20+ Python Interview Questions

1. What is Python? List some key features.

Python is an interpreted, high-level, general-purpose programming language known for its simplicity and readability. Key features include:

• Easy to read and write: Python has a simple syntax.

• Interpreted language: Code is executed line by line.

• Dynamically typed: No need to declare data types.

• Extensive libraries: Supports a wide range of libraries for various tasks (e.g., NumPy, Pandas, TensorFlow).

• Cross-platform: Runs on various platforms like Windows, macOS, and Linux.

2. What are Python’s built-in data types?

Python supports several built-in data types:

• Numeric types: int, float, complex

• Sequence types: list, tuple, range

• Text type: str

• Mapping type: dict

• Set types: set, frozenset

• Boolean type: bool

• Binary types: bytes, bytearray, memoryview

3. 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 helps in:

• Making the code more readable.

• Improving code consistency.

• Ensuring code quality in collaborative environments.

Introduction to Python Programming

Python, the beloved snake in the programming world, has slithered its way to the top of the list as one of the most popular languages used in software development today. Whether you are just starting your coding journey or you are a seasoned developer, chances are you’ve encountered Python’s clean, readable syntax and extensive libraries.

Python’s ease of use and versatility make it the go-to language for a wide variety of applications, ranging from web development with Django and Flask, data analysis with Pandas, machine learning with Scikit-learn, to automation tasks and even AI research. Its simple syntax emphasizes readability, reducing the cost of program maintenance and allowing you to focus more on solving problems rather than understanding complex code.

In the tech job market, Python is in high demand. If you’re preparing for a Python developer interview, being well-versed in Python basics and core concepts is crucial. To help you prepare, we’ve put together a comprehensive list of 20+ essential Python interview questions that cover the fundamentals, advanced topics, and coding exercises. This guide is designed to test your understanding and give you the confidence to ace your next Python interview.

What to Expect in a Python Interview?

Python interviews can vary based on the role you are applying for (e.g., data analyst, backend developer, AI/ML engineer). However, there are certain core topics that interviewers commonly explore:

1. Basic Syntax and Data Types: You’ll be expected to know Python’s basic syntax, variable types, and built-in functions.

2. Object-Oriented Programming (OOP): Concepts like classes, inheritance, and polymorphism are often discussed.

3. Data Structures: A strong grasp of lists, dictionaries, sets, and tuples is essential.

4. Advanced Topics: This can include questions on generators, decorators, context managers, and error handling.

5. Problem-Solving Skills: Coding challenges are a common part of the process, where you might be asked to solve algorithm-based problems using Python.

In this blog post, we’ll cover Python interview questions across a range of difficulty levels, so whether you’re a beginner or an experienced developer, you’ll find this guide helpful.

Basic Python Questions

9. How do you handle exceptions in Python?

Python uses try, except, else, and finally blocks for exception handling.

Output:

10. What is the difference between append() and extend() methods in Python?

• append(): Adds its argument as a single element at the end of the list.

• extend(): Iterates over its argument, adding each element to the list.

11. How do you swap two variables in Python without using a temporary variable?

Python allows you to swap variables in a single line using tuple unpacking.

12. How can you check if a string contains only digits?

You can use the .isdigit() method.

13. What is the difference between remove(), pop(), and del in Python?

• remove(value): Removes the first occurrence of the value.

• pop(index): Removes and returns the element at the given index (default is the last element).

• del: Deletes the element at the specified index or deletes the entire list.

4. Is Python a compiled language or an interpreted language?

Actually, Python is a partially compiled language and partially interpreted language. The compilation part is done first when we execute our code and this will generate byte code internally this byte code gets converted by the Python virtual machine(p.v.m) according to the underlying platform(machine+operating system).

5. What is the difference between a Mutable datatype and an Immutable data type?

• Mutable data types can be edited i.e., they can change at runtime. Eg – List, Dictionary, etc.

• Immutable data types can not be edited i.e., they can not change at runtime. Eg – String, Tuple, etc.

6. How are arguments passed by value or by reference in Python?

Everything in Python is an object and all variables hold references to the objects. The reference values are according to the functions; as a result, you cannot change the value of the references. However, you can change the objects if it is mutable.

7. What is the difference between a Set and Dictionary?

• The set is an unordered collection of data types that is iterable, mutable and has no duplicate elements.

• A dictionary in Python is an ordered collection of data values, used to store data values like a map.

8. What are args and *kwargs?

To pass a variable number of arguments to a function in Python, use the special syntax args and *kwargs in the function specification. Both are to send a variable-length argument list. The syntax *args is used to pass a non-keyworded, variable-length argument list.

14. What is Scope in Python?

The location where we can find a variable and also access it if required is called the scope of a variable.

• Python Local variable: Local variables are those that are initialized within a function and are unique to that function. It cannot be accessed outside of the function.

• Python Global variables: Global variables are the ones that are defined and declared outside any function and are not specified to any function.

• Module-level scope: It refers to the global objects of the current module accessible in the program.

• Outermost scope: It refers to any built-in names that the program can call. The name referenced is located last among the objects in this scope.

15. What is docstring in Python?

Python documentation strings (or docstrings) provide a convenient way of associating documentation with Python modules, functions, classes, and methods.

• Declaring Docstrings: The docstrings are declared using ”’triple single quotes”’ or “””triple double quotes””” just below the class, method, or function declaration. All functions should have a docstring.

• Accessing Docstrings: The docstrings can be accessed using the doc method of the object or using the help function.

16. What is a break, continue, and pass in Python?

• The break statement is used to terminate the loop or statement in which it is present. After that, the control will pass to the statements that are present after the break statement, if available.

• Continue is also a loop control statement just like the break statement. continue statement is opposite to that of the break statement, instead of terminating the loop, it forces to execute the next iteration of the loop.

• Pass means performing no operation or in other words, it is a placeholder in the compound statement, where there should be a blank left and nothing has to be written there.

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

• List: Mutable, can be changed after creation. Defined with square brackets [].

• Tuple: Immutable, cannot be changed after creation. Defined with parentheses ().

Intermediate Python Questions

1. What is a lambda function in Python?

A lambda function is an anonymous function defined with the lambda keyword. It can take any number of arguments but only has one expression.

2. Explain list comprehension with an example.

List comprehension provides a concise way to create lists using a single line of code.

3. What is the difference between deepcopy() and copy() in Python?

• copy() creates a shallow copy, copying only the outer object, not nested objects.

• deepcopy() creates a deep copy, copying all nested objects as well.

4. What is the purpose of self in Python classes?

self refers to the instance of the class. It is used to access variables and methods within the class.

5. What are Python generators and how do they work?

Generators are functions that use yield to return an iterable sequence of values, one at a time.

Output:

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