Top 30+ OOPS Real Time Interview Questions

 

OOP languages are embedded languages that support OOP principles such as encapsulation, inheritance, polymorphism, and abstraction. Now let’s take a look at the following example OOP languages:

Popular OOP Languages:

Top 30+ OOPS Real Time Interview Questions

 

Here’s a tabular comparison of popular OOP languages based on key features:

Language	Fully OOP?	Primary Use Case	Multi-Paradigm Support	Memory Management	Platform	Notable Features
C++	No (Hybrid)	System Programming, Game Dev	Yes (OOP + Procedural)	Manual (with smart pointers)	Cross-platform	Fast performance, multiple inheritance
Java	Yes	Enterprise, Web, Android	Yes (OOP + Functional)	Automatic (Garbage Collection)	Cross-platform (JVM)	Strong type safety, rich libraries
Python	Yes	Web, AI, Scripting	Yes (OOP + Functional + Procedural)	Automatic (Garbage Collection)	Cross-platform	Dynamic typing, simplicity
C#	Yes	.NET, Game Dev (Unity)	Yes (OOP + Functional)	Automatic (Garbage Collection)	Windows, Cross-platform (via .NET)	Strong integration with Microsoft ecosystem
JavaScript	No (Prototype-based OOP)	Web Dev, Backend (Node.js)	Yes (Functional + OOP)	Automatic	Cross-platform (Browser, Node.js)	Prototype inheritance, event-driven
Swift	Yes	iOS/macOS Apps	Yes (OOP + Functional)	Automatic (ARC)	Apple Ecosystem	Type safety, modern syntax
Kotlin	Yes	Android, Backend	Yes (OOP + Functional)	Automatic (GC)	Cross-platform (JVM, Native)	Concise, null safety
Ruby	Yes	Web Dev (Rails)	Yes (OOP + Metaprogramming)	Automatic (GC)	Cross-platform	Everything is an object
PHP	No (Hybrid)	Web Dev (Backend)	Yes (Procedural + OOP)	Automatic (GC)	Web Servers	Easy to learn, wide adoption
Objective-C	Yes	iOS/macOS (Legacy)	Yes (OOP + Procedural)	Automatic (ARC)	Apple Ecosystem	Message-passing, influenced by Smalltalk

 

 

Top 30+ OOPS Real Time Interview Questions

1. 4 Pillars of OOPS?
2. What are Class and object?
3. What is Abstraction?
4. What is Encapsulation?
5. What is Inheritance?
6. Types of Inheritance?
7. Diamond Problem?
8. What is Polymorphism and its types?
9. What is Compile-time polymorphism?
10.  What are Function Overloading and Operator Overloading?
11.  What is New Operator and Delete Operator?
12. What is Run Time Polymorphism?
13.  What are VTable and VPtr?
14.  What is a Constructor?
15.  Types of Constructors?
16.  Write your own copy constructor and own assignment operator.
17.  What is Move Constructor?
18.  Write your own move constructor and own move assignment operator. 
19.  What are Destructors?
20.  What is a Virtual Destructor?
21.  What are Const Variables and How do initialize in constructors?
22.  What are Static Variables and Static Methods?
23.  What is Friend Functions?
24.  What are Smart Pointers?
25.  What are weak Pointers, and shared Pointers?
26.  Types Of Casting?
27.  What are Dynamic Casting and Static Casting?
28.  What is Object Slicing?
29.  What is the use of an Explicit Keyword?
30.  What is a Function Pointer?
31.  2D array Initiation?
32.  Write Your Own Vector?
33.  What are lambda functions?

Here’s a tabular format covering all your OOPs concepts in a structured manner:

Top 30+ OOPS Real Time Interview Questions

for JAVA ,C++,PYTHON etc

Concept	Explanation
4 Pillars of OOP	Encapsulation, Abstraction, Inheritance, Polymorphism
Abstraction	Hiding implementation details and showing only the necessary features to the user (e.g., using abstract classes and interfaces).
Encapsulation	Wrapping data and functions into a single unit (class) and restricting direct access using access modifiers (private, protected, public).
Inheritance	Mechanism where a class (child) derives properties and behaviors from another class (parent). Promotes code reusability.
Types of Inheritance	– Single (one parent → one child) – Multiple (one child inherits multiple parents) – Multilevel (grandparent → parent → child) – Hierarchical (one parent → multiple children) – Hybrid (combination of multiple inheritance types)
Diamond Problem	Occurs in multiple inheritance when a child class inherits from two classes that share a common base class, causing ambiguity. Solved using virtual inheritance in C++.
Polymorphism	Ability of an entity (method or operator) to take multiple forms. Two types: Compile-time (early binding) and Run-time (late binding).
Compile-time Polymorphism	Achieved using function overloading and operator overloading where function calls are resolved at compile-time.
Function Overloading	Defining multiple functions with the same name but different parameters (different number or type of arguments).
Operator Overloading	Redefining operators (+, -, *, =, etc.) to work with user-defined types (classes).
New and Delete Operators	new dynamically allocates memory for objects, delete deallocates it. Example: int* p = new int(5); delete p;
Run-time Polymorphism	Achieved through method overriding and virtual functions, resolved at runtime using dynamic binding (vtable mechanism).
VTable & VPtr	– VTable (Virtual Table): Table storing addresses of virtual functions. – VPtr (Virtual Pointer): Pointer to VTable, maintained per object to resolve function calls dynamically.
Constructor	Special function executed when an object is created. Used for initialization.
Types of Constructors	– Default (no arguments) – Parameterized (with arguments) – Copy (creates a new object as a copy of an existing object) – Move (optimizes resource transfer in temporary objects)
Copy Constructor	ClassName(const ClassName &obj) { /* copy logic */ }
Assignment Operator (Overloaded)	ClassName& operator=(const ClassName &obj) { /* assignment logic */ return *this; }
Move Constructor	ClassName(ClassName&& obj) { /* move logic */ }
Move Assignment Operator	ClassName& operator=(ClassName&& obj) { /* move assignment logic */ return *this; }
Destructors	Special function (~ClassName()) called when an object goes out of scope to free resources.
Virtual Destructor	Ensures derived class destructor is called first in polymorphic scenarios. virtual ~ClassName() {}
Const Variables in Constructor	Initialized using an initializer list: ClassName() : myConstVar(10) {}
Static Variables & Methods	– Static Variables: Shared among all instances of a class. – Static Methods: Can be called without an object (ClassName::method()).
Friend Functions	Non-member function that can access private/protected members of a class (friend keyword).
Smart Pointers	unique_ptr, shared_ptr, and weak_ptr manage memory automatically.
Weak & Shared Pointers	– Shared Pointer (shared_ptr): Reference-counted ownership. – Weak Pointer (weak_ptr): Non-owning reference to prevent cyclic dependencies.
Types of Casting	– static_cast (compile-time type conversion) – dynamic_cast (safe downcasting) – const_cast (removes const qualifier) – reinterpret_cast (converts pointer types)
Dynamic vs Static Casting	– Static Casting (static_cast): Compile-time conversion. – Dynamic Casting (dynamic_cast): Used for polymorphism, checks type safety at runtime.
Object Slicing	When a derived class object is assigned to a base class object, the extra properties of the derived class are sliced off.
Explicit Keyword	Prevents implicit conversions when using single-parameter constructors. explicit ClassName(int x);
Function Pointer	A pointer that stores the address of a function. Example: void (*ptr)() = &func;
2D Array Initialization	int arr[3][3] = {{1,2,3}, {4,5,6}, {7,8,9}};
Write Your Own Vector	Implement dynamic array with push_back, pop_back, resize, etc.
Lambda Functions	Anonymous functions used for short, inline operations. Syntax: [capture](parameters) { body }

Top 30+ OOPS Real Time Interview Questions

Follow us on

http://www.youtube.com/@TrendyVSVlogs

http://www.youtube.com/@VSCodingAcademy