OOP MCQs

This comprehensive set of Object-Oriented Programming (OOP) MCQs is designed to cover all essential topics required for success in programming and software development exams. Focused on key OOP concepts such as classes, objects, inheritance, polymorphism, encapsulation, and abstraction, these MCQs are crafted to help students build a strong foundation in object-oriented design and programming principles.

Who should practice OOP MCQs?

Students preparing for computer science, software engineering, or IT exams that include OOP concepts.
Individuals aiming to strengthen their understanding of core OOP principles like inheritance, polymorphism, and encapsulation.
Candidates preparing for programming interviews or certification exams that assess problem-solving through object-oriented design.
Learners interested in mastering the syntax and semantics of OOP languages such as Java, C++, Python, or C#.
Developers focused on improving their coding skills, design patterns, and software development best practices.
Suitable for all learners, including those looking to enhance their knowledge and application of OOP for academic or professional success.

1. What does OOP stand for?

A) Object Oriented Programming
B) Only Object Programming
C) Oriented Object Programming
D) Organized Object Programming

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2. What is an object in OOP?

A) A data type
B) An instance of a class
C) A function
D) A method

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3. Which concept allows objects to take many forms in OOP?

A) Inheritance
B) Encapsulation
C) Polymorphism
D) Abstraction

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4. What is a class in OOP?

A) A template for creating objects
B) A function
C) A variable
D) A data type

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5. What does encapsulation in OOP mean?

A) Hiding internal state and requiring all interaction to be performed through an object’s methods
B) Inheriting properties from another class
C) Creating multiple instances of a class
D) Allowing a class to take multiple forms

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6. What is inheritance in OOP?

A) A mechanism to inherit properties and behavior from another class
B) A way to hide data
C) A technique to manage memory
D) A type of loop

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7. Which of the following is an example of polymorphism in OOP?

A) Overloading methods
B) Using for-loops
C) Declaring variables
D) Defining a class

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8. What is the term for creating a new object from a class in OOP?

A) Instantiation
B) Inheritance
C) Overloading
D) Overriding

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9. In OOP, which concept helps to hide the complexity of the system?

A) Encapsulation
B) Inheritance
C) Abstraction
D) Polymorphism

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10. Which of the following refers to the ability of a subclass to use methods and properties of a superclass?

A) Inheritance
B) Encapsulation
C) Polymorphism
D) Composition

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11. What does method overloading refer to in OOP?

A) Defining multiple methods with the same name but different parameters
B) Inheriting multiple classes
C) Hiding methods from other classes
D) Creating an object multiple times

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12. What is the main benefit of encapsulation in OOP?

A) Reducing code duplication
B) Making the code easier to understand
C) Restricting access to some of the object’s components
D) Allowing multiple forms of methods

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13. Which OOP concept is represented by the ability to define methods with the same name but different functionality in different classes?

A) Inheritance
B) Encapsulation
C) Overloading
D) Polymorphism

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14. What is the constructor in OOP?

A) A method called when an object is created
B) A method that deletes objects
C) A function used to access class properties
D) A variable in a class

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15. What is the term for modifying a method in a subclass that already exists in the superclass?

A) Method Overloading
B) Method Overriding
C) Inheritance
D) Polymorphism

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16. Which of the following is a feature of OOP that allows for the definition of new classes based on existing classes?

A) Polymorphism
B) Inheritance
C) Encapsulation
D) Aggregation

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17. What is a method in OOP?

A) A function defined in a class
B) A data member
C) A type of variable
D) A type of loop

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18. What does the term “this” refer to in OOP?

A) The current instance of the class
B) A static method
C) The superclass
D) A global variable

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19. What is dynamic method dispatch in OOP?

A) The process of calling an overridden method at runtime
B) The static allocation of memory
C) The initialization of an object
D) The binding of data

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20. What is an abstract class in OOP?

A) A class that cannot be instantiated
B) A class with no methods
C) A class with only private data members
D) A class with no properties

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21. Which keyword is used to inherit a class in OOP?

A) extends
B) inherits
C) derives
D) subclasses

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22. What is composition in OOP?

A) Creating an object that contains another object
B) Inheriting properties from a superclass
C) Encapsulating methods
D) Creating multiple instances of a class

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23. What does multiple inheritance refer to?

A) A class inheriting from more than one class
B) A class having multiple constructors
C) A class with multiple objects
D) A method with multiple parameters

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24. In OOP, what does the term “getter” refer to?

A) A method used to retrieve the value of a class’s property
B) A method that initializes a class
C) A method used to delete an object
D) A function that creates an object

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25. What is the purpose of an interface in OOP?

A) To define methods that a class must implement
B) To initialize an object
C) To encapsulate data
D) To perform multiple inheritance

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26. What is a destructor in OOP?

A) A method that is invoked when an object is destroyed
B) A method to initialize objects
C) A static variable
D) A method for creating objects

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27. Which of the following is true about static methods in OOP?

A) They belong to the class rather than an instance of the class
B) They can only be accessed through an object
C) They cannot return any value
D) They can only be inherited

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28. What is the use of the ‘super’ keyword in OOP?

A) To call a parent class constructor or method
B) To define a new class
C) To instantiate a class
D) To define a static variable

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29. What is method overriding in OOP?

A) When a subclass provides a specific implementation of a method already defined in the superclass
B) When a class has multiple constructors
C) When methods have the same name but different parameters
D) When a class inherits from another class

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30. What does the term “abstract method” mean in OOP?

A) A method that must be implemented by a subclass
B) A method that has no parameters
C) A method that is hidden from other classes
D) A method that initializes an object

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31. Which OOP concept focuses on reusing existing code?

A) Inheritance
B) Polymorphism
C) Encapsulation
D) Abstraction

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32. What is a virtual function in OOP?

A) A function that can be overridden in derived classes
B) A function that cannot return a value
C) A function without any parameters
D) A function that is always static

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33. Which OOP concept is violated if all data members of a class are made public?

A) Encapsulation
B) Inheritance
C) Polymorphism
D) Abstraction

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34. What is a pure virtual function in OOP?

A) A function declared in a base class but defined in derived classes
B) A function that can be called only once
C) A function with no return type
D) A function that cannot be inherited

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35. Which of the following is true for interfaces in OOP?

A) They can only contain abstract methods
B) They can be instantiated directly
C) They do not support multiple inheritance
D) They cannot contain static methods

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36. What is a default constructor in OOP?

A) A constructor with no parameters
B) A constructor that initializes objects with parameters
C) A method used to define static variables
D) A constructor that returns an object

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37. What is the term for combining data and functions into a single unit in OOP?

A) Encapsulation
B) Inheritance
C) Abstraction
D) Polymorphism

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38. Which keyword is used to prevent a class from being inherited in OOP?

A) final
B) static
C) private
D) sealed

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39. What does a copy constructor do in OOP?

A) Initializes an object using another object of the same class
B) Initializes an object without any parameters
C) Deletes an object
D) Changes the value of a static variable

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40. What is operator overloading in OOP?

A) Defining a new behavior for an existing operator
B) Creating multiple objects at once
C) Defining functions with the same name
D) Adding more methods to a class

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41. What is the use of the ‘final’ keyword in OOP?

A) To prevent method overriding
B) To declare a class
C) To define an abstract method
D) To perform inheritance

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42. In OOP, what is the default access specifier for class members?

A) Private
B) Public
C) Protected
D) Static

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43. Which of the following is true about abstract classes?

A) They can have both abstract and non-abstract methods
B) They cannot have constructors
C) They can be instantiated directly
D) They cannot inherit other classes

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44. What is the purpose of a friend function in OOP?

A) To access private members of a class
B) To initialize an object
C) To define an abstract method
D) To overload operators

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45. What is the difference between an abstract class and an interface in OOP?

A) An abstract class can have method implementations, whereas an interface cannot
B) An interface can have method implementations, but an abstract class cannot
C) Both can be instantiated directly
D) An interface can have constructors

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46. What is the purpose of a constructor in OOP?

A) To initialize an object when it is created
B) To define the attributes of a class
C) To overload operators
D) To destroy an object

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47. What does static binding refer to in OOP?

A) Method call binding done at compile time
B) Method call binding done at runtime
C) Creating objects from a class
D) Overriding methods

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48. What does dynamic binding refer to in OOP?

A) Method call binding done at runtime
B) Method call binding done at compile time
C) Declaring variables in a class
D) Defining static methods

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49. Which of the following refers to runtime polymorphism in OOP?

A) Method overriding
B) Method overloading
C) Operator overloading
D) Static binding

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50. What does the keyword ‘this’ represent in OOP?

A) The current object instance
B) The superclass
C) A static method
D) A global variable

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51. What is the main difference between method overloading and method overriding in OOP?

A) Overloading occurs at compile time, and overriding occurs at runtime
B) Overloading occurs at runtime, and overriding occurs at compile time
C) Both occur at runtime
D) Both occur at compile time

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52. In OOP, which function is responsible for destroying objects?

A) Destructor
B) Constructor
C) Finalizer
D) Friend function

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53. What is the main advantage of using inheritance in OOP?

A) Code reuse
B) Data hiding
C) Improved memory management
D) Enhanced performance

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54. In OOP, what is the term for a class that cannot be instantiated?

A) Abstract class
B) Concrete class
C) Static class
D) Derived class

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55. What is the primary purpose of an interface in OOP?

A) To define a contract for what methods a class must implement
B) To initialize objects
C) To perform operator overloading
D) To provide a constructor for classes

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56. What is the term for a function defined inside a class but outside of any method in OOP?

A) Member function
B) Global function
C) Local function
D) Static function

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57. Which of the following is true for constructors in OOP?

A) They are automatically called when an object is created
B) They cannot accept parameters
C) They cannot be overloaded
D) They cannot be inherited

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58. In OOP, what does the keyword ‘virtual’ indicate?

A) A method can be overridden by a derived class
B) A class is abstract
C) A method is static
D) A constructor is used

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59. What does the term “pure virtual function” mean in OOP?

A) A function that must be implemented by a derived class
B) A function with no parameters
C) A function that cannot be inherited
D) A function that initializes objects

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60. What is the advantage of polymorphism in OOP?

A) It allows for flexibility and extensibility in code
B) It prevents method overloading
C) It hides data from other classes
D) It reduces memory usage

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61. What is the purpose of a static variable in OOP?

A) To maintain a single copy of the variable shared across all objects
B) To initialize objects
C) To destroy objects
D) To define a local variable

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62. What does method overriding allow in OOP?

A) It allows a subclass to provide a specific implementation of a method already defined in the superclass
B) It allows the same method name with different parameters
C) It hides the internal structure of an object
D) It initializes objects

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63. What is the difference between ‘public’ and ‘private’ access modifiers in OOP?

A) Public members can be accessed from outside the class, while private members cannot
B) Private members can be accessed from outside the class, while public members cannot
C) Both provide the same level of access
D) Public members can only be accessed within the class

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64. What does the ‘protected’ keyword indicate in OOP?

A) A member is accessible within its class and by derived class instances
B) A member is accessible only within the class
C) A member is accessible by all objects
D) A member is static

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65. What is the term for creating a new class from an existing class in OOP?

A) Inheritance
B) Encapsulation
C) Abstraction
D) Polymorphism

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66. What is the primary benefit of using encapsulation in OOP?

A) It restricts direct access to some of an object’s components
B) It allows multiple classes to inherit from one class
C) It enables the creation of multiple objects
D) It speeds up code execution

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67. Which of the following allows classes to define methods with the same name but different signatures?

A) Method overloading
B) Method overriding
C) Polymorphism
D) Abstraction

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68. In OOP, what does it mean to overload a method?

A) To create multiple methods with the same name but different parameters
B) To change the access level of a method
C) To prevent a method from being inherited
D) To create a method without parameters

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69. What is the main role of an accessor method in OOP?

A) To retrieve the value of a private variable
B) To change the value of a private variable
C) To destroy an object
D) To create an instance of a class

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70. In OOP, what is the significance of a mutator method?

A) It changes the value of a private variable
B) It accesses a private variable
C) It destroys objects
D) It defines the constructor

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71. What does the term “base class” refer to in OOP?

A) The class from which other classes are derived
B) The class that cannot be inherited
C) The class that contains only abstract methods
D) The class that defines static members

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72. What is the term for multiple classes derived from a single parent class in OOP?

A) Inheritance
B) Multiple inheritance
C) Polymorphism
D) Abstraction

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73. What is the key characteristic of a static method in OOP?

A) It belongs to the class rather than any object of the class
B) It can only be called once in a program
C) It must be overridden by a subclass
D) It cannot access any class members

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74. What is the term for hiding the implementation details of a class in OOP?

A) Abstraction
B) Encapsulation
C) Inheritance
D) Polymorphism

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75. In OOP, what does the term “derived class” mean?

A) A class that inherits properties and methods from another class
B) A class that cannot be inherited
C) A class that defines abstract methods
D) A class that only has static methods

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76. What does ‘instance of’ operator check in OOP?

A) If an object is an instance of a particular class
B) If a class contains static methods
C) If a method is abstract
D) If two classes are related

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77. What is an interface in OOP used for?

A) To define methods that must be implemented by derived classes
B) To create static methods
C) To instantiate objects
D) To define private variables

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78. In OOP, what is method hiding?

A) When a derived class defines a method with the same name as one in its base class but without overriding it
B) When a method is made private
C) When a method is overloaded
D) When a method is static

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79. What is the primary purpose of polymorphism in OOP?

A) To allow one interface to be used for a general class of actions
B) To prevent methods from being overloaded
C) To destroy objects in memory
D) To hide the details of method implementation

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80. What is the primary difference between overloading and overriding in OOP?

A) Overloading involves different method signatures, while overriding involves redefining a method in a subclass
B) Overloading occurs in derived classes, while overriding occurs in base classes
C) Overriding only applies to static methods
D) Overloading cannot be done within the same class

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81. In OOP, what does the ‘protected’ access modifier allow?

A) Access within the same class and by derived classes
B) Access only within the class where it is defined
C) Access by any class in the program
D) Access only by external libraries

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82. What does the term “method signature” refer to in OOP?

A) The combination of the method’s name and parameter types
B) The return type of a method
C) The access level of a method
D) The method’s position in the class hierarchy

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83. What is the term for a class that cannot be instantiated directly?

A) Abstract class
B) Derived class
C) Static class
D) Sealed class

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84. In OOP, which keyword is used to refer to the superclass of a subclass?

A) super
B) this
C) static
D) virtual

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85. Which of the following is an example of compile-time polymorphism in OOP?

A) Method overloading
B) Method overriding
C) Dynamic binding
D) Inheritance

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86. What is the purpose of a destructor in OOP?

A) To destroy an object when it is no longer needed
B) To create objects dynamically
C) To overload methods
D) To initialize class members

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87. What is a sealed class in OOP?

A) A class that cannot be inherited
B) A class that must be instantiated
C) A class that can only be inherited once
D) A class that can only define static methods

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88. What is the key characteristic of an abstract method in OOP?

A) It has no implementation and must be implemented in derived classes
B) It can be called directly from the base class
C) It is always static
D) It must return a value

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89. Which of the following is a feature of dynamic polymorphism in OOP?

A) Method overriding
B) Method overloading
C) Operator overloading
D) Static binding

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90. What is the purpose of a copy constructor in OOP?

A) To create a new object as a copy of an existing object
B) To create objects without parameters
C) To overload operators
D) To initialize static variables

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91. In OOP, what does the term ‘namespace’ refer to?

A) A container that holds a logical grouping of related classes
B) The memory space where objects are created
C) A way to call static methods
D) A type of inheritance

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92. Which of the following is a characteristic of static polymorphism in OOP?

A) Method overloading
B) Method overriding
C) Inheritance
D) Interface implementation

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93. What does the term ‘constructor overloading’ mean in OOP?

A) Defining multiple constructors with different parameters
B) Redefining a constructor in a subclass
C) Using a constructor without parameters
D) Destroying objects created by a constructor

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94. What does the keyword ‘this’ represent in OOP?

A) The current instance of a class
B) A static variable
C) The superclass of an object
D) A global variable

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95. What is the advantage of using a virtual function in OOP?

A) It allows a function to be overridden in derived classes
B) It prevents method overloading
C) It defines static methods
D) It ensures a function cannot be modified

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96. What is the term for a variable that is shared by all instances of a class in OOP?

A) Static variable
B) Local variable
C) Instance variable
D) Global variable

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97. In OOP, what is the primary function of the ‘final’ keyword?

A) It prevents a class from being inherited
B) It defines a static method
C) It allows method overloading
D) It defines an abstract method

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98. What does the keyword ‘super’ refer to in OOP?

A) The parent class
B) The current instance of a class
C) A static method
D) An overloaded method

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99. What is the purpose of the ‘new’ keyword in OOP?

A) To allocate memory for a new object
B) To destroy an object
C) To define an abstract class
D) To override a method

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100. Which of the following best describes method overriding in OOP?

A) Redefining a method in a subclass that already exists in the superclass
B) Defining multiple methods with the same name but different parameters
C) Preventing a method from being inherited
D) Defining a method as static

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