Common Python Interview Questions and Answers

1. How does Python manage memory? Python uses a private heap managed by the interpreter; objects are allocated in this heap and reclaimed by a built‑in garbage collector.

2. Explain Help() and Dir() functions. Help() displays documentation for modules, classes, functions, etc.; Dir() lists the attributes of an object (or the current namespace when called without arguments).

3. Does Python clear all allocated memory on exit? Objects with circular references and those referenced from the global namespace may not be freed; C‑level allocations remain.

4. What is monkey patching? Dynamically modifying a class or module at runtime.

5. What is a Python dictionary? A built‑in mapping type that stores key‑value pairs, allowing fast lookup via keys.

6. Explain logical operators. Python provides and , or , and not .

7. Why avoid leading underscores in identifiers? A leading underscore is a convention for “private” variables; identifiers should start with a letter or underscore, but using underscores for privacy is optional.

8. What is Flask? A lightweight Python web framework built on WSGI, using Werkzeug and Jinja2.

9. Explain join() and split(). join() concatenates an iterable of strings using a separator; split() divides a string into a list based on a delimiter.

10. How long can Python identifiers be? Identifiers can be of any length, but must start with a letter or underscore and may contain letters, digits, and underscores; they are case‑sensitive and cannot be keywords.

11. Is indentation required in Python? Yes; indentation defines code blocks such as loops, functions, and classes, typically using four spaces.

12. What does *args mean? It allows a function to accept an arbitrary number of positional arguments, which are received as a tuple.

13. Difference between shallow and deep copy. Shallow copy copies object references; changes affect the original. Deep copy creates independent copies of nested objects.

14. How to implement multithreading in Python? Python provides a threading module; due to the Global Interpreter Lock (GIL), threads run concurrently but not in parallel on a single CPU core.

15. What is a closure? A nested function that captures variables from its enclosing scope, retaining access to those values.

16. Advantages of Python. Easy to learn, fully object‑oriented, rich high‑level data structures, extensive standard library, cross‑platform and open source.

17. What is tuple unpacking? Assigning each element of a tuple to separate variables, e.g., x, y, z = (3, 4, 5) .

18. What is a PEP? Python Enhancement Proposal, a design document describing new features or standards for Python.

19. Difference between list and tuple. Lists are mutable; tuples are immutable.

20. What is a Python module and common built‑in modules? A .py file containing code (functions, classes, variables). Common modules include random , datetime , json , sys , math , etc.