Python Basics Interview Questions

1. What is Python?

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

2. What are the key features of Python?

• Easy to learn and read
• Interpreted language
• Dynamically typed
• Object-oriented
• Extensive standard library
• Cross-platform compatibility
• Large community support

3. What is the difference between Python 2 and Python 3?

Key differences include:

• Print function syntax
• Integer division
• String handling
• Unicode support
• Exception handling
• Input function
• Range function

4. What are Python’s data types?

Basic data types:

• Numbers (int, float, complex)
• Strings
• Booleans
• None

Compound data types:

• Lists
• Tuples
• Sets
• Dictionaries

5. What is the difference between a list and a tuple?

Lists:

• Mutable
• Created using []
• Slower than tuples
• More memory intensive

Tuples:

• Immutable
• Created using ()
• Faster than lists
• Less memory intensive

6. What is a dictionary in Python?

A dictionary is a collection of key-value pairs. It’s unordered, mutable, and indexed by keys.

# Creating a dictionary
my_dict = {'name': 'John', 'age': 30}

# Accessing values
print(my_dict['name'])  # Output: John

# Adding new key-value pairs
my_dict['city'] = 'New York'

7. What are Python decorators?

Decorators are functions that modify the behavior of other functions. They use the @decorator syntax.

def my_decorator(func):
    def wrapper():
        print("Before function call")
        func()
        print("After function call")
    return wrapper

@my_decorator
def say_hello():
    print("Hello!")

8. What is the difference between is and == in Python?

• is checks if two objects have the same identity (same memory location)
• == checks if two objects have the same value

a = [1, 2, 3]
b = [1, 2, 3]

print(a == b)  # True
print(a is b)  # False

9. What are Python generators?

Generators are functions that return an iterator using yield. They generate values on-the-fly instead of storing them in memory.

def count_up_to(n):
    i = 0
    while i <= n:
        yield i
        i += 1

# Using the generator
for num in count_up_to(5):
    print(num)

10. What is the Global Interpreter Lock (GIL)?

The GIL is a mutex that protects access to Python objects, preventing multiple threads from executing Python bytecodes at once. This means Python’s threading is limited for CPU-bound tasks but works well for I/O-bound tasks.

11. What are Python’s built-in functions?

Common built-in functions include:

• print()
• len()
• type()
• int()
• str()
• list()
• dict()
• set()
• tuple()
• range()

12. What is the difference between shallow copy and deep copy?

Shallow copy:

• Creates a new object but references the same nested objects
• Use copy() method or [:] slicing

Deep copy:

• Creates a new object and recursively copies all nested objects
• Use deepcopy() from the copy module

import copy

# Shallow copy
list1 = [1, [2, 3], 4]
list2 = list1.copy()

# Deep copy
list3 = copy.deepcopy(list1)

13. What are Python’s naming conventions?

• Use lowercase for variables and functions
• Use uppercase for constants
• Use CamelCase for classes
• Use underscore_case for function and variable names
• Prefix private attributes with underscore
• Use double underscore for name mangling

14. What is the difference between append() and extend() in lists?

• append() adds a single item to the end of a list
• extend() adds all items from an iterable to the end of a list

list1 = [1, 2, 3]
list2 = [4, 5]

list1.append(list2)
print(list1)  # [1, 2, 3, [4, 5]]

list1.extend(list2)
print(list1)  # [1, 2, 3, 4, 5]

15. What is the difference between pass, continue, and break?

• pass: Does nothing, used as a placeholder
• continue: Skips the rest of the current iteration
• break: Exits the loop entirely

# pass example
def my_function():
    pass  # To be implemented later

# continue example
for i in range(5):
    if i == 2:
        continue
    print(i)  # Prints: 0, 1, 3, 4

# break example
for i in range(5):
    if i == 2:
        break
    print(i)  # Prints: 0, 1

What is the difference between is and ==?

• == compares the values of two objects.
• is compares the identity (memory address) of two objects.

Example:

a = [1, 2, 3]
b = [1, 2, 3]
c = a

print(a == b)  # True (same values)
print(a is b)  # False (different objects)
print(a is c)  # True (same object)

What is the difference between list, tuple, and set?

• List: Ordered, mutable, allows duplicates.
• Tuple: Ordered, immutable, allows duplicates.
• Set: Unordered, mutable, does not allow duplicates.

What is the difference between append() and extend() in lists?

• append() adds a single item to the end of a list.
• extend() adds all items from an iterable to the end of a list.

Example:

list1 = [1, 2, 3]
list2 = [4, 5, 6]

list1.append(list2)
print(list1)  # [1, 2, 3, [4, 5, 6]]

list1 = [1, 2, 3]  # Reset list1
list1.extend(list2)
print(list1)  # [1, 2, 3, 4, 5, 6]

What is a lambda function?

A lambda function is a small anonymous function defined with the lambda keyword. It can have any number of arguments but can only have one expression.

Example:

add = lambda x, y: x + y
print(add(2, 3))  # 5

What is the difference between *args and **kwargs?

• *args allows a function to accept any number of positional arguments.
• **kwargs allows a function to accept any number of keyword arguments.

Example:

def example_function(*args, **kwargs):
    print("Positional arguments:", args)
    print("Keyword arguments:", kwargs)

example_function(1, 2, 3, a=4, b=5)
# Positional arguments: (1, 2, 3)
# Keyword arguments: {'a': 4, 'b': 5}

What is the difference between range() and `