Classes and objects in Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a class named Car.

Python

class [1]:
    pass

Drag options to blanks, or click blank then click option'

ACar

Bcar

Cvehicle

DCarClass

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase names for the class.

Using a different class name than asked.

The class name should be Car to match the problem statement.

2fill in blank

medium

Complete the code to create an object named my_car from the Car class.

Python

my_car = [1]()

Drag options to blanks, or click blank then click option'

ACar

Bcar

CVehicle

Dcar()

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase 'car' instead of 'Car'.

Adding extra parentheses like 'car()()'.

To create an object, use the class name Car followed by parentheses.

3fill in blank

hard

Fix the error in the method definition to correctly initialize the Car object with a model name.

Python

class Car:
    def __init__([1], model):
        [2].model = model

Drag options to blanks, or click blank then click option'

Aself

Bcls

Cthis

Dself, self

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'cls' which is for class methods.

Using 'this' which is not Python syntax.

Repeating 'self' in the parameter list.

The first parameter of methods in a class should be self, which refers to the object itself.

4fill in blank

hard

Fill both blanks to add a method named display_model that prints the car's model.

Python

class Car:
    def __init__(self, model):
        self.model = model
    def [1](self):
        print(self.[2])

Drag options to blanks, or click blank then click option'

Adisplay_model

Bshow_model

Cmodel

Dmodel_name

Attempts:

3 left

💡 Hint

Common Mistakes

Using a method name that doesn't match the instruction.

Printing an attribute name that does not exist.

The method should be named display_model and print the attribute model.

5fill in blank

hard

Fill all three blanks to create a Car object with model 'Tesla' and call its display_model method.

Python

my_car = [1]([2])
my_car.[3]()

Drag options to blanks, or click blank then click option'

ACar

B'Tesla'

Cdisplay_model

Dcar

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase 'car' instead of 'Car'.

Forgetting quotes around the model name.

Calling a method name that does not exist.

Create the object with Car, pass the model name as a string 'Tesla', and call the method display_model.

Practice

1. What is the main purpose of a class in Python?

easy

A. To execute code immediately

B. To store data in variables only

C. To create a blueprint for objects

D. To perform mathematical calculations

Solution

1. Step 1: Understand what a class represents

   A class is like a blueprint or template that defines how objects are created and what they can do.

2. Step 2: Identify the role of a class

   Classes organize code by grouping data and functions that belong together, allowing creation of many objects from the same blueprint.

3. Final Answer:

   To create a blueprint for objects -> Option C

4. Quick Check:

   Class = blueprint for objects [OK]

Hint: Classes define blueprints; objects are instances [OK]

Common Mistakes:

• Thinking classes run code immediately
• Confusing classes with simple variables
• Believing classes only store data

2. Which of the following is the correct way to define a class named Car in Python?

easy

A. class Car():

B. def Car():

C. function Car():

D. Car class:

Solution

1. Step 1: Recall Python class syntax

   In Python, classes are defined using the keyword class followed by the class name and parentheses.

2. Step 2: Check each option

   class Car(): uses class Car(): which is correct syntax. Others use wrong keywords or formats.

3. Final Answer:

   class Car(): -> Option A

4. Quick Check:

   Class definition starts with 'class' keyword [OK]

Hint: Use 'class ClassName():' to define a class [OK]

Common Mistakes:

• Using 'def' instead of 'class'
• Using 'function' keyword (not Python)
• Missing 'class' keyword

3. What will be the output of this code?

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

my_dog = Dog("Buddy")
print(my_dog.bark())

medium

A. Error: missing self parameter

B. Buddy says Woof!

C. Dog says Woof!

D. Woof!

Solution

1. Step 1: Understand the __init__ method

   The __init__ method sets the name attribute to "Buddy" when my_dog is created.

2. Step 2: Analyze the bark method call

   The bark method returns a string using the dog's name, so it returns "Buddy says Woof!".

3. Final Answer:

   Buddy says Woof! -> Option B

4. Quick Check:

   Method uses self.name = Buddy [OK]

Hint: Methods use self to access object data [OK]

Common Mistakes:

• Forgetting to pass 'self' in methods
• Confusing class name with object name
• Expecting method to print instead of return

4. Find the error in this class definition:

class Person():
    def __init__(self, name):
        name = name

p = Person("Alice")
print(p.name)

medium

A. Class name should be lowercase

B. Missing self in __init__ parameters

C. print(p.name) should be print(name)

D. Should assign to self.name, not name

Solution

1. Step 1: Check attribute assignment in __init__

   The code assigns name = name, which only changes the local variable, not the object's attribute.

2. Step 2: Correct assignment to object attribute

   It should be self.name = name to store the value in the object for later access.

3. Final Answer:

   Should assign to self.name, not name -> Option D

4. Quick Check:

   Use self.attribute = value to save data [OK]

Hint: Assign attributes with self.attribute = value [OK]

Common Mistakes:

• Assigning to local variable instead of self.attribute
• Forgetting self in method parameters
• Trying to print undefined variables

5. You want to create a class BankAccount that stores an account holder's name and balance. It should have a method deposit(amount) that adds money to the balance only if the amount is positive. Which code correctly implements this?

hard

A. class BankAccount():
def __init__(self, name, balance=0):
self.name = name
self.balance = balance
def deposit(self, amount):
if amount > 0:
self.balance += amount

B. class BankAccount():
def __init__(self, name):
self.name = name
balance = 0
def deposit(self, amount):
self.balance = self.balance + amount

C. class BankAccount():
def __init__(self, name, balance=0):
self.name = name
self.balance = balance
def deposit(self, amount):
self.balance += amount

D. class BankAccount():
def __init__(self, name):
self.name = name
self.balance = 0
def deposit(self, amount):
if amount >= 0:
self.balance = amount

Solution

1. Step 1: Check __init__ method for attributes

   class BankAccount(): def __init__(self, name, balance=0): self.name = name self.balance = balance def deposit(self, amount): if amount > 0: self.balance += amount correctly sets self.name and self.balance with a default balance of 0.

2. Step 2: Verify deposit method logic

   class BankAccount(): def __init__(self, name, balance=0): self.name = name self.balance = balance def deposit(self, amount): if amount > 0: self.balance += amount adds amount to self.balance only if amount > 0, which matches the requirement.

3. Final Answer:

   Correctly implements the class with proper attribute initialization and deposit validation -> Option A

4. Quick Check:

   Check attribute setup and positive amount condition [OK]

Hint: Check attribute setup and validate input in methods [OK]

Common Mistakes:

• Not using self.balance to store balance
• Adding amount without checking if positive
• Overwriting balance instead of adding
• Missing default balance initialization