Hackerrank - HackerRank Python Object-Oriented Programming Basics Questions and Answers

Question 1

Which of the following best describes the relationship between a class and an object in Python?

Accepted Answer

An object is a specific, concrete realization of a class.

Answer

A class acts as a blueprint or template that defines the properties (attributes) and behaviors (methods) for a certain type of entity. An object is a specific instance created from that class, with its own unique state.

Question 2

In a Python class, what is the primary role of the special method `__init__`?

Accepted Answer

To initialize the state of a newly created object with its starting attributes.

Answer

The `__init__` method is a special method, often called a constructor or initializer, that Python calls automatically when a new instance of a class is created. Its primary purpose is to set up the initial state of the object by assigning values to its instance attributes.

Question 3

Analyze the following code. What principle of object-oriented programming does the `Penguin` class's `fly` method demonstrate?

Accepted Answer

Method Overriding

Answer

Method overriding occurs when a subclass (child class) provides a specific implementation for a method that is already defined in its superclass (parent class). Here, the `Penguin` class overrides the `fly` method inherited from the `Bird` class to provide its own specialized behavior.

Question 4

A developer wants to prevent accidental modification of a `_balance` attribute from outside the `Account` class. According to Python's conventions for encapsulation, which naming prefix should be used for the attribute?

Accepted Answer

__balance

Answer

Using a double underscore prefix (e.g., `__balance`) invokes Python's name mangling feature. This renames the attribute internally to `_ClassName__attributeName`, making it difficult to access directly from outside the class and thus preventing accidental modification in subclasses. This is Python's mechanism for creating 'private' attributes.

Question 5

What will be the output of the following Python code snippet?

Accepted Answer

Canis familiaris, Canis familiaris

Answer

The line `dog1.species = "Canis lupus"` creates a new *instance attribute* for `dog1` that shadows the class attribute. It does not change the `species` attribute of the `Dog` class itself. Therefore, `Dog.species` remains "Canis familiaris", and `dog2.species` also refers to the original class attribute.

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Hackerrank - HackerRank Python Object-Oriented Programming Basics Questions and Answers