Python Interview Questions and Answers for 7 years experience

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

   • Answer: Lists are mutable (changeable) and ordered sequences, while tuples are immutable (unchangeable) and ordered sequences. Lists are defined using square brackets `[]`, and tuples using parentheses `()`. Lists are generally used when you need to modify the collection of items, while tuples are better for representing fixed collections of items, potentially improving performance and data integrity.

2. Explain the concept of decorators in Python.

   • Answer: Decorators are a powerful and expressive feature in Python that allows you to modify or enhance functions and methods in a clean and readable way. They are essentially functions that take another function as input, add functionality (like logging, timing, or access control), and return a modified function. This is achieved using the `@` symbol.

3. How do you handle exceptions in Python?

   • Answer: Python uses `try...except` blocks to handle exceptions. The `try` block contains the code that might raise an exception, and the `except` block specifies how to handle the exception if it occurs. You can specify specific exception types to catch, or use a generic `except Exception:` to catch any exception. `finally` blocks can be used to execute code regardless of whether an exception occurred.

4. What are generators in Python and how are they useful?

   • Answer: Generators are a special type of iterator that produce values on demand, rather than generating all values at once. They use the `yield` keyword instead of `return`. This makes them memory-efficient for handling large datasets, as they only generate the next value when requested. They are particularly useful for processing large files or streams of data.

5. Explain the difference between shallow copy and deep copy.

   • Answer: A shallow copy creates a new object, but it populates it with references to the elements of the original object. Changes to mutable elements in the copied object will affect the original object. A deep copy creates a completely independent copy of the original object, including all its nested objects. Changes to the copied object will not affect the original.

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

   • Answer: The GIL is a mechanism in CPython (the standard Python implementation) that allows only one native thread to hold control of the Python interpreter at any one time. This limits true parallelism for multi-threaded CPU-bound tasks. However, it doesn't affect I/O-bound tasks or multiprocessing.

7. How do you use lambda functions in Python?

   • Answer: Lambda functions are anonymous, small, single-expression functions defined using the `lambda` keyword. They are useful for short, simple operations that don't require a full function definition. They are often used with higher-order functions like `map`, `filter`, and `reduce`.

8. Explain the concept of object-oriented programming (OOP) in Python.

   • Answer: OOP is a programming paradigm based on the concept of "objects," which can contain data (attributes) and code (methods) that operate on that data. Key principles include encapsulation, inheritance, and polymorphism. Python supports OOP through classes and objects.

9. What are the different ways to create a class in Python?

   • Answer: A class is created using the `class` keyword followed by the class name and a colon. Attributes are defined within the class, and methods (functions within the class) operate on those attributes. You can also use inheritance to create subclasses that inherit attributes and methods from a parent class.

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