Python Interview Questions and Answers

 Python Interview Questions and Answers

1. What is Python?

Python is a high-level, interpreted programming language known for its simplicity and readability. It emphasizes code readability with its clean syntax and supports multiple programming paradigms, including procedural, object-oriented, and functional programming.

2. What are the key features of Python?

Some key features of Python include:

• Easy-to-read syntax
• Dynamic typing and automatic memory management
• Support for multiple programming paradigms
• Extensive standard library
• Strong community support

3. How do you comment out a line in Python?

You can comment out a line in Python using the "#" symbol. Anything after "#" in a line is considered a comment and is not executed.

4. What are the differences between lists and tuples in Python?

Lists and tuples are both sequence types in Python, but there are some key differences:

• Lists are mutable, meaning you can modify them after creation, while tuples are immutable.
• Lists use square brackets ([]), while tuples use parentheses ().
• Lists have more built-in methods compared to tuples.

5. What is the difference between '==' and 'is' in Python?

The '==' operator checks for equality between two objects based on their values, while the 'is' operator checks if two objects refer to the same memory location, i.e., if they are the same object.

6. What is the purpose of 'self' in Python?

In Python class methods, 'self' refers to the instance of the class. It is used to access and modify instance variables and call other methods within the class.

7. What is a decorator in Python?

A decorator is a design pattern in Python that allows you to modify the behavior of a function or class without changing its source code. Decorators are represented using the '@' symbol and placed above the function or class they modify.

8. What are the main differences between a shallow copy and a deep copy?

A shallow copy creates a new object that references the original object's elements, while a deep copy creates a completely independent copy of the object and its elements. Modifying the original object's elements will affect the shallow copy, but not the deep copy.

9. Explain the concept of a generator in Python.

A generator is a type of iterator that generates a sequence of values on-the-fly using the 'yield' keyword. Unlike lists or tuples, generators do not store all values in memory at once, making them memory-efficient for large datasets.

10. How can you handle exceptions in Python?

In Python, exceptions are handled using the 'try-except' block. The code that might raise an exception is placed inside the 'try' block, and the exception handling logic is placed inside the 'except' block. If an exception occurs, the code inside the 'except' block is executed.

11. What are the different ways to iterate over a list in Python?

There are several ways to iterate over a list in Python, including:

Using a for loop: 'for an item in my_list:'

Using a while loop with an index: 'index = 0; while index < len(my_list):'

Using the enumerate() function: 'for index, item in enumerate(my_list):'

12. What is the purpose of the 'pass' statement in Python?

The 'pass' statement is a placeholder statement in Python that does nothing. It is used when a statement is required syntactically but no action is needed. It allows you to have an empty block of code without causing any errors.

13. Explain the concept of a virtual environment in Python.

A virtual environment is a self-contained directory that contains a specific Python interpreter and its installed packages. It allows you to isolate your project's dependencies from other projects, ensuring that each project uses its own set of packages and versions.

14. How can you handle file input/output operations in Python?

Python provides the 'open()' function to handle file input/output operations. 

To open a file for reading, you can use: file = open("filename.txt", "r"). 

For writing, you can use: file = open("filename.txt", "w"). 

After you're done with the file, remember to close it using: file.close().

15. What is a lambda function in Python?

A lambda function, also known as an anonymous function, is a small and anonymous function that doesn't require a formal def statement. It is typically used for simple, one-line operations and is defined using the 'lambda' keyword. Example: square = lambda x: x**2.

16. How do you handle modules and packages in Python?

Modules are files containing Python code, while packages are directories that contain multiple modules. To use a module or package in Python, you can import it using the 'import' statement. For example: import module_name or from package_name import module_name.

17. How can you sort a list in Python?

You can sort a list in Python using the 'sort()' method, which sorts the list in-place, or by using the 'sorted()' function, which returns a new sorted list without modifying the original one. Example: my_list.sort() or sorted_list = sorted(my_list).

18. What is the Global Interpreter Lock (GIL) in Python?

The Global Interpreter Lock (GIL) is a mechanism in CPython (the reference implementation of Python) that ensures only one thread executes Python bytecode at a time. This means that even in a multi-threaded Python program, only one thread can execute Python code at any given time, limiting true parallelism.

19. Explain the concept of recursion in Python.

Recursion is a programming technique where a function calls itself to solve a problem by breaking it down into smaller, similar subproblems. It involves two main components: the base case (the terminating condition) and the recursive case (the function calling itself with smaller inputs).

20. How can you handle database operations in Python?

Python provides various libraries to handle database operations, such as SQLite, MySQL, or PostgreSQL. You can use libraries like 'sqlite3', 'MySQL-connector-python', or 'psycopg2' to establish a connection to the database, execute queries, and fetch results.

Also Read: Common Interview Q & A.