Python has become one of the most popular programming languages, known for its simplicity, readability, and extensive libraries. Whether you're a seasoned developer or a novice, preparing for a Python interview can be daunting. This article aims to provide a comprehensive guide to common Python interview questions and how to tackle them effectively.

Basic Python Questions:-

Q1.  What are Python's Key Features?

Python is known for its:

• Simplicity and Readability: Its syntax is clear and easy to learn.
• Interpreted Nature: Python code is executed line by line, which helps in debugging.
• Dynamically Typed: Variables do not need explicit declaration to reserve memory space.
• Extensive Standard Library: Python provides modules and packages for various tasks.
• Community Support: A large and active community contributes to a vast repository of libraries and frameworks.

 Q2. Explain the Differences Between Python 2 and           Python 3.

Python 3 introduced several changes to improve the language:

• Print Function: print is a function in Python 3 (print('Hello')).
• Integer Division: Division of integers results in a float (5 / 2 gives 2.5).
• Unicode Support: Strings are Unicode by default in Python 3.
• Libraries: Many Python 3 libraries are incompatible with Python 2. 

Q3. What is PEP 8 and why is it important?

• PEP 8 is the Python Enhancement Proposal that provides guidelines and best practices on how to write Python code. It is important because it helps maintain consistency and readability in the codebase.

Intermediate Python Questions

Q4.What are Python Decorators?

Decorators are a way to modify the behavior of a function or class. They are often used for logging, enforcing access control, instrumentation, and caching. Here’s a simple example:

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def my_decorator(func):

    def wrapper():

        print("Something is happening before the function is called.")

        func()

        print("Something is happening after the function is called.")

    return wrapper

 

@my_decorator

def say_hello():

    print("Hello!")

 

say_hello()

Q5 Explain List Comprehensions and Provide an Example.

List comprehensions provide a concise way to create lists. They consist of brackets containing an expression followed by a for clause, then zero or more for or if clauses.

Example:

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squares = [x**2 for x in range(10)]

print(squares)  # Output: [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]

 

Q6. What are Generators in Python?

Generators are a simple way of creating iterators. They use the yield keyword instead of return to produce a series of values lazily, which means they generate values on the fly and don’t store them in memory.

Example:

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def countdown(n):

    while n > 0:

        yield n

        n -= 1

 

for i in countdown(5):

    print(i)  # Output: 5, 4, 3, 2, 1

Q7.Explain the Global Interpreter Lock (GIL).

The Global Interpreter Lock (GIL) is a mutex that protects access to Python objects, preventing multiple threads from executing Python bytecode at once. This means that even on multi-core systems, only one thread executes Python code at a time. While this simplifies memory management, it can be a bottleneck in CPU-bound and multithreaded programs.

Q8. Explain the difference between list and tuple in Python.

• Lists are mutable, meaning they can be modified after their creation. Tuples are immutable, meaning once they are created, they cannot be changed. This immutability makes tuples faster and more memory-efficient.

Q9. What are Python decorators and how are they used?

• Decorators are a way to modify or extend the behavior of functions or methods without changing their actual code. They are often used for logging, access control, and memoization. A decorator is applied with the @decorator_name syntax above the function definition.

Q 10. How does exception handling work in Python?

 

• Exception handling in Python is done using the try, except, else, and finally blocks. The try block contains code that might raise an exception, the except block handles the exception, the else block runs if no exception is raised, and the finally block runs no matter what, often used for cleanup code.

Q11. What is the Global Interpreter Lock (GIL)?

• The GIL is a mutex that protects access to Python objects, preventing multiple threads from executing Python bytecodes at once. This means that Python threads are not truly concurrent in a multi-core system. The GIL can be a performance bottleneck in CPU-bound and multithreaded code.

Q12. Explain the concept of generators in Python.

• Generators are a type of iterable, like lists or tuples. Unlike lists, generators do not store all their values in memory; they generate values on the fly. This makes them more memory-efficient for large datasets. They are defined using the yield keyword.

Q13. What are metaclasses in Python?

• Metaclasses are classes of classes, meaning they define the behavior of other classes. They allow you to control the creation and behavior of classes. Metaclasses are rarely used, but they can be powerful tools for creating APIs and frameworks.

Problem-Solving Questions

Q14. Write a Function to Check if a String is a Palindrome.

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def is_palindrome(s):

    s = s.replace(" ", "").lower()

    return s == s[::-1]

 

print(is_palindrome("A man a plan a canal Panama"))  # Output: True

 

Q15. Implement a Function to Merge Two Sorted Lists.

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def merge_sorted_lists(list1, list2):

    merged_list = []

    i = j = 0

 

    while i < len(list1) and j < len(list2):

        if list1[i] < list2[j]:

            merged_list.append(list1[i])

            i += 1

        else:

            merged_list.append(list2[j])

            j += 1

 

    merged_list.extend(list1[i:])

    merged_list.extend(list2[j:])

    return merged_list

 

list1 = [1, 3, 5]

list2 = [2, 4, 6]

print(merge_sorted_lists(list1, list2))  # Output: [1, 2, 3, 4, 5, 6]

Conclusion: 

Preparing for a Python interview involves understanding not only the basics of the language but also its advanced concepts and practical applications. By familiarizing yourself with these common questions and their answers, you can approach your interview with confidence. Remember, interviewers are often looking for how you think and solve problems, so clear explanations and demonstrating your thought process can be as important as getting the right answer. Good luck!