comprehension?

    A list comprehension is a concise way to create a new list by iterating over an iterable and optionally filtering or transforming values.

  3. What is the difference between == and equals() in Java?

    == compares object references for identity, while equals() compares logical equality when the class implements it appropriately.

  4. What are the accessibility modifiers in Java?

    Java has four main access levels: private (class only), default (package only), protected (package + subclasses), and public (everywhere).

  5. What is the difference between is and == in Python?

    == compares values, while is compares object identity, meaning whether two references point to the same object.

  6. What are lambda functions in Python?

    Lambda functions are small, anonymous functions defined with the lambda keyword, used for short pieces of logic where a full def statement is unnecessary.

  7. What are docstrings and why are they used?

    Docstrings are string literals that appear right after a function, class, or module definition, used to document what the code does.

Medium Python Interview Questions

  1. What is a decorator in Python?

    A decorator is a function that wraps another function or method to extend its behavior without changing the original implementation directly.

  2. What is a generator and when would you use one?

    A generator yields values lazily one at a time instead of building the entire collection in memory at once.

  3. What are *args and **kwargs in Python?

    *args collects extra positional arguments and **kwargs collects extra keyword arguments, which makes functions more flexible when needed.

  4. What is the difference between classmethod and staticmethod?

    A classmethod receives the class (cls) as its first argument and can access class state, while a staticmethod receives no implicit first argument and behaves like a regular function restricted to the class namespace.

  5. How does exception handling work in Python?

    Python uses try, except, else, and finally blocks to catch and handle errors gracefully without crashing the program.

Advanced Python Interview Questions

  1. What is the GIL and why does it matter?

    The Global Interpreter Lock allows only one thread at a time to execute Python bytecode in the standard CPython interpreter, which matters for CPU-bound threading behavior.

  2. What is the difference between shallow copy and deep copy?

    A shallow copy duplicates the outer container but still references nested objects, while a deep copy recursively copies nested structures too.

  3. How does Python memory management work at a high level?

    Python manages memory automatically through reference counting plus garbage collection for cyclic references, so developers mainly think about object lifetime and accidental retention.

  4. What is Method Resolution Order (MRO) in Python?

    MRO is the order in which Python looks for a method or attribute in a hierarchy of classes, especially important in multiple inheritance.

  5. What are __slots__ and when should you use them?

    __slots__ is a class attribute that tells Python not to use a dynamic dictionary (__dict__) for instances, which saves significant memory for millions of small objects.

Scenario-Based Python Interview Questions

  1. How would you choose between synchronous code, asyncio, threading, and multiprocessing in a Python service?

    Choose based on workload type: asyncio or threads for I/O-heavy work, multiprocessing for CPU-heavy work, and simple synchronous code when concurrency is unnecessary.

Python Coding Round

  1. Build a small rate-limiter or frequency counter utility

    Interviewers usually care less about clever tricks and more about clarity. A strong answer chooses the right data structure first, names variables clearly, and explains edge cases before optimizing further.

  2. Write a function to check if two strings are anagrams

    A simple sorting approach is easy to explain, but a character frequency counter (using a dictionary or Counter ) is more efficient (O(n) time). High-quality answers also clarify whether the comparison should ignore spaces or case.

  3. Implement a resilient data-processing function with validation, retries, and clear error handling

    Strong answers use clear function boundaries, sensible exception handling, and readable control flow. Interviewers usually prefer maintainable Python over clever one-liners that are hard to debug later.