Python Interview Questions and Answers

Basic Python Questions:

1. What is Python?

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

2. What are the key features of Python?

   • Some key features include:
     • Easy-to-read syntax
     • Dynamic typing
     • Automatic memory management (garbage collection)
     • High-level data types like lists, dictionaries, etc.
     • Extensive standard library
     • Platform independence

3. What is PEP 8?

   • PEP 8 is a style guide for Python code, containing guidelines for writing clean and readable code.

4. What are the different data types in Python?

   • Python supports various data types including int, float, complex, str, list, tuple, set, dict, bool, etc.

5. What is a Python dictionary?

   • A dictionary in Python is an unordered collection of items where each item is stored as a key-value pair.

6. What is a Python list comprehension?

   • List comprehension is a concise way to create lists in Python, providing a more readable and efficient way to generate lists.

7. What is the difference between range() and xrange() in Python 2?

   • range() returns a list, whereas xrange() returns an xrange object which behaves like an iterator.

Intermediate Python Questions:

8. What is the difference between __str__() and __repr__() in Python?

   • __str__() is called when str() is used, while __repr__() is called when repr() is used. __repr__() should return a string that can be used to recreate the object.

9. Explain Python decorators.

   • Decorators are functions that modify the behavior of other functions or methods. They allow you to wrap another function to extend or modify its behavior.

10. What is a lambda function in Python?

    • A lambda function is a small anonymous function defined using the lambda keyword. They can have any number of arguments but only one expression.

11. What is the purpose of __init__ in Python classes?

    • __init__ is a special method in Python classes used for initializing the object's state. It gets called automatically whenever a new object is created.

12. Explain the use of __name__ variable in Python.

    • __name__ is a special variable in Python that gets set to "__main__" if the script is being run directly, but to the module name if it is imported.

13. What is a module in Python?

    • A module is a file containing Python code. It can define functions, classes, and variables, and can also include runnable code.

Advanced Python Questions:

14. What are decorators with arguments?

    • Decorators with arguments are a way to customize the behavior of decorators. They are implemented by creating a function that returns a decorator.

15. Explain the GIL (Global Interpreter Lock).

    • The GIL is a mutex that protects access to Python objects, preventing multiple native threads from executing Python bytecodes simultaneously. This can limit the performance of multi-threaded Python programs.

16. What is monkey patching in Python?

    • Monkey patching is the dynamic modification of a class or module at runtime. It allows you to change or extend the behavior of code without altering the original source code.

17. Explain how memory management works in Python.

    • Python uses reference counting and a garbage collector for memory management. Objects are automatically deallocated when their reference count drops to zero, and the garbage collector periodically reclaims memory used by objects with circular references.

18. What are generators in Python?

    • Generators are a special kind of iterator that lazily generates values as they are needed. They are defined using the yield keyword and can be more memory-efficient than returning a list of values.

These questions cover a range of Python concepts and should give you a good foundation for a Python interview.