MCQs on Object-Oriented Programming in Ruby | Ruby
Explore core Object-Oriented Programming (OOP) concepts in Ruby, from classes and objects to inheritance and polymorphism. Learn how to structure your Ruby applications with these essential OOP principles.
MCQs on Object-Oriented Programming in Ruby
Section 1: Introduction to OOP Concepts (6 Questions)
- What is the core principle of Object-Oriented Programming (OOP)?
- a) Data is isolated in functions
- b) Data is organized around objects and classes
- c) Data is processed in a sequence
- d) Functions operate on global data
- Which of the following is not an OOP principle?
- a) Encapsulation
- b) Inheritance
- c) Polymorphism
- d) Compilation
- In OOP, what does encapsulation refer to?
- a) Using classes to organize data
- b) Hiding data within objects and restricting access
- c) Allowing classes to inherit from other classes
- d) Defining multiple methods for the same functionality
- What is the primary purpose of inheritance in OOP?
- a) To avoid code repetition by reusing properties and methods
- b) To hide data within a class
- c) To define new data types
- d) To define an interface for classes
- Which of the following OOP concepts is implemented through the use of polymorphism?
- a) Different methods having the same name but different implementations
- b) Classes inheriting properties from parent classes
- c) Restricting access to object properties
- d) Wrapping data and functions into a single unit
- In Ruby, which keyword is used to define a class?
- a)
object - b)
def - c)
class - d)
module
- a)
Section 2: Classes and Objects (6 Questions)
- In Ruby, how do you instantiate an object of a class?
- a)
new ClassName() - b)
ClassName.new - c)
object.new ClassName() - d)
new ClassName
- a)
- What is the primary purpose of a constructor in a Ruby class?
- a) To define the properties of a class
- b) To initialize objects of a class
- c) To invoke methods of the class
- d) To change the class variables
- In Ruby, what method is used to initialize an object of a class?
- a)
initialize() - b)
new() - c)
start() - d)
create()
- a)
- Which of the following is a valid way to access an object’s instance variable in Ruby?
- a)
object.variable_name - b)
object.get_variable_name - c)
object.variable_name() - d)
object.@variable_name
- a)
- What happens if you call a method on an object that is not defined in its class?
- a) Ruby will search for it in the parent class
- b) Ruby will throw an error immediately
- c) Ruby will return
nil - d) Ruby will attempt to create the method dynamically
- Which of the following is used to access the class of an object in Ruby?
- a)
object.class - b)
class(object) - c)
object.instance_of? - d)
object.define_class
- a)
Section 3: Instance Variables and Methods (6 Questions)
- What is an instance variable in Ruby?
- a) A variable shared by all objects of a class
- b) A variable that stores methods within an object
- c) A variable whose value is accessible by all classes
- d) A variable that is unique to each object of a class
- How are instance variables defined in Ruby?
- a) By using
@before the variable name - b) By using
$before the variable name - c) By using
@before the method name - d) By using
@@before the variable name
- a) By using
- Which of the following correctly defines an instance method in Ruby?
- a)
def method_name - b)
method method_name - c)
def method_name() - d)
function method_name()
- a)
- In Ruby, an instance variable’s value can be accessed or modified using which method?
- a) Getter and setter methods
- b) Direct access within the class
- c) Only getter methods
- d) Public methods
- What will happen if you attempt to access an uninitialized instance variable in Ruby?
- a) It will throw an error
- b) It will return
nil - c) It will initialize the variable automatically
- d) It will cause an infinite loop
- How do you define a getter method for an instance variable in Ruby?
- a)
def variable_name - b)
def get_variable_name - c)
def variable_name() - d)
def variable_name; end
- a)
Section 4: Class Variables and Methods (6 Questions)
- In Ruby, how do you define a class variable?
- a) By using
@before the variable name - b) By using
@@before the variable name - c) By using
$before the variable name - d) By using
class_variablesyntax
- a) By using
- What is the scope of a class variable in Ruby?
- a) It is accessible only inside the class
- b) It is accessible across all instances of the class and subclasses
- c) It is accessible only inside one object
- d) It can only be accessed from outside the class
- What keyword is used to define a class method in Ruby?
- a)
class_method - b)
def - c)
self - d)
static
- a)
- What will be the output of the following Ruby code?rubyCopy code
class MyClass @@class_variable = 5 def self.print_class_variable puts @@class_variable end end MyClass.print_class_variable- a)
nil - b)
5 - c)
MyClass - d)
Error
- a)
- Which of the following is the correct way to define a class method in Ruby?
- a)
def MyClass.method_name - b)
def self.method_name - c)
def method_name(self) - d)
def method_name::self
- a)
- How can you access a class variable from an instance method in Ruby?
- a) By using
@@variable_name - b) By using
@variable_name - c) By using
variable_name - d) By using
self.variable_name
- a) By using
Section 5: Inheritance and Polymorphism (6 Questions)
- What does inheritance allow a class to do in Ruby?
- a) It allows a class to inherit methods from another class
- b) It defines the structure of a class
- c) It adds data attributes to a class
- d) It allows classes to merge with each other
- How do you define a subclass in Ruby?
- a)
class SubClass < SuperClass - b)
class SubClass() inherits SuperClass - c)
class SubClass from SuperClass - d)
class SubClass: SuperClass
- a)
- Which Ruby keyword is used to refer to the parent class?
- a)
super - b)
parent - c)
class - d)
self
- a)
- In Ruby, what does polymorphism allow a method to do?
- a) It allows a method to be invoked with different arguments
- b) It allows a method to act differently based on the object’s class
- c) It allows multiple methods with the same name
- d) It allows a class to inherit methods from other classes
- How would you call the superclass method inside a subclass method in Ruby?
- a)
super() - b)
parent() - c)
call_super() - d)
super_method()
- a)
- Which of the following is an example of polymorphism in Ruby?
- a) A method that behaves differently based on the class of the object
- b) A class inheriting from another class
- c) A method that accepts multiple arguments
- d) A class that has only one method
Answer Key
| Qno | Answer |
|---|---|
| 1 | b) Data is organized around objects and classes |
| 2 | d) Compilation |
| 3 | b) Hiding data within objects and restricting access |
| 4 | a) To avoid code repetition by reusing properties and methods |
| 5 | a) Different methods having the same name but different implementations |
| 6 | c) class |
| 7 | b) ClassName.new |
| 8 | b) To initialize objects of a class |
| 9 | a) initialize() |
| 10 | a) object.variable_name |
| 11 | a) Ruby will search for it in the parent class |
| 12 | a) object.class |
| 13 | d) A variable that is unique to each object of a class |
| 14 | a) By using @ before the variable name |
| 15 | b) It will return nil |
| 16 | a) Getter and setter methods |
| 17 | b) It will return nil |
| 18 | a) def variable_name |
| 19 | b) By using @@ before the variable name |
| 20 | b) It is accessible across all instances of the class and subclasses |
| 21 | c) self |
| 22 | b) 5 |
| 23 | b) def self.method_name |
| 24 | a) By using @@variable_name |
| 25 | a) It allows a class to inherit methods from another class |
| 26 | a) class SubClass < SuperClass |
| 27 | a) super |
| 28 | b) It allows a method to act differently based on the object’s class |
| 29 | a) super() |
| 30 | a) A method that behaves differently based on the class of the object |