Hackerrank Object-Oriented Programming Basics 3

Question 1

How do you define a class method (not an instance method) in Python?

Accepted Answer

Use @classmethod decorator with 'cls' as first parameter

Answer

@classmethod receives the class as the first argument (conventionally named 'cls') and can access or modify class state.

Question 2

What is method overriding in Python?

Accepted Answer

A child class provides its own implementation of a method inherited from the parent

Answer

Method overriding lets a subclass redefine an inherited method, replacing the parent's behavior with its own.

Question 3

What is the output of:
class A:
    x = 10
a1 = A()
A.x = 20
print(a1.x)

Accepted Answer

20

Answer

a1.x resolves to the class attribute A.x because no instance attribute 'x' was set on a1; after A.x = 20, it reads 20.

Question 4

Which statement about Python's __str__ method is correct?

Accepted Answer

It is called by str() and print() to get a human-readable string

Answer

__str__ should return a user-friendly string; Python calls it automatically when you use str(obj) or print(obj).

Question 5

What does super() do in a subclass?

Accepted Answer

Returns a proxy that delegates method calls to the parent class

Answer

super() returns a proxy object that forwards method calls to the next class in the MRO, typically the parent class.

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