Master C++ Interview Questions and Answers for Freshers 2025

C++ interview questions – C++ is a powerful object-oriented programming language widely used in system programming, game development, and high-performance applications. Employers frequently assess a candidate’s understanding of core C++ concepts, such as object-oriented principles, data structures, and memory management, during technical interviews. Preparing for C++ interview questions can significantly improve your chances of success by showcasing your expertise and problem-solving skills.

Whether you’re applying for entry-level or experienced roles, these questions often focus on practical implementation and theoretical understanding, ensuring you can handle real-world challenges.

In this guide, we’ll explore some frequently asked C++ interview questions to help you ace your next interview!

Join Our WhatsApp Community	CLICK HERE
Join Our Instagram Community	CLICK HERE

1) What is C++?

C++ is a high-level, object-oriented programming language developed by Bjarne Stroustrup and first released in 1985.

It is an extension of the C language, with the key addition of classes to support object-oriented programming. Initially named “C with Classes,” it was later renamed C++, inspired by the C increment operator ++, symbolizing the language’s enhancement over C.

C++ is widely used for system programming, game development, and applications requiring high performance and efficiency. This is a common topic in C++ interview questions.

2) What are the advantages of C++?

C++ combines the power of C with additional features that make programming more efficient and versatile. Some key advantages include:

• Portability: Programs written in C++ can run on various platforms without modification.
• Object-Oriented Programming: C++ supports classes, objects, inheritance, polymorphism, and abstraction, making it ideal for modular and scalable code.
• Code Reusability: The concept of inheritance allows the reuse of existing code, reducing redundancy.
• Data Security: Data hiding enables the creation of secure programs, protecting sensitive information from unauthorized access.
• Efficient Communication: Message passing facilitates communication between objects, enhancing modular design.
• Rich Function Library: C++ offers an extensive standard library, simplifying complex programming tasks.

These features make C++ a powerful tool for developing high-performance applications.

3) What is the difference between C and C++?

Here are the key differences between C and C++:

Aspect	C	C++
Developer	Dennis Ritchie	Bjarne Stroustrup
Programming Paradigm	Structured programming	Supports both structured and object-oriented programming
Relationship	C is a subset of C++.	C++ is a superset of C.
Encapsulation	Data and functions are separate.	Data and functions are encapsulated in objects.
Data Hiding	Does not support data hiding.	Supports data hiding to secure information.
Overloading	Does not support function and operator overloading.	Supports both function and operator overloading.
Functions in Structures	Functions cannot be implemented inside structures.	Functions can be implemented inside structures.
Reference Variables	Does not support reference variables.	Supports reference variables.
Special Functions	Does not support virtual and friend functions.	Supports both virtual and friend functions.
Input/Output	Uses scanf() and printf() for input/output.	Uses cin and cout for input/output.

These differences make C++ more versatile, especially for applications requiring modularity and object-oriented design. This is a common topic in C++ interview questions.

4) What is the difference between a reference and a pointer?

Here are the key differences between a reference and a pointer:

Aspect	Reference	Pointer
Definition	Acts as an alias for an existing variable.	A variable that stores the memory address of another variable.
Accessing Value	Can access the value directly without using an indirection operator.	Requires an indirection operator (*) to access the value.
Reassignment	Cannot be reassigned to refer to another variable after initialization.	Can be reassigned to point to different objects.
Null Assignment	Cannot hold a null value.	Can hold a null value.
Initialization	Must be initialized at the time of declaration.	Initialization is not mandatory at the time of declaration.

Example:

Reference:

int a = 10;
int &ref = a; // Reference
ref = 20;     // Changes value of 'a' to 20

Pointer:

int a = 10;
int *ptr = &a; // Pointer
*ptr = 20;     // Changes value of 'a' to 20

These differences make references more restrictive and safer compared to pointers, while pointers are more flexible and powerful.

5) Define Token in C++

In C++, a token is the smallest individual unit of a program. Tokens serve as the building blocks of a C++ program and are categorized into different types.

Types of Tokens in C++:

1. Keywords: Reserved words that have a special meaning in the language (e.g., int, class, if, else).
2. Identifiers: Names given to variables, functions, arrays, etc., defined by the programmer.
3. Literals: Fixed values assigned to variables (e.g., 10, 'A', "Hello").
4. Constants: Immutable values declared using the const keyword.
5. Operators: Symbols used for performing operations (e.g., +, -, *, /).
6. Punctuation or Symbols: Special characters used for syntactic structure (e.g., {, }, ;, ,).

Example:

int age = 25; // Example of tokens in a C++ program
// Tokens: int (keyword), age (identifier), = (operator), 25 (literal), ; (punctuation)

By understanding tokens, programmers can better analyze and structure their code.

6) Define ‘std’

In C++, std is the default namespace that contains all the standard functions, objects, and definitions provided by the C++ Standard Library. The term std is short for “standard.”

Key Points:

• It organizes code to prevent name conflicts.
• Commonly used features like cout, cin, string, and many algorithms are part of the std namespace.

Example Usage:

#include <iostream>
using namespace std; // This allows direct access to std components

int main() {
    cout << "Hello, World!" << endl; // `cout` is part of `std`
    return 0;
}

Alternatively, without using namespace std:

#include <iostream>

int main() {
    std::cout << "Hello, World!" << std::endl; // Explicitly use std
    return 0;
}

Benefits:

• Helps in avoiding conflicts between user-defined names and library names.
• Provides a structured way to use standard library features.

This is a common topic in C++ interview questions.

7) What are the C++ access specifiers?

Access specifiers in C++ define the visibility of class members (functions and variables).

1. Private: Accessible only within the same class.
2. Public: Accessible from anywhere.
3. Protected: Accessible within the same class and its derived (child) classes.

These access specifiers play a crucial role in encapsulation and are often asked in C++ interview questions.

8) What is the difference between new() and malloc()?

• new() is an operator, while malloc() is a function.
• With new(), you don’t need to use sizeof(), whereas with malloc(), you must.
• new() initializes the memory to 0, but malloc() allocates memory with random values.
• The new() operator allocates memory and calls the constructor for initialization, while malloc() allocates memory but does not call the constructor.
• new() is generally faster than malloc() because an operator is faster than a function.

These differences are important and often come up in C++ interview questions.

9) Define friend function.

A friend function in C++ is a function that is not a member of a class but has access to the private and protected members of that class. It is declared using the friend keyword inside the class. A friend function can be a regular function, a member function of another class, or even a function from another class.

The key point is that a friend function can access all the private and protected data of the class to which it is a friend, which regular non-member functions cannot.

For example:

class MyClass {
private:
    int data;
public:
    MyClass() : data(10) {}
    friend void display(MyClass &obj);
};

void display(MyClass &obj) {
    cout << "Data: " << obj.data << endl;  // Accessing private member of MyClass
}

int main() {
    MyClass obj;
    display(obj);  // Friend function accessing private data
    return 0;
}

In this case, display is a friend function and can access the private member data of MyClass.

Friend functions are a common topic in C++ interview questions.

10) What is a virtual function?

A virtual function in C++ is a function that is declared within a base class and is redefined (overridden) in a derived class. The primary purpose of a virtual function is to allow dynamic polymorphism, which enables the correct function to be called for an object, regardless of the type of reference (or pointer) used for the function call.

When a function is declared as virtual in the base class, C++ ensures that the function call is resolved at runtime based on the type of the object pointed to or referenced, rather than the type of the pointer or reference.

This is particularly useful in cases of inheritance, where we have a base class and a derived class, and we want to call the function of the derived class even if we are using a pointer or reference of the base class.

Example:

#include<iostream>
using namespace std;

class Base {
public:
    virtual void show() {
        cout << "Base class show function" << endl;
    }
};

class Derived : public Base {
public:
    void show() override { // Overriding base class show function
        cout << "Derived class show function" << endl;
    }
};

int main() {
    Base *basePtr;
    Derived derivedObj;
    
    // Using base class pointer but pointing to derived class object
    basePtr = &derivedObj;
    
    // Virtual function ensures the call is resolved at runtime
    basePtr->show();  // Output: Derived class show function
    
    return 0;
}

In the above example, even though basePtr is a pointer to the base class, it calls the show() function of the derived class because of the virtual function mechanism.

Virtual functions are a fundamental concept in C++ interview questions.

11) What is a constructor?

A constructor is a special type of member function in C++ that is automatically called when an object of a class is created. Its primary purpose is to initialize the object’s data members and allocate any resources it may need. The constructor has the same name as the class and does not have a return type, not even void.

There are two types of constructors in C++:

1. Default Constructor: A constructor that takes no arguments. If no constructor is provided by the programmer, the compiler provides a default constructor.
2. Parameterized Constructor: A constructor that takes arguments to initialize an object with specific values when it is created.

Example:

#include<iostream>
using namespace std;

class Person {
public:
    string name;
    int age;

    // Default constructor
    Person() {
        name = "Unknown";
        age = 0;
    }

    // Parameterized constructor
    Person(string n, int a) {
        name = n;
        age = a;
    }

    void display() {
        cout << "Name: " << name << ", Age: " << age << endl;
    }
};

int main() {
    Person p1;  // Calls the default constructor
    Person p2("Alice", 25);  // Calls the parameterized constructor

    p1.display();  // Output: Name: Unknown, Age: 0
    p2.display();  // Output: Name: Alice, Age: 25

    return 0;
}

In this example, the default constructor initializes name to “Unknown” and age to 0, while the parameterized constructor allows the user to initialize the values when creating the object.

Constructors are important topics often covered in C++ interview questions.

12) Define namespace in C++.

A namespace in C++ is a container used to organize code into logical groups and prevent name conflicts. It allows you to group classes, functions, and variables under a name so that they can be easily identified and accessed without conflicting with other parts of the program.

Namespaces are particularly useful in large projects where many libraries or modules are being used. By using namespaces, you can avoid clashes between identifiers (such as variable or function names) that may be defined in different libraries.

Syntax:

namespace NamespaceName {
    // Variables, functions, classes, etc.
}

Example:

#include <iostream>
using namespace std;

namespace Math {
    int add(int a, int b) {
        return a + b;
    }

    int multiply(int a, int b) {
        return a * b;
    }
}

namespace Science {
    int add(int a, int b) {
        return a - b;  // Different logic for add in Science namespace
    }
}

int main() {
    int sum = Math::add(3, 4);  // Accessing Math namespace
    int difference = Science::add(10, 4);  // Accessing Science namespace

    cout << "Sum from Math: " << sum << endl;
    cout << "Difference from Science: " << difference << endl;

    return 0;
}

Output:

Sum from Math: 7
Difference from Science: 6

In this example, the Math and Science namespaces both define an add function, but they have different implementations. The namespace allows both functions to coexist without conflict. The syntax Math::add and Science::add helps in accessing the respective functions from the different namespaces.

Namespaces are crucial in avoiding naming conflicts in large C++ programs, making them a common topic in C++ interview questions.

13) Which programming language’s unsatisfactory performance led to the discovery of C++?

C++ was developed to address the limitations of the C programming language. While C was a powerful and efficient language for system-level programming, it lacked features that facilitated the development of large and complex applications. Specifically, C did not support object-oriented programming (OOP), which became increasingly important as software systems grew in size and complexity.

To overcome these shortcomings, Bjarne Stroustrup designed C++ by adding object-oriented features such as classes, inheritance, and polymorphism to the C language. This made C++ not only backward compatible with C but also more suitable for managing large codebases, improving software maintainability, and supporting the development of more modular and reusable code.

The main motivation behind the creation of C++ was to extend C to support more advanced programming paradigms, particularly object-oriented programming, while maintaining the efficiency and low-level capabilities of C.

C++ is an evolution of C, designed to address its limitations, and thus, C programming language’s unsatisfactory performance in handling complex applications led to the discovery of C++. This context is frequently explored in C++ interview questions.

Also Read: What Are Basic IT Questions and Answers 2025?