python-notes

Top 10 Python interview questions with answers!

Here are the top 10 Python interview questions with concise answers and code examples where applicable:

1. What is Python? What are its key features?

Python is a high-level, interpreted, general-purpose programming language known for its simple, readable syntax. Key features include dynamic typing, automatic memory management, extensive libraries, and support for multiple programming paradigms (object-oriented, procedural, and functional)[^1_1].

2. How does Python handle memory management?

Python uses automatic memory management with a built-in garbage collector. Memory is allocated and deallocated automatically as objects are created and destroyed. Reference counting and cyclic garbage collection are employed to manage and free memory efficiently[^1_1].

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

• List: Mutable, can be changed after creation. Syntax: [^1_2][^1_3][^1_4]
• Tuple: Immutable, cannot be changed after creation. Syntax: (1, 2, 3)

Example:

my_list = [1, 2, 3]
my_tuple = (1, 2, 3)
my_list[^1_0] = 4  # Valid
# my_tuple[^1_0] = 4  # Raises TypeError

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

__init__ is the constructor method that initializes a new class instance’s attributes when the object is created.

Example:

class Dog:
    def __init__(self, name):
        self.name = name
d = Dog("Buddy")

5. What are *args and **kwargs?

• *args allows a function to accept any number of positional arguments.
• **kwargs allows any number of keyword arguments.

Example:

def demo(*args, **kwargs):
    print(args)
    print(kwargs)
demo(1, 2, three=3, four=4)
# Output: (1, 2), {'three': 3, 'four': 4}

6. What are list comprehensions? Give an example.

List comprehensions provide a concise way to create lists using a single line of code.

Example:

squares = [x*x for x in range(6)]
# Output: [0, 1, 4, 9, 16, 25]

7. What is a Python decorator?

A decorator is a function that modifies the behavior of another function without changing its code, usually prefixed with @.

Example:

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

@decorator_func
def say_hello():
    print("Hello!")
say_hello()

8. What is a generator? How is it different from a regular function?

A generator is a function that returns an iterator which yields one value at a time, using the yield statement. Generators don’t store all values in memory, making them memory efficient.

Example:

def count_up_to(n):
    count = 1
    while count <= n:
        yield count
        count += 1

9. How do you handle exceptions in Python?

You use try, except, else, and finally blocks to handle exceptions.

Example:

try:
    x = 1 / 0
except ZeroDivisionError:
    print("You can't divide by zero!")
finally:
    print("Execution complete")

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

• Shallow copy: Copies reference to objects only. Changes to nested objects affect both copies.
• Deep copy: Copies everything recursively. Changes in nested objects do not affect the original.

Example:

import copy
lst1 = [[1, 2], [3, 4]]
lst2 = copy.copy(lst1)    # Shallow copy
lst3 = copy.deepcopy(lst1) # Deep copy

These questions and answers cover concepts commonly tested in Python interviews.