Are you preparing for an Object-Oriented Programming (OOPs) interview? Whether you're a fresher or an experienced professional, mastering OOPs concepts is essential to crack your dream job. Here’s a comprehensive list of the top 50 OOPs interview questions and answers to help you ace your next interview!
1. What is OOPS?
OOPS stands for Object-Oriented Programming System, where programs are organized as a collection of objects. Each object is an instance of a class and encapsulates both data and behavior.
2. What are the basic concepts of OOPS?
The four key concepts of OOPS are:
Abstraction
Encapsulation
Inheritance
Polymorphism
3. What is a Class?
A class is a blueprint or template that defines the properties and behaviors of objects.
4. What is an Object?
An object is an instance of a class that contains its own identity, state, and behavior.
5. What is Encapsulation?
Encapsulation is a mechanism that binds data and the code that manipulates it together while keeping it safe from outside interference.
6. What is Polymorphism?
Polymorphism means the ability of an object to take many forms. It enables the same function or operator to behave differently based on the context.
7. What is Inheritance?
Inheritance is a mechanism where a class (child class) can acquire properties and behavior from another class (parent class).
8. What are Manipulators?
Manipulators are functions used with insertion (<<) and extraction (>>) operators in C++. Examples include endl and setw.
9. Explain the term Constructor.
A constructor is a special method that initializes an object when it is created. Rules:
The constructor name should be the same as the class name.
It does not have a return type.
10. What is a Destructor?
A destructor is a special method called automatically when an object goes out of scope or is deleted.
11. What is an Inline Function?
An inline function is a function whose complete body is inserted wherever it is called, reducing function call overhead.
12. What is a Virtual Function?
A virtual function is a member function in a base class that can be overridden by derived classes.
13. What is a Friend Function?
A friend function is a function that is not a member of a class but has access to its private and protected members.
14. What is Function Overloading?
Function overloading allows multiple functions to have the same name but different parameters.
15. What is Operator Overloading?
Operator overloading enables operators like +, -, * to be used with user-defined data types.
16. What is an Abstract Class?
An abstract class cannot be instantiated and must be inherited by subclasses.
17. What is a Ternary Operator?
A ternary operator is a conditional operator that takes three arguments: condition ? value_if_true : value_if_false;
18. What is the use of the finalize() method?
The finalize() method is used for resource cleanup before garbage collection.
19. What are the different types of arguments?
Call by Value: Changes inside the function do not affect the original value.
Call by Reference: Changes inside the function affect the original value.
20. What is the Super Keyword?
The super keyword is used to call methods from a superclass in Java.
21. What is Method Overriding?
Method overriding allows a subclass to provide a different implementation of a method inherited from a parent class.
22. What is an Interface?
An interface is a collection of abstract methods that must be implemented by a class.
23. What is Exception Handling?
Exception handling manages runtime errors using mechanisms like try, catch, and throw.
24. What are Tokens?
Tokens are the smallest elements recognized by the compiler, such as keywords, constants, and operators.
25. Difference Between Overloading and Overriding?
Overloading is static binding (compile-time) where multiple methods have the same name but different parameters.
Overriding is dynamic binding (runtime) where a subclass provides a specific implementation of a parent method.
26. What is the difference between Class and Object?
Class: A blueprint or template.
Object: An instance of a class.
27. What is Abstraction?
Abstraction hides complex implementation details and only shows the necessary features.
28. What are Access Modifiers?
Access Modifiers define the scope of variables and methods:
Private
Protected
Public
Friend
ProtectedFriend
29. What are Sealed Modifiers?
Sealed modifiers prevent methods from being inherited.
30. Can we call a base method without creating an instance?
Yes, using static methods or inheritance with the base keyword.
31. Difference Between New and Override?
newcreates a new method in a subclass.overridemodifies an inherited method.
32. Types of Constructors?
Default Constructor
Parameterized Constructor
Copy Constructor
33. What is Early and Late Binding?
Early Binding: Resolves method calls at compile-time.
Late Binding: Resolves method calls at runtime.
34. What is the this Pointer?
this pointer refers to the current object of the class.
35. Difference Between Structure and Class?
Structure: Default access is public, used for grouping data.
Class: Default access is private, supports encapsulation.
36. Default Access Modifier in a Class?
Class: Internal
Class Members: Private
37. What is a Pure Virtual Function?
A function declared as = 0 in C++ that must be implemented by derived classes.
38. Operators That Cannot Be Overloaded?
Scope Resolution (::)
Member Selection (.)
Pointer-to-Member Selection (.*)
39. What is Runtime Polymorphism?
Runtime polymorphism, or method overriding, resolves function calls at runtime.
40. Is a Constructor Parameter Required?
No, constructors can be parameterless.
41-50. More OOPS Questions!
From copy constructors to encapsulation, continue practicing these essential concepts to master OOPS!
