Top Python Interview Questions and Answers #

1. What is Python? #

Python is a high-level, interpreted programming language known for its readability and simplicity. It emphasizes code readability and allows developers to express concepts in fewer lines of code compared to other programming languages.

2. What are the key features of Python? #

• Readability: Python code is easy to read and maintain due to its clear syntax.
• Dynamic Typing: Variables are not explicitly declared and can change types during execution.
• Interpreted Nature: Python code is executed line by line by the Python interpreter.
• Cross-platform: Python is available on various platforms, making it portable.
• Large Standard Library: Python includes a comprehensive library for various tasks.
• Community and Ecosystem: Python has a strong community and a wide range of libraries and frameworks.

3. How do you comment in Python? #

Python supports single-line comments using the # symbol. Multi-line comments are usually enclosed in triple quotes (''' or """).

Example:

# This is a single-line comment

'''
This is a multi-line comment.
It can span multiple lines.
'''

4. Explain Python’s indentation. #

Python uses indentation (whitespace at the beginning of a line) to define the scope and structure of code blocks. Consistent indentation is crucial, as it replaces the traditional curly braces used in other programming languages.

Example:

if x > 0:
    print("x is positive")
else:
    print("x is non-positive")

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

Python has several built-in data types, including:

• Integers (int)
• Floating-point numbers (float)
• Strings (str)
• Lists (list)
• Tuples (tuple)
• Sets (set)
• Dictionaries (dict)
• Booleans (bool)

6. How do you create a function in Python? #

You can define a function in Python using the def keyword followed by the function name and parameters.

Example:

def greet(name):
    print(f"Hello, {name}!")

greet("Alice")

7. Explain the difference between a list and a tuple. #

• List: Lists are mutable and can be modified after creation. They are defined using square brackets [].

• Tuple: Tuples are immutable and cannot be modified after creation. They are defined using parentheses ().

8. How do you handle exceptions in Python? #

Python uses a try...except block to handle exceptions. Code that might raise an exception is placed in the try block, and the handling code is placed in the except block.

Example:

try:
    result = 10 / 0
except ZeroDivisionError:
    print("Error: Division by zero")

9. What is a virtual environment in Python? #

A virtual environment is an isolated environment for Python projects. It allows you to install packages separately for different projects, avoiding conflicts between dependencies.

10. How can you iterate over a dictionary in Python? #

You can use a for loop to iterate over the keys of a dictionary. To access both keys and values, you can use the items() method.

Example:

my_dict = {"a": 1, "b": 2, "c": 3}
for key in my_dict:
    print(key, my_dict[key])

# Using items() method
for key, value in my_dict.items():
    print(key, value)

11. Explain the concept of list comprehension. #

List comprehension is a concise way to create lists in Python. It combines a for loop and an expression into a single line.

Example:

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

12. How do you open and read files in Python? #

You can use the open() function to open files and the read() or readlines() methods to read their content.

Example:

with open("example.txt", "r") as file:
    content = file.read()
    # or
    lines = file.readlines()

13. What is a decorator in Python? #

A decorator is a higher-order function that allows you to modify or extend the behavior of other functions or methods. It is often used for adding additional functionality to functions without modifying their code.

14. How do you define a class in Python? #

You can define a class in Python using the class keyword, followed by the class name and a colon. Inside the class, you can define attributes and methods.

Example:

class Dog:
    def __init__(self, name):
        self.name = name
    
    def bark(self):
        print(f"{self.name} says Woof!")

15. Explain the concept of inheritance in Python. #

Inheritance is a fundamental concept in object-oriented programming (OOP) that allows a class to inherit attributes and methods from another class. The class that inherits from another class is called the subclass or derived class, while the class being inherited from is called the superclass or base class.

Example:

class Animal:
    def speak(self):
        pass

class Dog(Animal):
    def speak(self):
        print("Woof!")

class Cat(Animal):
    def speak(self):
        print("Meow!")