Solution on Class and Object
🧩 1. Define a Basic Class
Problem:
Create a class Car with attributes brand, model, and year.
Include a method start_engine() that prints a message like:
"The 2022 Tesla Model S engine has started."
Explanation:
A simple intro to defining a class, initializing attributes, and using them in a method.
Solution:
class Car:
def __init__(self, brand, model, year):
self.brand = brand
self.model = model
self.year = year
def start_engine(self):
print(f"The {self.year} {self.brand} {self.model} engine has started.")
car1 = Car("Tesla", "Model S", 2022)
car1.start_engine()
🧩 2. Class Representing a Movie
Problem:
Create a class Movie with attributes title, director, and rating.
Add a method describe() that prints all details in one line.
Then create two movie objects and display their information.
Explanation:
Practices constructors, instance variables, and string formatting.
Solution:
class Movie:
def __init__(self, title, director, rating):
self.title = title
self.director = director
self.rating = rating
def describe(self):
print(f"🎬 {self.title} directed by {self.director} — Rating: {self.rating}/10")
m1 = Movie("Inception", "Christopher Nolan", 9)
m2 = Movie("Interstellar", "Christopher Nolan", 8.5)
m1.describe()
m2.describe()
🧩 3. Shopping Cart with Total Calculation
Problem:
Create a class ShoppingCart that keeps a list of items and their prices.
Add methods:
add_item(name, price)→ adds an item to carttotal()→ returns total price of all items
Explanation:
Introduces data storage in objects (using lists).
Solution:
class ShoppingCart:
def __init__(self):
self.items = []
def add_item(self, name, price):
self.items.append((name, price))
def total(self):
total_price = sum(price for _, price in self.items)
return total_price
cart = ShoppingCart()
cart.add_item("Laptop", 800)
cart.add_item("Mouse", 20)
print("Total Bill:", cart.total())
🧩 4. Track Employee Bonuses
Problem:
Create a class Employee with name and salary.
Add a method apply_bonus(percent) that increases salary by the given percentage.
Show the old and new salary.
Explanation:
Covers arithmetic operations inside methods and modifying attributes.
Solution:
class Employee:
def __init__(self, name, salary):
self.name = name
self.salary = salary
def apply_bonus(self, percent):
new_salary = self.salary + (self.salary * percent / 100)
print(f"{self.name}'s new salary after {percent}% bonus: {new_salary}")
emp = Employee("Riya", 50000)
emp.apply_bonus(10)
🧩 5. Temperature Converter
Problem:
Create a class Temperature with a Celsius value.
Add methods:
to_fahrenheit()— returns Fahrenheitto_kelvin()— returns Kelvin
Explanation:
Good for practicing methods that return computed results.
Solution:
class Temperature:
def __init__(self, celsius):
self.celsius = celsius
def to_fahrenheit(self):
return (self.celsius * 9/5) + 32
def to_kelvin(self):
return self.celsius + 273.15
temp = Temperature(25)
print("Fahrenheit:", temp.to_fahrenheit())
print("Kelvin:", temp.to_kelvin())
🧩 6. Simple Library System
Problem:
Create a class Book with attributes title, author, and is_available (default True).
Add methods:
borrow()→ marks the book unavailablereturn_book()→ marks it available again
Explanation:
Demonstrates modifying internal state with boolean flags.
Solution:
class Book:
def __init__(self, title, author):
self.title = title
self.author = author
self.is_available = True
def borrow(self):
if self.is_available:
self.is_available = False
print(f"You borrowed '{self.title}'")
else:
print(f"'{self.title}' is currently unavailable")
def return_book(self):
self.is_available = True
print(f"'{self.title}' has been returned")
book1 = Book("1984", "George Orwell")
book1.borrow()
book1.return_book()
🧩 7. Simple Bank Account with Validation
Problem:
Create a class BankAccount with holder_name and balance (default 0).
Add methods:
deposit(amount)withdraw(amount)with validation if balance is sufficientdisplay_balance()
Explanation:
Encourages conditional logic within class methods.
Solution:
class BankAccount:
def __init__(self, holder_name, balance=0):
self.holder_name = holder_name
self.balance = balance
def deposit(self, amount):
self.balance += amount
print(f"Deposited {amount}. New balance: {self.balance}")
def withdraw(self, amount):
if amount <= self.balance:
self.balance -= amount
print(f"Withdrew {amount}. Remaining balance: {self.balance}")
else:
print("Insufficient balance!")
acc = BankAccount("Amit", 1000)
acc.deposit(500)
acc.withdraw(1200)
acc.display_balance = lambda: print(f"Final Balance: {acc.balance}")
acc.display_balance()
🧩 8. Class for Student Marks
Problem:
Create a class Student that stores name and three subject marks.
Add a method average() that returns the average mark,
and another method grade() that returns:
"A"if avg ≥ 80"B"if avg ≥ 60"C"otherwise.
Explanation:
Combines logic, arithmetic, and conditional statements.
Solution:
class Student:
def __init__(self, name, m1, m2, m3):
self.name = name
self.marks = [m1, m2, m3]
def average(self):
return sum(self.marks) / 3
def grade(self):
avg = self.average()
if avg >= 80:
return "A"
elif avg >= 60:
return "B"
else:
return "C"
s1 = Student("Priya", 85, 78, 92)
print(f"{s1.name}'s Grade:", s1.grade())
🧩 9. Car Mileage Tracker
Problem:
Create a class MileageTracker for cars with attributes distance and fuel_used.
Add a method calculate_mileage() that returns mileage (distance / fuel).
Handle division by zero gracefully.
Explanation:
Mixes object attributes, math, and simple error handling.
Solution:
class MileageTracker:
def __init__(self, distance, fuel_used):
self.distance = distance
self.fuel_used = fuel_used
def calculate_mileage(self):
if self.fuel_used == 0:
return "Fuel used cannot be zero!"
return self.distance / self.fuel_used
car = MileageTracker(500, 25)
print("Mileage:", car.calculate_mileage(), "km/l")
🧩 10. Product Discount System
Problem:
Create a class Product with name, price, and category.
Add a method apply_discount(percent) that reduces price by that percent.
Add another method display_info() to print product details.
Explanation:
Tests object creation, math operation, and clean output formatting.
Solution:
class Product:
def __init__(self, name, price, category):
self.name = name
self.price = price
self.category = category
def apply_discount(self, percent):
self.price -= self.price * (percent / 100)
def display_info(self):
print(f"Product: {self.name} | Category: {self.category} | Price: ₹{self.price:.2f}")
item = Product("Headphones", 2000, "Electronics")
item.apply_discount(10)
item.display_info()