Python Interview Preparation Guide - 100 Essential Questions

🎯 Section 1: Python Basics (Questions 1-5)

Q1: What is Python and what are its key features?

Python is a high-level, interpreted programming language known for its simplicity and readability.

Key Features:

Easy to learn and use: Simple, readable syntax
Interpreted language: No compilation step needed
Object-oriented: Supports OOP programming paradigms
Extensive standard library: Rich set of built-in modules
Cross-platform compatibility: Runs on multiple operating systems
Dynamic typing: Variables don't need explicit type declaration
Large community support: Active community and extensive documentation

Q2: What are the differences between Python 2 and Python 3?

Feature	Python 2	Python 3
Print Statement	print "Hello"	print("Hello")
Unicode Support	ASCII by default	Unicode by default
Integer Division	3/2 = 1	3/2 = 1.5
Range Function	range() and xrange()	range() only
Exception Handling	except Exception, e:	except Exception as e:
Input Function	raw_input() for strings	input() returns strings

Q3: Is Python a good programming language for beginners? Why?

Yes, Python is excellent for beginners because:

Simple and readable syntax: Resembles natural language
No complex memory management: Automatic garbage collection
Extensive documentation: Well-documented with tutorials
Large community support: Active forums and help resources
Interactive shell: REPL for immediate feedback
Fewer lines of code: Express concepts concisely

Q4: What are Python's major use cases?

Web development: Django, Flask, FastAPI
Data science and analytics: NumPy, Pandas, Matplotlib
Machine learning and AI: TensorFlow, PyTorch, scikit-learn
Automation and scripting: Task automation, system administration
Desktop applications: Tkinter, PyQt, Kivy
Game development: Pygame, Panda3D
Scientific computing: SciPy, SymPy

Q5: Name some organizations that use Python.

Major organizations using Python include: Google, Netflix, Instagram, Spotify, Dropbox, Reddit, NASA, Mozilla, IBM, Facebook, YouTube, Pinterest, Uber, and many others across various industries.

📊 Section 2: Variables and Data Types (Questions 6-15)

Q6: What are Python variable naming rules?

Must start with: Letter (a-z, A-Z) or underscore (_)
Can contain: Letters, numbers, and underscores
Case-sensitive: 'age' and 'Age' are different variables
Cannot use: Python keywords (if, for, class, etc.)
Should be descriptive: Use meaningful names

Q7: What is the difference between local and global variables?

Variable Type	Scope	Access
Local Variables	Inside a function only	Only within that function
Global Variables	Throughout the program	From anywhere in the program

Use global keyword to modify global variables inside functions.

Q8: What are Python's basic data types?

Numbers: int, float, complex
Boolean: bool (True/False)
Strings: str
Lists: mutable ordered collections
Tuples: immutable ordered collections
Sets: unordered collections of unique elements
Dictionaries: key-value pairs

Q9: How do you swap variables in Python?

# Method 1: Tuple unpacking (Pythonic)
a, b = 10, 20
a, b = b, a
print(f"a = {a}, b = {b}")  # a = 20, b = 10

# Method 2: Using temporary variable
temp = a
a = b
b = temp
                        

Q10: What is multiple assignment in Python?

Assigning values to multiple variables in one statement:

a, b, c = 1, 2, 3
x = y = z = 0
                        

Q11: What are Python operators?

Arithmetic: +, -, *, /, //, %, **
Assignment: =, +=, -=, *=, etc.
Comparison: ==, !=, <, >, <=, >=
Logical: and, or, not

Q12: What is type casting in Python?

Converting one data type to another:

int("123")    # String to integer
float(42)     # Integer to float
str(123)      # Integer to string
list((1,2,3)) # Tuple to list
                        

Q13: How do you take user input in Python?

name = input("Enter your name: ")
age = int(input("Enter your age: "))
                        

Q14: What is the difference between == and is operators?

==: compares values
is: compares object identity (memory location)

Q15: What are complex numbers in Python?

Numbers with real and imaginary parts:

z = 3 + 4j
print(z.real)  # 3.0
print(z.imag)  # 4.0
                        

🔤 Section 3: Strings (Questions 16-25)

Q16: How do you create strings in Python?

single_quote = 'Hello'
double_quote = "World"
triple_quote = """Multi-line
string"""
                        

Q17: Are Python strings mutable?

No, Python strings are immutable. You cannot change individual characters, but you can create new strings.

Q18: What are common string methods?

len(): Length of string
upper(), lower(): Case conversion
strip(): Remove whitespace
split(): Split into list
replace(): Replace substring
find(), index(): Find substring position

Q19: How do you concatenate strings?

# Method 1: + operator
result = "Hello" + " " + "World"

# Method 2: join() method
result = " ".join(["Hello", "World"])

# Method 3: f-strings
name = "World"
result = f"Hello {name}"
                        

Q20: What is string slicing?

Extracting parts of a string:

text = "Hello World"
print(text[0:5])   # "Hello"
print(text[:5])    # "Hello"
print(text[6:])    # "World"
print(text[-5:])   # "World"
                        

Q21: How do you check if a character exists in a string?

text = "Hello World"
if 'o' in text:
    print("Found")
                        

Q22: What is the difference between find() and index()?

find(): Returns -1 if substring not found
index(): Raises ValueError if substring not found

Q23: How do you reverse a string?

text = "Hello"
reversed_text = text[::-1]  # "olleH"
                        

Q24: What are escape characters in strings?

Special characters preceded by backslash:

\n: Newline
\t: Tab
\": Double quote
\': Single quote
\\: Backslash

Q25: How do you format strings in Python?

# Old style
"Hello %s" % name

# .format() method
"Hello {}".format(name)

# f-strings (Python 3.6+)
f"Hello {name}"
                        

🔄 Section 4: Control Statements (Questions 26-35)

Q26: What are the types of conditional statements in Python?

if statement
if-else statement
elif (else if) statement
Nested if statements

Q27: How do you write a single-line if statement?

result = "positive" if x > 0 else "non-positive"

Q28: What operators can be used in if statements?

Comparison operators: ==, !=, <, >, <=, >=
Logical operators: and, or, not
Membership operators: in, not in
Identity operators: is, is not

Q29: What is a nested if statement?

An if statement inside another if statement:

if x > 0:
    if x > 10:
        print("Greater than 10")
    else:
        print("Between 1 and 10")
                        

Q30: How do you use the 'and' operator in if statements?

age = 25
if age >= 18 and age <= 65:
    print("Working age")
                        

Q31: What are Python's loop types?

for loop: Iterates over sequences
while loop: Repeats while condition is true
Nested loops: Loops inside loops

Q32: How does the range() function work?

range(5)        # 0, 1, 2, 3, 4
range(1, 6)     # 1, 2, 3, 4, 5
range(0, 10, 2) # 0, 2, 4, 6, 8
                        

Q33: What are break and continue statements?

break: Exits the loop completely
continue: Skips current iteration, continues with next

Q34: What is a for-else loop?

The else block executes when the loop completes normally (not via break):

for i in range(5):
    print(i)
else:
    print("Loop completed")
                        

Q35: How do you iterate over multiple sequences?

# zip() function
names = ["Alice", "Bob"]
ages = [25, 30]
for name, age in zip(names, ages):
    print(f"{name}: {age}")
                        

⚙️ Section 5: Functions (Questions 36-45)

Q36: How do you define a function in Python?

def function_name(parameters):
    """Documentation string"""
    # Function body
    return value
                        

Q37: What are the types of function arguments?

No arguments: def func():
With arguments, no return: def func(a, b):
With arguments and return: def func(a, b): return a + b
No arguments with return: def func(): return "Hello"

Q38: What are default parameters?

Parameters with default values:

def greet(name, greeting="Hello"):
    return f"{greeting}, {name}!"
                        

Q39: What is the difference between arguments and parameters?

Parameters: Variables in function definition
Arguments: Actual values passed to function when called

Q40: What are *args and **kwargs?

*args: Variable number of positional arguments
**kwargs: Variable number of keyword arguments

def func(*args, **kwargs):
    print(args)     # Tuple
    print(kwargs)   # Dictionary
                        

Q41: What is a lambda function?

Anonymous functions defined with lambda keyword:

square = lambda x: x ** 2
add = lambda x, y: x + y
                        

Q42: What are higher-order functions?

Functions that take other functions as arguments or return functions:

map(): Apply function to all items
filter(): Filter items based on condition
reduce(): Apply function cumulatively

Q43: What is function documentation?

Docstrings describe what a function does:

def add(a, b):
    """
    Add two numbers and return the result.
    """
    return a + b
                        

Q44: What is variable scope in functions?

Local scope: Variables inside function
Global scope: Variables outside all functions
Built-in scope: Built-in names like print, len

Q45: What is recursion?

A function calling itself:

def factorial(n):
    if n <= 1:
        return 1
    return n * factorial(n - 1)
                        

📋 Section 6: Lists (Questions 46-55)

Q46: What is a list in Python?

A mutable, ordered collection of items that can store different data types:

my_list = [1, 2, "hello", 3.14, True]

Q47: What are common list methods?

append(): Add item to end
extend(): Add multiple items
insert(): Insert at specific position
remove(): Remove specific item
pop(): Remove and return item
index(): Find item position
count(): Count occurrences

Q48: How do you access list elements?

my_list = [1, 2, 3, 4, 5]
print(my_list[0])   # First element: 1
print(my_list[-1])  # Last element: 5
print(my_list[1:4]) # Slice: [2, 3, 4]
                        

Q49: How do you copy a list?

# Shallow copy
new_list = old_list.copy()
new_list = old_list[:]
new_list = list(old_list)

# Deep copy
import copy
new_list = copy.deepcopy(old_list)
                        

Q50: What is list comprehension?

Concise way to create lists:

squares = [x**2 for x in range(10)]
evens = [x for x in range(20) if x % 2 == 0]
                        

Q51: How do you use lists as stacks and queues?

Stack (LIFO):

stack = []
stack.append(1)  # Push
item = stack.pop()  # Pop
                        

Queue (FIFO):

from collections import deque
queue = deque([])
queue.append(1)      # Enqueue
item = queue.popleft()  # Dequeue
                        

Q52: What are nested lists?

Lists containing other lists:

matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
print(matrix[0][1])  # Access element: 2
                        

Q53: How do you search for elements in a list?

my_list = [1, 2, 3, 4, 5]
if 3 in my_list:
    position = my_list.index(3)
    print(f"Found at position {position}")
                        

Q54: How do you sort a list?

numbers = [3, 1, 4, 1, 5]
numbers.sort()  # In-place sorting
sorted_numbers = sorted(numbers)  # Return new sorted list
                        

Q55: How do you remove duplicates from a list?

# Using set (loses order)
unique_list = list(set(original_list))

# Preserving order
unique_list = []
for item in original_list:
    if item not in unique_list:
        unique_list.append(item)
                        

📦 Section 7: Tuples (Questions 56-60)

Q56: What is a tuple in Python?

An immutable, ordered collection of items:

my_tuple = (1, 2, 3, "hello")
single_item = (1,)  # Note the comma for single item
                        

Q57: How do you access tuple elements?

my_tuple = (1, 2, 3, 4, 5)
print(my_tuple[0])   # First element
print(my_tuple[-1])  # Last element
print(my_tuple[1:4]) # Slicing
                        

Q58: Can you modify tuples?

No, tuples are immutable. You cannot change, add, or remove items after creation.

Q59: How do you convert between tuples and lists?

# Tuple to list
my_list = list(my_tuple)

# List to tuple
my_tuple = tuple(my_list)
                        

Q60: What are tuple methods?

count(): Count occurrences of an element
index(): Find the index of an element
len(): Get the length of the tuple

🔢 Section 8: Sets (Questions 61-65)

Q61: What is a set in Python?

An unordered collection of unique elements:

my_set = {1, 2, 3, 4, 5}
empty_set = set()  # Note: {} creates a dictionary
                        

Q62: What are common set operations?

add(): Add single element
update(): Add multiple elements
remove(): Remove element (raises error if not found)
discard(): Remove element (no error if not found)
clear(): Remove all elements

Q63: What are set mathematical operations?

set1 = {1, 2, 3, 4}
set2 = {3, 4, 5, 6}

union = set1 | set2          # {1, 2, 3, 4, 5, 6}
intersection = set1 & set2   # {3, 4}
difference = set1 - set2     # {1, 2}
symmetric_diff = set1 ^ set2 # {1, 2, 5, 6}
                        

Q64: How do you check subset and superset relationships?

set1 = {1, 2}
set2 = {1, 2, 3, 4}

print(set1.issubset(set2))    # True
print(set2.issuperset(set1))  # True
                        

Q65: How do you iterate over a set?

my_set = {1, 2, 3, 4, 5}
for item in my_set:
    print(item)
                        

📚 Section 9: Dictionaries (Questions 66-75)

Q66: What is a dictionary in Python?

A mutable collection of key-value pairs:

my_dict = {"name": "Alice", "age": 30, "city": "New York"}

Q67: How do you access dictionary values?

# Method 1: Square brackets
name = my_dict["name"]

# Method 2: get() method (safer)
name = my_dict.get("name", "Unknown")
                        

Q68: How do you add/update dictionary items?

my_dict["email"] = "alice@email.com"  # Add new key
my_dict["age"] = 31                   # Update existing key
my_dict.update({"phone": "123-456"})  # Update multiple
                        

Q69: How do you remove items from a dictionary?

del my_dict["age"]                    # Remove specific key
removed_value = my_dict.pop("city", None)  # Remove and return
my_dict.clear()                       # Remove all items
                        

Q70: How do you iterate over a dictionary?

# Keys only
for key in my_dict:
    print(key)

# Values only
for value in my_dict.values():
    print(value)

# Key-value pairs
for key, value in my_dict.items():
    print(f"{key}: {value}")
                        

Q71: How do you check if a key exists in a dictionary?

if "name" in my_dict:
    print("Key exists")

# Or using get()
if my_dict.get("name") is not None:
    print("Key exists")
                        

Q72: How do you merge two dictionaries?

# Python 3.5+
merged = {**dict1, **dict2}

# Python 3.9+
merged = dict1 | dict2

# update() method
dict1.update(dict2)
                        

Q73: What are dictionary comprehensions?

squares = {x: x**2 for x in range(5)}
# Result: {0: 0, 1: 1, 2: 4, 3: 9, 4: 16}
                        

Q74: How do you sort a dictionary?

# Sort by keys
sorted_dict = dict(sorted(my_dict.items()))

# Sort by values
sorted_dict = dict(sorted(my_dict.items(), key=lambda x: x[1]))
                        

Q75: What is the difference between lists and dictionaries?

Lists: Ordered, indexed by integers, allow duplicates
Dictionaries: Ordered (Python 3.7+), indexed by keys, keys must be unique

📁 Section 10: File Handling (Questions 76-80)

Q76: How do you open and close files in Python?

# Method 1: Manual close
file = open("filename.txt", "r")
content = file.read()
file.close()

# Method 2: Using with statement (recommended)
with open("filename.txt", "r") as file:
    content = file.read()
                        

Q77: What are different file modes?

"r": Read mode (default)
"w": Write mode (overwrites existing)
"a": Append mode
"x": Exclusive creation mode
"b": Binary mode
"t": Text mode (default)

Q78: How do you read files in Python?

# Read entire file
with open("file.txt", "r") as f:
    content = f.read()

# Read line by line
with open("file.txt", "r") as f:
    for line in f:
        print(line.strip())

# Read all lines into list
with open("file.txt", "r") as f:
    lines = f.readlines()
                        

Q79: How do you write to files in Python?

# Write to file (overwrite)
with open("file.txt", "w") as f:
    f.write("Hello World")

# Append to file
with open("file.txt", "a") as f:
    f.write("New line\n")
                        

Q80: How do you handle file exceptions?

try:
    with open("file.txt", "r") as f:
        content = f.read()
except FileNotFoundError:
    print("File not found")
except IOError:
    print("Error reading file")
                        

🏗️ Section 11: Object-Oriented Programming (Questions 81-90)

Q81: What is a class and object in Python?

class Car:
    def __init__(self, brand, model):
        self.brand = brand
        self.model = model
    
    def start(self):
        return f"{self.brand} {self.model} is starting"

# Create object
my_car = Car("Toyota", "Camry")
print(my_car.start())
                        

Q82: What is the __init__ method?

The constructor method called when an object is created. It initializes object attributes.

Q83: What is inheritance in Python?

A way to create new classes based on existing classes:

class Animal:
    def __init__(self, name):
        self.name = name
    
    def speak(self):
        pass

class Dog(Animal):
    def speak(self):
        return f"{self.name} says Woof!"

class Cat(Animal):
    def speak(self):
        return f"{self.name} says Meow!"
                        

Q84: What are the types of inheritance?

Single inheritance: One parent class
Multiple inheritance: Multiple parent classes
Multilevel inheritance: Chain of inheritance
Hierarchical inheritance: Multiple child classes from one parent

Q85: What is method overriding?

Redefining a parent class method in a child class:

class Parent:
    def greet(self):
        return "Hello from Parent"

class Child(Parent):
    def greet(self):  # Override parent method
        return "Hello from Child"
                        

Q86: What is encapsulation?

Restricting access to methods and variables using private attributes:

class BankAccount:
    def __init__(self, balance):
        self.__balance = balance  # Private attribute
    
    def get_balance(self):
        return self.__balance
    
    def deposit(self, amount):
        self.__balance += amount
                        

Q87: What are class variables vs instance variables?

class Student:
    school = "ABC School"  # Class variable
    
    def __init__(self, name):
        self.name = name  # Instance variable
                        

Q88: What are static methods and class methods?

class Math:
    @staticmethod
    def add(x, y):
        return x + y
    
    @classmethod
    def create_default(cls):
        return cls(0, 0)
                        

Q89: What is polymorphism?

Same interface for different data types:

def make_sound(animal):
    return animal.speak()  # Works for any animal with speak() method
                        

Q90: What is the super() function?

Calls methods from parent class:

class Child(Parent):
    def __init__(self, name, age):
        super().__init__(name)  # Call parent constructor
        self.age = age
                        

🌐 Section 12: Django Web Framework (Questions 91-100)

Q91: What is Django?

Django is a high-level Python web framework that enables rapid development of secure and maintainable websites. It follows the Model-View-Template (MVT) pattern.

Q92: What are the key features of Django?

Fast development: Built-in features for common tasks
Security features built-in: Protection against common threats
Scalable: Handles high traffic applications
Versatile: Can build any type of website
ORM: Object-Relational Mapping
Admin interface: Automatic admin panel
URL routing: Clean URL design
Template engine: Powerful templating system

Q93: What is the Django MTV pattern?

Model: Data layer (database interactions)
View: Logic layer (processes requests)
Template: Presentation layer (HTML with Django template language)

Q94: How do you create a Django project and app?

# Create project
django-admin startproject myproject

# Create app
python manage.py startapp myapp
                        

Q95: What is Django ORM?

Object-Relational Mapping that allows you to interact with databases using Python objects instead of SQL:

class Book(models.Model):
    title = models.CharField(max_length=200)
    author = models.CharField(max_length=100)
    published_date = models.DateField()

# Create a book
book = Book.objects.create(title="Django Guide", author="John Doe")
                        

Q96: What are Django models?

Python classes that define the structure of database tables:

from django.db import models

class User(models.Model):
    username = models.CharField(max_length=50)
    email = models.EmailField()
    created_at = models.DateTimeField(auto_now_add=True)
                        

Q97: How do Django views work?

Functions or classes that receive HTTP requests and return HTTP responses:

from django.http import HttpResponse
from django.shortcuts import render

def home(request):
    return HttpResponse("Hello, Django!")

def about(request):
    return render(request, 'about.html', {'title': 'About Us'})
                        

Q98: What is URL routing in Django?

Mapping URLs to view functions:

# urls.py
from django.urls import path
from . import views

urlpatterns = [
    path('', views.home, name='home'),
    path('about/', views.about, name='about'),
    path('user/<int:user_id>/', views.user_detail, name='user_detail'),
]
                        

Q99: What are Django templates?

HTML files with Django template language for dynamic content:

<!DOCTYPE html>
<html>
<head>
    <title>{{ title }}</title>
</head>
<body>
    <h1>Welcome {{ user.username }}!</h1>
    {% for item in items %}
        <p>{{ item.name }}</p>
    {% endfor %}
</body>
</html>
                        

Q100: How do you handle forms in Django?

# forms.py
from django import forms

class ContactForm(forms.Form):
    name = forms.CharField(max_length=100)
    email = forms.EmailField()
    message = forms.CharField(widget=forms.Textarea)

# views.py
def contact(request):
    if request.method == 'POST':
        form = ContactForm(request.POST)
        if form.is_valid():
            # Process form data
            name = form.cleaned_data['name']
            # ... handle form submission
    else:
        form = ContactForm()
    
    return render(request, 'contact.html', {'form': form})
                        

💡 Tips for Interview Success:

Practice coding examples by hand - Write code without an IDE
Understand concepts, don't just memorize - Know the 'why' behind each concept
Be prepared to explain your reasoning - Think out loud during coding
Practice solving problems step by step - Break down complex problems
Review Django concepts thoroughly - If applying for web development roles
Know time and space complexity - Understand Big O notation
Practice debugging - Be comfortable finding and fixing errors
Stay updated with Python versions - Know the latest features

📝 Conclusion

This comprehensive set of 100 questions covers all major Python topics, including:

Python basics and syntax
Data types and variables
Control structures and functions
Object-oriented programming
File handling
Web development with Django

These questions are designed to test both theoretical knowledge and practical coding skills, making them perfect for Python developer interviews at various levels.

🎯 Ready for Your Python Interview!

This comprehensive guide covers 100 essential Python questions across all major topics. Practice regularly, understand the concepts deeply, and you'll be well-prepared for success!

Good luck with your interviews! 🐍✨

🐍 Python Interview Preparation

Key Features:

💡 Tips for Interview Success:

📝 Conclusion

🎯 Ready for Your Python Interview!