Question 1

What is Python?

Accepted Answer

Python is a widely-used, high-level, general-purpose, interpreted programming language designed with an emphasis on code readability and simplicity, allowing developers to express complex concepts in fewer lines of code. Created by Guido van Rossum in 1991 and maintained by the Python Software Foundation, Python supports multiple paradigms including Object-Oriented, Functional, and Procedural programming. It is extensively applied in web development, automation scripting, data science, artificial intelligence, game development, and system administration.

Question 2

What are the benefits of using Python language as a tool in the present scenario?

Accepted Answer

Python offers significant corporate and developmental benefits, including a clean and highly readable syntax, a massive 'batteries-included' standard library, cross-platform portability, multi-paradigm design patterns, and an unmatched ecosystem for automation, testing, and AI/ML. Python increases developer productivity: writing code takes fewer lines compared to Java or C++. Its massive standard library and third-party index (PyPI) contain pre-built solutions for nearly any task. Furthermore, its ease of integration with lower-level languages like C/C++ allows performance-critical modules to be optimized under the hood.

Question 3

Is Python a compiled language or an interpreted language?

Accepted Answer

Python is a hybrid language: it is partially compiled and partially interpreted. When we run a Python script, the source code is first compiled transparently into intermediate bytecode (`.pyc` files), which is then interpreted and executed on the target machine by the Python Virtual Machine (PVM). This compilation pass checks for basic syntax errors and generates a platform-independent bytecode. The PVM then acts as the interpreter, translating this bytecode into native machine instructions on the fly for the specific operating system and CPU running the application.

Question 4

What is the purpose of the '#' symbol in Python?

Accepted Answer

The '#' symbol is used in Python to declare a single-line comment. Any text or code placed after the '#' symbol on that line is ignored by the Python compiler and interpreter. Comments are vital for explaining code logic, documenting design decisions, or temporarily disabling lines of code during debugging. PEP 8 guidelines recommend using a single space after the '#' symbol for readability.

Question 5

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

Accepted Answer

Mutable data types can be modified or edited in-place at runtime without changing their memory address. Immutable data types cannot be modified once created; any edit operation creates a brand new object in memory at a different address. Understanding mutability is critical for managing data references and preventing side-effects. 
- **Mutable Types**: `list`, `dict`, `set`.
- **Immutable Types**: `int`, `float`, `string`, `tuple`, `frozenset`, `bool`.

Question 6

How are arguments passed in Python?

Accepted Answer

Python uses a mechanism called **Pass-by-Object-Reference** (also referred to as Call-by-Sharing or Call-by-Assignment). Variable names are pointers that bind to physical objects in memory, and passing arguments binds the function parameters to the exact same objects. The behavior depends entirely on whether the object is mutable or immutable:
1. **Mutable Objects (Lists, Dicts, Sets)**: Modifying the object inside the function modifies it in-place, affecting the caller directly.
2. **Immutable Objects (Ints, Strings, Tuples)**: Attempting to modify the variable inside the function rebinds the local parameter to a brand new object in memory, leaving the caller's original variable completely unchanged.

Question 7

What is the difference between a Set and Dictionary?

Accepted Answer

A Set is an unordered collection of unique, hashable elements with no duplicate values. A Dictionary is an unordered (ordered by insertion since Python 3.7) collection of key-value pairs used to map unique keys to specific data values. Under the hood, both data types rely on hash tables for near-instantaneous search and lookup speeds (O(1) average time complexity). A Set can be thought of as a dictionary that stores only unique keys without any associated values.

Question 8

What is List Comprehension? Give an Example.

Accepted Answer

List comprehension is a concise, expressive syntactic construction that provides a short, readable way to create a new list based on an existing iterable or list structure. List comprehensions replace verbose `for` loops and element appending steps into a single line of code. They are highly optimized in Python and run faster than standard loops because they are executed at C-speed inside the interpreter.

Question 9

What is a lambda function?

Accepted Answer

A lambda function in Python is a small, anonymous, single-statement helper function that can accept any number of parameters but can only evaluate and return a single expression. Lambda functions are defined using the `lambda` keyword instead of the standard `def` keyword. They are typically used for inline, short-lived operations where writing a full function definition would be redundant, especially alongside higher-order operations like `map()`, `filter()`, or `sorted()`.

Question 10

What is a pass in Python?

Accepted Answer

The `pass` statement in Python is a null operation statement. It is used as a syntactic placeholder in compound blocks (like functions, loops, or classes) where the interpreter requires a statement to be present, but the developer does not want to execute any code. Because Python structures block scopes using indentation rather than curly braces, leaving an empty block (e.g., a function header without a body) will result in a severe IndentationError. The `pass` statement satisfies this block requirement cleanly while executing absolutely nothing.

Question 11

What is the difference between / and // in Python?

Accepted Answer

The operator `/` performs precise decimal division and always returns a floating-point result (even if the division is even). The operator `//` performs floor division, rounding the division result down to the nearest whole integer. 1. **Precise Division (`/`)**: Evaluates complete division. For example, `5 / 2` evaluates to `2.5`.
2. **Floor Division (`//`)**: Divides and rounds down towards negative infinity, returning the largest integer smaller than or equal to the quotient. For example, `5 // 2` evaluates to `2`, and `-5 // 2` evaluates to `-3`.

Question 12

How is Exceptional handling done in Python?

Accepted Answer

Exception handling in Python is managed using four core keywords inside structured blocks: `try`, `except`, `else`, and `finally`. 1. **`try`**: The block of code monitored for potential errors.
2. **`except`**: Catches and resolves specific exception instances raised in the try block.
3. **`else`**: Executes only if the code in the try block runs successfully without throwing any errors.
4. **`finally`**: Executes under all conditions, making it ideal for performing critical cleanups (e.g. closing files or DB connections).

Question 13

What is a swapcase function in Python?

Accepted Answer

The `swapcase()` function is a built-in string method in Python that returns a new copy of the target string where all uppercase alphabetical characters are converted to lowercase, and all lowercase characters are converted to uppercase. Because strings in Python are strictly immutable, `swapcase()` does not modify the original string variable in-place; instead, it generates and returns a new string object containing the swapped cases.

Question 14

What is the difference between a for loop and a while loop in Python?

Accepted Answer

A `for` loop is designed to iterate through a pre-defined sequence or collection (like lists, tuples, or ranges) where the iteration count is known beforehand. A `while` loop repeatedly executes code as long as a specified boolean condition remains true. 1. **`for` Loop**: Preferred for iterating over finite datasets, collections, or structured intervals. It handles iteration automatically behind the scenes using Python's Iterator Protocol.
2. **`while` Loop**: Used when execution must continue until a dynamic condition shifts (e.g. listening to sockets, processing queues, or waiting for user actions). It requires manual state increments inside the loop to avoid infinite execution.

Question 15

Can we pass a function as an argument in Python?

Accepted Answer

Yes. In Python, functions are 'first-class citizens', meaning they are treated like standard object variables. They can be assigned to variables, stored inside data collections, passed as arguments to other functions, or returned from functions. Functions that accept other functions as arguments, or return functions, are called **Higher-Order Functions**. This capability is extremely powerful and forms the foundation of Python decorators, mapping utilities, and callback systems.

Python Foundations Interview Prep Portal

What is Python?

What are the benefits of using Python language as a tool in the present scenario?

Is Python a compiled language or an interpreted language?

What is the purpose of the '#' symbol in Python?

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

How are arguments passed in Python?

What is the difference between a Set and Dictionary?

What is List Comprehension? Give an Example.

What is a lambda function?

What is a pass in Python?

What is the difference between / and // in Python?

How is Exceptional handling done in Python?

What is a swapcase function in Python?

What is the difference between a for loop and a while loop in Python?

Can we pass a function as an argument in Python?

What are *args and **kwargs?

Is Indentation Required in Python?

What is Scope in Python?

What is docstring in Python?

What is a dynamically typed language?

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

What are Built-in data types in Python?

How do you floor a number in Python?

What is the difference between xrange and range functions in Python?

What is Dictionary Comprehension? Give an Example.

Is Tuple Comprehension possible in Python? If yes, how, and if not why?

Differentiate between a List and a Tuple in Python.

What is the difference between a shallow copy and a deep copy?

Which sorting technique is used by sort() and sorted() functions of Python?

What are Decorators in Python?

How do you debug a Python program?

What are Iterators in Python?

What are Generators in Python?

Does Python support multiple inheritance?

What are Polymorphism and Encapsulation in Python?

What is garbage collection in Python?

How do you do data abstraction in Python?

How is memory management done in Python?

How do you delete a file using Python?

What is slicing in Python?

What is a namespace in Python?

What is PIP?

What is a zip function?

What are Pickling and Unpickling in Python?

How can we do Functional Programming in Python?

What is __init__() in Python?

Write a code to display the current system time in Python.

What are Access Specifiers in Python?

What are unit tests in Python?

What is the Python Global Interpreter Lock (GIL)?

What are Function Annotations in Python?

What are Exception Groups in Python?

Python Foundations
Interview Prep Portal

What is init() in Python?