OOPS Interview Questions and Answers in 2025 (100+ Q&A)

OOPS

Ques:- What is the difference between interface and abstract class?

Asked In :-

Right Answer:
An interface can only declare methods (without implementation) and constants, while an abstract class can have both abstract methods (without implementation) and concrete methods (with implementation). Additionally, a class can implement multiple interfaces but can inherit from only one abstract class.

C MySQL OOPS Software Engineer

Ques:- What are the access specifiers?

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Right Answer:
Access specifiers are keywords used in object-oriented programming to set the accessibility of classes, methods, and other members. The main access specifiers are:

1. **Public**: Members are accessible from any part of the program.
2. **Private**: Members are accessible only within the class itself.
3. **Protected**: Members are accessible within the class and by derived class instances.

OOPS

Ques:- Which OOPS concept exposes only necessary information to the calling functions?

Asked In :-

Right Answer:
Encapsulation.

Comments

Murli Ramlubhai Pillamari Sep 3, 2020

many of you saying abstraction, but the answer is Encapsulation.

Akash chourasia Dec 15, 2019

Abstract class

OOPS

Ques:- Which OOPS concept is used as reuse mechanism?

Asked In :-

Right Answer:
Inheritance

Comments

Y.likhitha Oct 26, 2019

Inheritance

OOPS

Ques:- What is the default access specifier in a class definition?

Asked In :-

Right Answer:
The default access specifier in a class definition is "private."

OOPS

Ques:- Which keyword can be used for overloading?

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Right Answer:
The keyword used for overloading is "operator."

Comments

DK BOSS Jul 21, 2021

// Overload ++ when used as prefix

#include
using namespace std;

class Count {
private:
int value;

public:

// Constructor to initialize count to 5
Count() : value(5) {}

// Overload ++ when used as prefix
void operator ++ () {
++value;
}

void display() {
cout << "Count: " << value << endl;
}
};

int main() {
Count count1;

// Call the "void operator ++ ()" function
++count1;

count1.display();
return 0;
}

OOPS

Ques:- How many instances can be created for an abstract class?

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Right Answer:
No instances can be created for an abstract class.

OOPS

Ques:- What is static and dynamic binding?

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Right Answer:
Static binding (or early binding) occurs at compile time, where the method to be called is determined based on the reference type. Dynamic binding (or late binding) occurs at runtime, where the method to be called is determined based on the actual object type.

OOPS

Ques:- What is a base class, sub class, and super class?

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Right Answer:
A base class is a class that provides common attributes and methods for other classes. A subclass is a class that inherits from a base class, gaining its properties and behaviors. A superclass is another term for the base class, referring to the class from which subclasses derive.

OOPS

Ques:- Whether static method can use nonstatic members?

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Right Answer:
No, a static method cannot directly use non-static members.

OOPS

Ques:- What does the keyword virtual represented in the method definition?

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Right Answer:
The keyword `virtual` in a method definition indicates that the method can be overridden in a derived class, allowing for polymorphic behavior.

OOPS

Ques:- What is a copy constructor?

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Right Answer:
A copy constructor is a special type of constructor in object-oriented programming that initializes a new object as a copy of an existing object of the same class. It typically takes a reference to an object of the same class as an argument.

OOPS

Ques:- Do we require a parameter for constructors?

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Right Answer:
No, constructors do not require parameters; they can be defined without any.

OOPS

Ques:- What is dynamic or run time polymorphism?

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Right Answer:
Dynamic or run-time polymorphism is a feature in object-oriented programming where a method can perform different functions based on the object that it is acting upon, typically achieved through method overriding. This allows the program to determine which method to execute at runtime rather than at compile time.

OOPS

Ques:- What are all the operators that cannot be overloaded?

Asked In :-

Right Answer:
The operators that cannot be overloaded are:

1. Scope resolution operator (::)
2. Member selector operator (.)
3. Member pointer selector operator (.*)
4. Sizeof operator
5. Conditional operator (?:)
6. Typeid operator
7. Alignof operator (C++11 and later)
8. New and delete operators (global new and delete cannot be overloaded, but class-specific ones can)

OOPS

Ques:- What is a pure virtual function?

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Right Answer:
A pure virtual function is a function declared in a base class that has no implementation and is specified by assigning `0` in its declaration. It makes the class abstract, meaning it cannot be instantiated directly and must be overridden in derived classes.

OOPS

Ques:- What is the default access modifier in a class?

Asked In :-

Right Answer:
The default access modifier in a class is "package-private" (or "default"), meaning the class is accessible only within its own package.

OOPS

Ques:- What is the difference between structure and a class?

Asked In :-

Right Answer:
The main differences between a structure and a class are:

1. **Default Access Modifier**: In a structure, members are public by default, while in a class, they are private by default.
2. **Inheritance**: Classes support inheritance, allowing for derived classes, whereas structures do not support inheritance.
3. **Memory Allocation**: Structures are typically allocated on the stack, while classes are allocated on the heap.

OOPS

Ques:- What is Ã¢â‚¬ËœthisÃ¢â‚¬â„¢ pointer?

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Right Answer:
The `this` pointer is a special pointer in C++ that refers to the current object instance within a class's member function. It allows access to the object's members and methods.

Comments

DK BOSS Jul 21, 2021

i can not understand this language

OOPS

Ques:- What is early and late binding?

Asked In :-

Right Answer:
Early binding refers to the compile-time association of a method call to the method definition, meaning the method to be invoked is determined during compilation. Late binding, on the other hand, refers to the runtime association of a method call to the method definition, allowing for more flexibility, such as method overriding in polymorphism.

The OOPS (Object-Oriented Programming Systems) category on takluu.com is designed for software developers and programming aspirants who want to strengthen their understanding of object-oriented principles. OOPS is a fundamental programming paradigm used widely across many languages such as Java, C++, Python, and more.

This section covers essential concepts including classes and objects, encapsulation, inheritance, polymorphism, abstraction, and interfaces. You’ll find interview questions that focus on both theory and practical application of these principles in real-world coding scenarios.

Interviewers often ask questions like:

“Explain the four pillars of OOPS.”
“How does inheritance promote code reusability?”
“What is polymorphism and how is it implemented?”

Our content presents these concepts in a simple and clear manner, supported by examples and coding snippets to help you grasp them easily. Whether you’re a beginner or preparing for advanced technical interviews, this category helps you build a strong foundation and confidently tackle OOPS-related questions.

At Takluu, we regularly update the OOPS category with new questions, coding challenges, and best practices to keep you ahead in your interview preparation journey.

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