Welcome to MCQ (Multiple Choice Questions) on Object-Oriented Programming (OOP) in Python! Whether you are a newcomer taking your first steps in Python or someone looking to brush up your OOP concepts, this set of 20 Multiple Choice Questions (MCQs) will serve as a great learning resource.
OOP is one of the foundational paradigms in programming and is extensively used in Python to organize code into reusable structures. It not only enhances code readability but also makes it easier to manage and maintain. Understanding the basic concepts like classes, objects, inheritance, and polymorphism is critical for any Python programmer.
This MCQ covers key aspects of OOP in Python, ranging from defining classes and creating objects to more advanced topics like method overriding and encapsulation. Each question comes with a detailed explanation to help you grasp the underlying principles. So, are you ready to test your understanding of OOP in Python? Let's dive in!
1. Which of the following is not a key concept in OOP?
a) Inheritance
b) Polymorphism
c) Multiprocessing
d) Encapsulation
Answer:
c) Multiprocessing
Explanation:
While inheritance, polymorphism, and encapsulation are core OOP concepts, multiprocessing pertains to concurrent execution and isn't specific to OOP.
2. In Python, an object is:
a) A real-world entity
b) A collection of data and methods
c) Always physical
d) Only data
Answer:
b) A collection of data and methods
Explanation:
In OOP, an object is an encapsulation of data (attributes) and methods (functions) that operate on the data.
3. Which of the following is correct about class attributes?
a) They are always public
b) They cannot be changed outside the class
c) They are shared across all instances of a class
d) They can't be initialized in a constructor
Answer:
c) They are shared across all instances of a class
Explanation:
Class attributes, unlike instance attributes, are shared across all instances of the class.
4. What is the purpose of a constructor in a class?
a) To construct the methods of the class
b) To initialize an object's attributes when it's created
c) To destroy an instance
d) To make a class abstract
Answer:
b) To initialize an object's attributes when it's created
Explanation:
Constructors are special methods that get invoked when an object is instantiated, primarily used to initialize attributes.
5. In Python, how is the constructor defined for a class?
a) init()
b) construct()
c) __init__()
d) __construct__()
Answer:
c) __init__()
Explanation:
In Python, the constructor method is named __init__().
6. What is the concept of inheriting properties of one class into another class?
a) Polymorphism
b) Multiprocessing
c) Encapsulation
d) Inheritance
Answer:
d) Inheritance
Explanation:
Inheritance allows one class (child/subclass) to inherit attributes and methods from another class (parent/superclass).
7. Which of the following keywords is used to create a subclass in Python?
a) extend
b) inherits
c) class
d) subclass
Answer:
c) class
Explanation:
The class keyword is used, but the inheritance relationship is determined by the parentheses. For example: class SubClass(ParentClass):.
8. What does method overriding mean in Python?
a) Altering a method by changing its parameters in the same class.
b) Modifying the behavior of an inherited method in the subclass.
c) Using the same method name in multiple classes.
d) Making a method static.
Answer:
b) Modifying the behavior of an inherited method in the subclass.
Explanation:
Method overriding involves defining in the subclass a method with the same name as in the superclass, thus altering its behavior in the derived class.
9. How does Python support method overloading?
a) By creating multiple methods with the same name but different parameters.
b) By creating static methods.
c) Through default arguments and variable-length argument lists.
d) Python doesn’t support method overloading.
Answer:
c) Through default arguments and variable-length argument lists.
Explanation:
Unlike some other languages where method overloading is achieved by having multiple methods with the same name but different parameters, Python achieves this using default arguments and variable-length argument lists (using *args and **kwargs).
10. In method overriding, if the subclass has the same method as declared in the parent class, which version of the method will be executed?
a) Parent class
b) Subclass
c) Both
d) Neither
Answer:
b) Subclass
Explanation:
If a method is overridden in the subclass, the version of the method defined in the subclass will be executed, not the one in the parent class.
11. What's the primary use of the super() function in Python OOP?
a) To call a superclass's constructor
b) To call a method from another module
c) To override a method
d) To create an instance of a class
Answer:
a) To call a superclass's constructor
Explanation:
super() allows us to call a method from the parent class, commonly used in the constructor (__init__) of a subclass to initialize attributes from the superclass.
12. Which of the following is a special method in Python?
a) method()
b) __method__
c) _method_
d) method_()
Answer:
b) __method__
Explanation:
In Python, methods wrapped with double underscores (e.g., __init__) are special methods, often called "magic" or "dunder" methods.
13. How do you declare a private attribute in a class?
a) private attr
b) _attr
c) __attr
d) private_attr
Answer:
c) __attr
Explanation:
In Python, attributes prefixed with double underscores are considered private and can't be accessed directly outside the class (though there are ways around this due to Python's nature of name mangling).
14. What is the concept of using one operation to work with different types of objects?
a) Encapsulation
b) Inheritance
c) Polymorphism
d) Abstraction
Answer:
c) Polymorphism
Explanation:
Polymorphism, from Greek words meaning "many shapes", allows one interface to be used for a general class of actions, irrespective of the types of objects.
15. Which of the following can be used to restrict access to members of a class?
a) Public
b) Open
c) Protected
d) Unrestricted
Answer:
c) Protected
Explanation:
Prefixing an attribute with a single underscore (e.g., _attr) conventionally indicates it is protected and shouldn't be accessed outside the class, though it still can be. It's more of a convention than an enforced restriction.
16. Which method gets called when an object is deleted?
a) __del__
b) __delete__
c) __remove__
d) __exit__
Answer:
a) __del__
Explanation:
The __del__ method is a destructor and gets called when an object is deleted.
17. What does the isinstance() function do?
a) Checks if a variable is of a specific type
b) Checks if an object is an instance of a particular class or tuple of classes
c) Checks if two class instances are the same
d) Instantiates an object
Answer:
b) Checks if an object is an instance of a particular class or tuple of classes
Explanation:
The isinstance() function returns True if the object is an instance of the class or a tuple of classes.
18. Which of the following is not a type of class method?
a) Static method
b) Instance method
c) Modular method
d) Class method
Answer:
c) Modular method
Explanation:
Python classes have instance methods, static methods, and class methods. There's no "modular method."
19. What is the primary difference between a class method and a static method?
a) Class methods cannot modify the class state, while static methods can.
b) Static methods cannot modify the class state, while class methods can.
c) Class methods can access and modify class-level attributes while static methods can't.
d) There's no difference; they are the same.
Answer:
c) Class methods can access and modify class-level attributes while static methods can't.
Explanation:
A class method takes a reference to the class (typically cls) as its first parameter, allowing it to access and modify class-level attributes. In contrast, static methods don't have access to class or instance-specific data and behave like plain functions.
20. In a class definition, what does a property decorator (@property) do?
a) Makes a method accessible like an attribute
b) Makes an attribute private
c) Declares a static method
d) Declares a constructor
Answer:
a) Makes a method accessible like an attribute
Explanation:
The @property decorator allows us to define methods in a class that are accessible like attributes without needing to invoke them like functions.
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