Python Interview Questions

Preparing for a Python-related interview can be daunting, but we’ve compiled a list of common and important questions categorized by difficulty level. These questions will help you showcase your Python knowledge and coding skills effectively.

Beginner-Level Python Interview Questions

1. What is Python? List some of its features.

Python is a high-level, interpreted programming language known for its simplicity and readability.
Features:

  • Easy to learn and use
  • Dynamic typing and garbage collection
  • Extensive standard library
  • Platform-independent

2. What are Python’s key data types?

  • Numeric Types: int, float, complex
  • Sequence Types: list, tuple, range
  • Text Type: str
  • Set Types: set, frozenset
  • Mapping Type: dict
  • Boolean Type: bool

3. What are Python’s built-in data structures?

  • Lists: Mutable sequences.
  • Tuples: Immutable sequences.
  • Dictionaries: Key-value pairs.
  • Sets: Unordered collections of unique items.

4. Explain the difference between is and ==.

  • is: Checks if two objects have the same memory address.
  • ==: Checks if two objects have the same value.

5. How does Python handle memory management?

Python uses automatic memory management with garbage collection to reclaim unused memory.

Intermediate-Level Python Interview Questions

6. What is a Python decorator?

A decorator is a function that modifies the behavior of another function or method.
Example:

def decorator_function(func):
    def wrapper():
        print("Before function call")
        func()
        print("After function call")
    return wrapper

@decorator_function
def my_function():
    print("Hello, World!")

my_function()

7. What is the difference between a shallow copy and a deep copy?

  • Shallow Copy: Copies the reference of objects. Changes in the copied object affect the original. (copy.copy)
  • Deep Copy: Recursively copies all objects. Changes in the copied object do not affect the original. (copy.deepcopy)

8. What are Python’s methods for file handling?

  • open(): Opens a file.
  • read(), readline(), readlines(): Read contents of a file.
  • write() and writelines(): Write to a file.
  • close(): Closes the file.

9. Explain Python’s Global Interpreter Lock (GIL).

GIL is a mutex in Python that allows only one thread to execute Python bytecode at a time, making multi-threading less effective in CPU-bound tasks.

10. What is the purpose of the with statement in Python?

The with statement simplifies exception handling by automatically closing resources.
Example:

with open("file.txt", "r") as file:
    content = file.read()

Advanced-Level Python Interview Questions

11. How does Python’s garbage collector work?

Python uses reference counting and a cyclic garbage collector to manage memory. It identifies and collects objects with zero references or circular references.

12. What is the difference between Python’s @staticmethod, @classmethod, and regular methods?

  • Static Method: Does not take the instance or class as an argument.
  • Class Method: Takes the class (cls) as an argument.
  • Instance Method: Takes the instance (self) as an argument.

13. How do you handle exceptions in Python?

Use try, except, else, and finally blocks.
Example:

try:
    x = 10 / 0
except ZeroDivisionError:
    print("Cannot divide by zero!")
finally:
    print("Execution complete.")

14. What are metaclasses in Python?

Metaclasses control the creation of classes. Classes are instances of metaclasses.
Example:

class Meta(type):
    def __new__(cls, name, bases, dct):
        print(f"Creating class {name}")
        return super().__new__(cls, name, bases, dct)

class MyClass(metaclass=Meta):
    pass

15. What is the difference between deepcopy() and pickle?

  • deepcopy(): Used for copying objects.
  • pickle: Used for serializing and deserializing objects.

Python Coding Challenges for Interviews

  1. Reverse a string without using slicing.
  2. Find the second largest number in a list.
  3. Implement a stack using lists.
  4. Write a function to check for balanced parentheses in a string.
  5. Count the frequency of characters in a string.

Tips for Cracking Python Interviews

  1. Understand the Basics: Be clear on Python syntax, data types, and OOP concepts.
  2. Practice Coding: Solve problems on platforms like LeetCode, HackerRank, and CodeSignal.
  3. Be Prepared for Real-World Applications: Study libraries and frameworks relevant to the job.
  4. Communicate: Explain your thought process while solving problems.
  5. Learn Advanced Topics: Dive into topics like multithreading, metaprogramming, and data analysis if applicable.

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