Creating objects in Python - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

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

Python

class Car:
    def __init__(self, brand):
        self.brand = brand

my_car = [1]

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

ACar('Toyota')

BCar = 'Toyota'

CCar.brand('Toyota')

DCar('Toyota')()

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to call a method on the class instead of creating an object.

Assigning a string directly to the class name.

Adding extra parentheses after object creation.

To create an object, call the class name with parentheses and pass required arguments. Here, Car('Toyota') creates an object with brand 'Toyota'.

2fill in blank

medium

Complete the code to access the color attribute of the car object.

Python

class Car:
    def __init__(self, color):
        self.color = color

car = Car('red')
print(car.[1])

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

Abrand

Bcolor

CColor

Dpaint

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different attribute name than defined.

Capitalizing the attribute name incorrectly.

Trying to access an attribute that does not exist.

To access an attribute, use the object name followed by a dot and the attribute name exactly as defined. Here, car.color gives 'red'.

3fill in blank

hard

Fix the error in the code to correctly create an object of class Person.

Python

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

person = Person[1]

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

A['Alice']

B('Alice',)

C('Alice')

D('Alice')()

Attempts:

3 left

💡 Hint

Common Mistakes

Using square brackets instead of parentheses.

Adding extra parentheses after the argument list.

Passing a tuple with a comma when not needed.

To create an object, call the class with parentheses and pass arguments. Person('Alice') is correct. Using square brackets or extra parentheses causes errors.

4fill in blank

hard

Fill both blanks to create a dictionary with keys as names and values as ages from the people list.

Python

people = [('Alice', 30), ('Bob', 25), ('Cara', 27)]
ages = {person[1]: person[2] for person in people}

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

A[0]

B[1]

C:

D=>

Attempts:

3 left

💡 Hint

Common Mistakes

Using '=>' instead of ':' in dictionary comprehension.

Mixing up indices for name and age.

Using parentheses instead of square brackets for tuple access.

To create a dictionary comprehension, use {key: value for item in list}. Here, person[0] is the name (key) and person[1] is the age (value), separated by a colon. The full comprehension is {person[0]: person[1] for person in people}.

5fill in blank

hard

Fill all three blanks to create a list of Person objects from the names list.

Python

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

names = ['Anna', 'Ben', 'Cara']
people = [[1]([2]) for [3] in names]

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

APerson

Bname

Cn

DPerson()

Attempts:

3 left

💡 Hint

Common Mistakes

Calling Person() without arguments.

Using a different variable name inside the call than in the loop.

Adding parentheses after the class name in the options.

To create objects in a list comprehension, call the class with the loop variable. Here, Person(n) for n in names creates objects for each name.

Practice

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

easy

A. To define a new class method

B. To delete the object from memory

C. To initialize the object's attributes when it is created

D. To print the object details

Solution

1. Step 1: Understand the role of __init__

   The __init__ method is called automatically when a new object is created from a class.

2. Step 2: Identify what __init__ does

   It sets up the initial state by assigning values to the object's attributes.

3. Final Answer:

   To initialize the object's attributes when it is created -> Option C

4. Quick Check:

   __init__ initializes object attributes [OK]

Hint: Remember: __init__ sets up new objects [OK]

Common Mistakes:

• Thinking __init__ deletes objects
• Confusing __init__ with printing methods
• Believing __init__ defines new classes

2. Which of the following is the correct way to create an object of class Car in Python?

easy

A. car = new Car()

B. car = Car()

C. car = Car.create()

D. car = Car[]

Solution

1. Step 1: Recall Python object creation syntax

   In Python, you create an object by calling the class name followed by parentheses.

2. Step 2: Eliminate invalid syntaxes

   new Car() is Java/C++ style, invalid in Python. Car.create() assumes a non-existent method. Car[] is invalid. Only Car() works.

3. Final Answer:

   car = Car() -> Option B

4. Quick Check:

   Use ClassName() to create objects [OK]

Hint: Use ClassName() to create objects in Python [OK]

Common Mistakes:

• Using 'new' keyword like other languages
• Trying to call a non-existent create() method
• Using square brackets instead of parentheses

3. What will be the output of this code?

class Dog:
    def __init__(self, name):
        self.name = name

d = Dog('Buddy')
print(d.name)

medium

A. Buddy

B. Dog

C. name

D. Error

Solution

1. Step 1: Understand object creation and attribute assignment

   The Dog class has an __init__ method that sets self.name to the given argument.

2. Step 2: Trace the code execution

   When d = Dog('Buddy') runs, d.name becomes 'Buddy'. Printing d.name outputs 'Buddy'.

3. Final Answer:

   Buddy -> Option A

4. Quick Check:

   Object attribute prints assigned value [OK]

Hint: Print object.attribute to see stored value [OK]

Common Mistakes:

• Printing class name instead of attribute
• Expecting 'name' string output
• Confusing attribute with variable name

4. Identify the error in this code:

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

p = Person(30)
print(p.age)

medium

A. Attribute not assigned to self

B. Syntax error in class definition

C. Missing self in method parameters

D. print statement is incorrect

Solution

1. Step 1: Check attribute assignment inside __init__

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

2. Step 2: Correct way to assign attribute

   It should be self.age = age to store the value in the object.

3. Final Answer:

   Attribute not assigned to self -> Option A

4. Quick Check:

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

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

Common Mistakes:

• Forgetting to use self for attributes
• Confusing local variables with object attributes
• Assuming assignment without self works

5. You want to create a class Book that stores title and author. Which code correctly creates an object and prints the title and author?

hard

A. class Book:
def __init__(self):
self.title = '1984'
self.author = 'Orwell'

b = Book('1984', 'Orwell')
print(b.title, b.author)

B. class Book:
def __init__(self, title, author):
title = title
author = author

b = Book('1984', 'Orwell')
print(b.title, b.author)

C. class Book:
def __init__(self, title, author):
self.title = title

b = Book('1984', 'Orwell')
print(b.title, b.author)

D. class Book:
def __init__(self, title, author):
self.title = title
self.author = author

b = Book('1984', 'Orwell')
print(b.title, b.author)

Solution

1. Step 1: Check attribute assignment in constructor

   The correct code defines __init__ with title and author parameters and assigns self.title = title and self.author = author.

2. Step 2: Verify object creation and printing

   The object is created by passing arguments Book('1984', 'Orwell') matching the parameters, and both attributes print correctly. Others fail on missing self, incomplete assignments, or parameter mismatch.

3. Final Answer:

   Correctly assigns both attributes to self using parameters -> Option D

4. Quick Check:

   Assign all attributes with self and pass parameters [OK]

Hint: Assign all attributes with self and pass parameters [OK]

Common Mistakes:

• Not assigning attributes to self
• Missing parameters in constructor
• Providing arguments to a parameterless constructor