Top Python Interview Questions and Answers

Here are top Python interview questions,

1. What is Python? Why is it popular?

Python is a high-level, interpreted programming language known for its simplicity, readability, and versatility. It is popular due to its large standard library, extensive third-party libraries, and wide range of applications.

 

2. Explain the difference between Python 2 and Python 3.

Python 3 is the latest version and has significant differences from Python 2, including print function as a built-in function, improved Unicode support, syntax changes, and better handling of exceptions.

 

3. What are the key data types in Python?

The main data types in Python are integers, floats, strings, lists, tuples, dictionaries, and sets.

 

4. What is the difference between a list and a tuple?

Lists are mutable, meaning they can be modified, whereas tuples are immutable and cannot be changed once created.

 

5. What are the differences between shallow copy and deep copy?

Shallow copy creates a new object but references the same memory locations, while deep copy creates a new object and recursively copies the content to different memory locations.

 

6. What is a decorator in Python?

A decorator is a design pattern in Python that allows modifying the behavior of a function or class without changing its source code. It uses the `@decorator_name` syntax and is useful for logging, authorization, and other cross-cutting concerns.

 

7. What is a generator in Python?

A generator is a function that can be paused and resumed, allowing the generation of a sequence of values over time. It uses the `yield` keyword to produce values one at a time, optimizing memory usage.

 

8. Explain the concept of Python iterators.

Iterators are objects that allow traversal over a sequence of elements. They implement the `__iter__()` and `__next__()` methods. The `__iter__()` method returns the iterator object itself, and the `__next__()` method returns the next element in the sequence.

 

9. What is the purpose of the `__init__` method in Python classes?

The `__init__` method is a special method in Python classes that is automatically called when an object is created from a class. It initializes the object's attributes and performs any necessary setup.

 

10. How can you handle exceptions in Python?

Exceptions can be handled using a `try-except` block. The code that may raise an exception is placed inside the `try` block, and the handling code is written in the `except` block.

 

11. What are the differences between `range` and `xrange`?

In Python 2, `range` returns a list, while `xrange` returns an xrange object that generates values on the fly. In Python 3, `range` behaves like `xrange` of Python 2.

 

12. Explain the Global Interpreter Lock (GIL) in Python.

The GIL is a mechanism in CPython (the standard Python implementation) that allows only one thread to execute Python bytecode at a time. This can impact the performance of multithreaded CPU-bound programs but doesn't affect I/O-bound or multiprocessing tasks.

 

13. How do you handle file I/O in Python?

File I/O can be handled using the `open()` function to open a file, specifying the mode (read, write, append, etc.). After usage, the file should be closed using the `close()` method or using the `with` statement.

 

14. What are Python modules and packages?

Modules are files containing Python code that define functions, classes, and variables. Packages are directories containing multiple modules and an additional `__init__.py` file. They help organize and reuse code.

 

15. Explain the concept of recursion in Python.

Recursion is a technique where a function calls itself to solve a smaller instance of the same problem. It consists of a base case (stopping condition) and a recursive case (the function calling itself).

 

16. How do you handle multiple exceptions in Python?

Multiple exceptions can be handled using multiple `except` blocks or by using a tuple of exception types in a single `except` block.

 

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

Shallow copy creates a new object but references the same memory locations, while deep copy creates a new object and recursively copies the content to different memory locations.

 

18. How do you handle and raise custom exceptions in Python?

Custom exceptions can be created by defining a new class that inherits from the `Exception` class. To raise an exception, the `raise` keyword followed by an instance of the custom exception class is used.

 

19. What are Python decorators used for?

Decorators are a way to modify the behavior of functions or classes without changing their source code. They are often used for logging, authentication, timing, and adding functionality to existing code.

 

20. How do you sort a list of objects in Python?

To sort a list of objects, you can use the `sort()` method and provide a custom sorting key using a lambda function or by implementing the `__lt__()` method in the objects being sorted.

Above are top Python interview questions. Remember to prepare and expand on these answers. 

Good luck with your interview!  👍