Top Important OOPs Interview Questions and Answers
Basic OOPs Interview Questions
1. What is the difference between OOP and SOP?
2. What is Object Oriented Programming?
Object-Oriented Programming(OOPs) is a type of programming that is based on objects rather than just functions and procedures. Individual objects are grouped into classes. OOPs implements real-world entities like inheritance, polymorphism, hiding, etc into programming. It also allows binding data and code together.Read More Dotnet Online training
3. Why use OOPs?
- OOPs allows clarity in programming thereby allowing simplicity in solving complex problems
- Code can be reused through inheritance thereby reducing redundancy
- Data and code are bound together by encapsulation
- OOPs allows data hiding, therefore, private data is kept confidential
- Problems can be divided into different parts making it simple to solve
- The concept of polymorphism gives flexibility to the program by allowing the entities to have multiple forms
4. What are the main features of OOPs?
Classes and Objects OOPs Interview Questions
5. What is an object?
An object is a real-world entity which is the basic unit of OOPs for example chair, cat, dog, etc. Different objects have different states or attributes, and behaviors.Know More Dotnet Online Course
6. What is a class?
A class is a prototype that consists of objects in different states and with different behaviors. It has a number of methods that are common the objects present within that class.
7. What is the difference between a class and a structure?
Class: User-defined blueprint from which objects are created. It consists of methods or set of instructions that are to be performed on the objects.
Structure: A structure is basically a user-defined collection of variables which are of different data types.
8. Can you call the base class method without creating an instance?
Yes, you can call the base class without instantiating it if:
- It is a static method
- The base class is inherited by some other subclass Know More Dotnet Training
9. What is the difference between a class and an object?
OOPs Interview Questions – Inheritance
10. What is inheritance?
Inheritance is a feature of OOPs which allows classes inherit common properties from other classes. For example, if there is a class such as ‘vehicle’, other classes like ‘car’, ‘bike’, etc can inherit common properties from the vehicle class. This property helps you get rid of redundant code thereby reducing the overall size of the code.
11. What are the different types of inheritance?
- Single inheritance
- Multiple inheritance
- Multilevel inheritance
- Hierarchical inheritance
- Hybrid inheritance
12. What is the difference between multiple and multilevel inheritance?
| Multiple Inheritance | Multilevel Inheritance |
| Multiple inheritance comes into picture when a class inherits more than one base class | Multilevel inheritance means a class inherits from another class which itself is a subclass of some other base class |
| Example: A class defining a child inherits from two base classes Mother and Father | Example: A class describing a sports car will inherit from a base class Car which inturn inherits another class Vehicle |
13. What is hybrid inheritance?
Hybrid inheritance is a combination of multiple and multi-level inheritance.Know More Dotnet Online Training
14. What is hierarchical inheritance?
Hierarchical inheritance refers to inheritance where one base class has more than one subclasses. For example, the vehicle class can have ‘car’, ‘bike’, etc as its subclasses.
15. What are the limitations of inheritance?
- Increases the time and effort required to execute a program as it requires jumping back and forth between different classes
- The parent class and the child class get tightly coupled
- Any modifications to the program would require changes both in the parent as well as the child class
- Needs careful implementation else would lead to incorrect result
16. What is a superclass?
A superclass or base class is a class that acts as a parent to some other class or classes. For example, the Vehicle class is a superclass of class Car.Know More Dotnet Training
17. What is a subclass?
A class that inherits from another class is called the subclass. For example, the class Car is a subclass or a derived of Vehicle class.
OOPs Interview Questions – Polymorphism
18. What is polymorphism?
Polymorphism refers to the ability to exist in multiple forms. Multiple definitions can be given to a single interface. For example, if you have a class named Vehicle, it can have a method named speed but you cannot define it because different vehicles have different speed. This method will be defined in the subclasses with different definitions for different vehicles.
19. What is static polymorphism?
Static polymorphism (static binding) is a kind of polymorphism that occurs at compile time. An example of compile-time polymorphism is method overloading.
20. What is dynamic polymorphism?
Runtime polymorphism or dynamic polymorphism (dynamic binding) is a type of polymorphism which is resolved during runtime. An example of runtime polymorphism is method overriding.
21. What is method overloading?
Method overloading is a feature of OOPs which makes it possible to give the same name to more than one methods within a class if the arguments passed differ.
22. What is method overriding?
Method overriding is a feature of OOPs by which the child class or the subclass can redefine methods present in the base class or parent class. Here, the method that is overridden has the same name as well as the signature meaning the arguments passed and the return type.
23. What is operator overloading?
Operator overloading refers to implementing operators using user-defined types based on the arguments passed along with it.Know More Dotnet Online Course
24. Differentiate between overloading and overriding.
| Overloading | Overriding |
| Two or more methods having the same name but different parameters or signature | Child class redefining methods present in the base class with the same parameters/ signature |
| Resolved during compile-time | Resolved during runtime |
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