250+ TOP MCQs on Inheritance and Answers

Object Oriented Programming (OOPs) Multiple Choice Questions & Answers (MCQs) on “Inheritance”.

1. Which among the following best describes the Inheritance?
a) Copying the code already written
b) Using the code already written once
c) Using already defined functions in programming language
d) Using the data and functions into derived segment
Answer: d
Clarification: It can only be indicated by using the data and functions that we use in derived class, being provided by parent class. Copying code is nowhere similar to this concept, also using the code already written is same as copying. Using already defined functions is not inheritance as we are not adding any of our own features.

2. How many basic types of inheritance are provided as OOP feature?
a) 4
b) 3
c) 2
d) 1
Answer: a
Clarification: There are basically 4 types of inheritance provided in OOP, namely, single level, multilevel, multiple and hierarchical inheritance. We can add one more type as Hybrid inheritance but that is actually the combination any types of inheritance from the 4 basic ones.

3. Which among the following best defines single level inheritance?
a) A class inheriting a derived class
b) A class inheriting a base class
c) A class inheriting a nested class
d) A class which gets inherited by 2 classes
Answer: b
Clarification: A class inheriting a base class defines single level inheritance. Inheriting an already derived class makes it multilevel inheritance. And if base class is inherited by 2 other classes, it is multiple inheritance.

4. Which among the following is correct for multiple inheritance?
a) class student{public: int marks;}s; class stream{int total;}; class topper:public student, public stream{ };
b) class student{int marks;}; class stream{ }; class topper: public student{ };
c) class student{int marks;}; class stream:public student{ };
d) class student{ }; class stream{ }; class topper{ };
Answer: a
Clarification: Class topper is getting derived from 2 other classes and hence it is multiple inheritance. Topper inherits class stream and class student publicly and hence can use its features. If only few classes are defined, there we are not even using inheritance (as in option class student{ }; class stream{ }; class topper{ };).

5. Which programming language doesn’t support multiple inheritance?
a) C++ and Java
b) C and C++
c) Java and SmallTalk
d) Java
Answer: d
Clarification: Java doesn’t support multiple inheritance. But that feature can be implemented by using the interfaces concept. Multiple inheritance is not supported because of diamond problem and similar issues.

6. Which among the following is correct for a hierarchical inheritance?
a) Two base classes can be used to be derived into one single class
b) Two or more classes can be derived into one class
c) One base class can be derived into other two derived classes or more
d) One base class can be derived into only 2 classes
Answer: c
Clarification: One base class can be derived into the other two derived classes or more. If only one class gets derived by only 2 other classes, it is also hierarchical inheritance, but it is not a mandatory condition, because any number of derived classes can be there.

7. Which is the correct syntax of inheritance?
a) class derived_classname : base_classname{ /*define class body*/ };
b) class base_classname : derived_classname{ /*define class body*/ };
c) class derived_classname : access base_classname{ /*define class body*/ };
d) class base_classname :access derived_classname{ /*define class body*/ };
Answer: c
Clarification: Firstly, keyword class should come, followed by the derived class name. Colon is must followed by access in which base class has to be derived, followed by the base class name. And finally the body of class. Semicolon after the body is also must.

8. Which type of inheritance leads to diamond problem?
a) Single level
b) Multi-level
c) Multiple
d) Hierarchical
Answer: c
Clarification: When 2 or more classes inherit the same class using multiple inheritance and then one more class inherits those two base classes, we get a diamond like structure. Here, ambiguity arises when same function gets derived into 2 base classes and finally to 3rd level class because same name functions are being inherited.

9. Which access type data gets derived as private member in derived class?
a) Private
b) Public
c) Protected
d) Protected and Private
Answer: a
Clarification: It is a rule, that when a derived class inherits the base class in private access mode, all the members of base class gets derived as private members of the derived class.

10. If a base class is inherited in protected access mode then which among the following is true?
a) Public and Protected members of base class becomes protected members of derived class
b) Only protected members become protected members of derived class
c) Private, Protected and Public all members of base, become private of derived class
d) Only private members of base, become private of derived class
Answer: a
Clarification: As the programming language rules apply, all the public and protected members of base class becomes protected members of derived class in protected access mode. It can’t be changed because it would hinder the security of data and may add vulnerability in the program.

11. Members which are not intended to be inherited are declared as ________________
a) Public members
b) Protected members
c) Private members
d) Private or Protected members
Answer: c
Clarification: Private access specifier is the most secure access mode. It doesn’t allow members to be inherited. Even Private inheritance can only inherit protected and public members.

12. While inheriting a class, if no access mode is specified, then which among the following is true? (in C++)
a) It gets inherited publicly by default
b) It gets inherited protected by default
c) It gets inherited privately by default
d) It is not possible
Answer: c
Clarification: If the access mode is not specified during inheritance, the class is inherited privately by default. This is to ensure the security of data and to maintain OOP features. Hence it is not mandatory to specify the access mode if we want the class to be inherited privately.

13. If a derived class object is created, which constructor is called first?
a) Base class constructor
b) Derived class constructor
c) Depends on how we call the object
d) Not possible
Answer: a
Clarification: First the base class constructor is invoked. When we create a derived class object, the system tries to invoke its constructor but the class is derived so first the base class must be initialized, hence in turn the base class constructor is invoked before the derived class constructor.

14. The private members of the base class are visible in derived class but are not accessible directly.
a) True
b) False
Answer: a
Clarification: Consider that a variable is private in base class and the derived class uses public inheritance to inherit that class. Now if we also have a global variable of same name as that of base class private variable, neither the global variable nor the base class private variable will be accessible from derived class. This is because we can’t have 2 variables with same name in same local scope. Hence the private members are accessible but not directly.

15. How can you make the private members inheritable?
a) By making their visibility mode as public only
b) By making their visibility mode as protected only
c) By making their visibility mode as private in derived class
d) It can be done both by making the visibility mode public or protected
Answer: d
Clarification: It is not mandatory that you have to make the visibility mode either public or protected. You can do either of those. That will give you permission to inherit the private members of base class.