C++ Interview Questions and Answers

Top 50 Cpp Interview Questions and Answers

Looking to ace your C++ interview? PrepInsta offers an extensive collection of frequently asked C++ interview questions and answers. Whether you’re a fresher or an experienced candidate, you’ll find up-to-date insights on C++ concepts. Prepare effectively for your interview with PrepInsta’s comprehensive resources.

C++ in a nutshell:


C++ is a clever language that can do a lot of things. It’s like having a toolbox full of tools that can build almost anything you want on a computer. It’s easy to use, but it’s also quite powerful, like a superhero in the coding world.

Where C++ is used?

  1. Systems Programming: Operating systems, drivers.
  2. Game Development: Video games, game engines.
  3. High Performance: Simulations, scientific computing.
  4. Embedded Systems: IoT, microcontrollers.
  5. Graphics: Graphics libraries, computer vision.
  6. Financial Software: Trading, risk analysis.
  7. Networking: Protocols, communication systems.
  8. Real-Time: Robotics, industrial automation.
  9. Library Development: Reusable components.
  10. Cross-Platform: Write once, run on different OS.
  11. Open Source: Many projects.
  12. HPC: Scientific simulations, clusters.

C++ excels where performance, control, and efficiency are vital.

Getting Ready for Interviews

Imagine you’re getting ready for a big adventure—like a treasure hunt. Getting ready for a job interview involving C++ is a bit like that. Here’s how you can prepare:

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C++ Interview Questions and Answers For Freshers

Ques 1: What is C++?

Ans.C++ is a general-purpose programming language that extends the capabilities of the C programming language. It supports both high-level features for easier programming and low-level features for direct hardware manipulation. C++ is widely used for developing software applications, games, system software, and more due to its performance, flexibility, and object-oriented features.


Ques 2: What are Class and Object? Explain with example.

Ans. In C++, a class is a blueprint defining attributes (data members) and behaviors (methods) of objects. An object is an instance of a class, embodying its attributes and capable of performing its actions. For instance:




In this example, the Smartphone class defines the structure and behavior of a smartphone, and the myPhone object is a specific instance of that class, representing a smartphone with its own attributes and capabilities. Just as in programming, classes and objects help categorize and represent entities with shared characteristics and actions.

Ques 3: Difference between C and C++.
Aspect C C++
Programming Paradigm Procedural
Object-Oriented Data Hiding and Encapsulation : Data is not hidden; No encapsulation Encapsulation ensures controlled access to data; Data hiding supported
Relationship: Subset of C++ C++ extends C, adding OOP features
Standard Libraries: Not supported Function overloading and operator overloading are supported
Namespace: Not present Namespaces introduced to prevent naming collisions
Functions Inside Structures Functions cannot be defined inside structures
Member functions (methods) can be defined within classes
Memory Management Memory managed using `calloc()`, `malloc()`,` free()` `new` operator for memory allocation, `delete` operator for `deallocation`
Ques 4: Explain Operators and with example?


Operators in programming are symbols that define actions on operands. They’re vital for arithmetic, comparisons, logic, and more. Here’s a quick overview of key operator types in C++:

Arithmetic Operators:+ – * / %
Comparison Operators:== != > < >= <=
Logical Operators:&& || !
Assignment Operators:= += -= *= /= %=

Increment/Decrement Operators:

++ —

Bitwise Operators:& | ^ ~
Ques 5: What is Virtual functions?

Ans. Virtual function is a member function of a base class that can be overridden in a derived class. When a function is declared as “virtual,” it enables dynamic polymorphism, which means that the appropriate function to be called is determined at runtime based on the actual object’s type. This allows for more flexible and extensible code, particularly when dealing with inheritance and class hierarchies.


Ques 6: Compare Overloading Function Overriding Function.
Aspect Function Overloading Function Overriding
Definition Multiple functions with same name but different parameter lists within the same class or namespace. Providing a new implementation of a virtual function in a derived class that overrides the base class’s version.
Parameters Functions have different parameter lists (type and/or number of parameters). Functions must have the same name, return type, and parameters (signature) as the base class’s virtual function.
Access: Can be used to provide multiple variations of a function within the same scope. Used to customize the behavior of a function inherited from the base class.
Keyword Usage No special keyword is required.
The `virtual` keyword is used in the base class for functions intended to be overridden. The override keyword is used in the derived class to ensure proper overriding.
Example cpp void print(int num); void print(double num); cpp class Shape { public: virtual void draw(); }; class Circle : public Shape { public: void draw() override; };
Ques 7: Explain the concept of Polymorphism in c++?

Ans. Virtual function is a member function of a base class that can be overridden in a derived class. When a function is declared as “virtual,” it enables dynamic polymorphism, which means that the appropriate function to be called is determined at runtime based on the actual object’s type. This allows for more flexible and extensible code, particularly when dealing with inheritance and class hierarchies.

For Example:

Imagine a “Shape” class with a “draw” method. Different shapes like “Circle,” “Rectangle,” and “Triangle” are subclasses of “Shape.” Even though each shape’s “draw” method is different, they’re all accessed and used in the same way. This is polymorphism in action – different shapes sharing a common interface (“draw”) but behaving differently based on their individual implementations.

There are Two Types of Polymorphism.

  • Compile Time
  • Run Time


Ques 8: Explain function overloading.
Ans.Function overloading refers to defining multiple functions with the same name but different parameter types or counts. This allows you to use the same function name for operations that conceptually do the same thing but with different inputs. Example:
class #include 

class Calculator {
    int add(int a, int b) {
        return a + b;

    double add(double a, double b) {
        return a + b;

int main() {
    Calculator calc;
    std::cout << calc.add(5, 10) << std::endl;        // Calls int add(int a, int b)
    std::cout << calc.add(3.14, 2.71) << std::endl;   // Calls double add(double a, double b)
    return 0;
In this example, the Calculator class has two add methods with different parameter types (int and double). Depending on the parameter types passed when calling the add function, the appropriate version of the function is invoked. This is function overloading in action.
Ques 9: What is the significance of the const keyword in C++?

Ans. The const keyword in C++ is used to indicate that a variable or function won’t be modified after its initialization. It’s crucial for maintaining code correctness and preventing accidental changes to values. It’s used with variables, function parameters, member functions, and pointers to ensure code quality and reliability.

Ques 10: Explain the importance of the main() function in a C++ program.

Ans. The main() function is vital in a C++ program as it’s where execution begins. When the program is run, the operating system calls main(). It’s responsible for organizing the program’s actions, user interactions, and function calls. You structure the program’s logic within main(), and it often utilizes functions you’ve defined. Additionally, main() can return an integer value, typically 0 for success and non-zero for errors. In essence, it’s the entry point and central control hub of a C++ program.

  • Starting Point: main() is the entry point of a C++ program, where execution begins upon running the program.
  • Program Logic: It holds the high-level logic, orchestrating tasks, operations, and interactions.
  • User Interaction: main often uses input/output functions (cin, cout)to communicate with users.
  • Function Calls: It coordinates the execution of functions defined in the program.
  • Return Value: main() can provide a return value to the operating system, indicating success or errors.
  • Control Hub: It’s the core of the program’s structure and execution, directing its flow and actions.

C++ Interview Questions With Answers

Ques 11: What is a constructor and a destructor? How are they different?

Ans. A constructor is a special function in a class that gets automatically called when an object of that class is created. It’s used to initialize the object’s attributes and set up any required resources.

A destructor, on the other hand, is another special function that’s automatically called when an object goes out of scope or is explicitly deleted. Its purpose is to clean up resources that the object acquired during its lifetime.

In short, constructors initialize objects, while destructors clean up objects before they are removed from memory.


  • Initialize objects upon creation.
  • Automatically invoked during object instantiation.
  • Same name as the class, no return type.
  • Can be overloaded with different parameter sets.
  • Set initial values and allocate resources.


  • Clean up resources before destruction.
  • Automatically invoked when object goes out of scope or is deleted.
  • Named with ~ followed by class name, no parameters.
  • Release allocated resources and perform final actions.
Ques 12: What is the difference between malloc and new in C++?



  • malloc is a C standard library function available in.
  • It doesn’t have any idea about the type of memory it’s allocating; it deals with bytes.
  • Since it doesn’t know about types, it doesn’t invoke constructors or initializations.
  • It returns a raw pointer of type void*, which requires explicit casting to the desired pointer type.
  • It doesn’t handle exceptions natively; if allocation fails, it returns a nullptr.


  • new is a C++ operator that handles dynamic memory allocation.
  • It’s more integrated with C++ features and knows the type it’s allocating memory for.
  • It invokes constructors for objects being created in the allocated memory.
  • It returns a pointer to the specific type being allocated, so casting is not needed.
  • If memory allocation fails, it throws a std::bad_alloc exception.
Ques 13: Explain Inheritance


Inheritance is a core concept in object-oriented programming where a new class can inherit properties and behaviors from an existing class. It promotes code reuse and hierarchy creation:

  • Code Reuse: Avoids duplication by inheriting code from a base class.
  • Single & Multiple Inheritance: Inherits from one or more classes.
  • Method Overriding: Customizes inherited methods in derived classes.
  • Polymorphism: Allows treating different classes as one type.
  • Access Control: Manages visibility of inherited members.
Ques 14: Explain friend class and friend function.


Friend Function: A friend function is a non-member function that is granted access to a class’s private and protected members.

Friend Class: A friend class is a class that is allowed to access the private and protected members of another class.


using namespace std;
class MyClass {
    int secretValue;
    // Declare friend function and class
    friend void friendFunction(MyClass& obj);
    friend class FriendClass;

    MyClass(int value) : secretValue(value) {}

void friendFunction(MyClass& obj) {
    cout << "Accessing private member through friend function: " << obj.secretValue << std::endl;

class FriendClass {
    void accessPrivateMember(MyClass& obj) {
        cout << "Accessing private member through friend class: " << obj.secretValue << std::endl;

int main() {
    MyClass obj(42);

    FriendClass friendObj;

    return 0;
Ques 15: Explain inline function and provide an example of how it can be used in C++.


An inline function in C++ is a function whose code is inserted directly into the calling code, reducing the overhead of function calls. It’s declared using the inline keyword before the function declaration. Here’s a short example:

 #include <iostream>

// Inline function declaration
inline int multiply(int a, int b) {
    return a * b;

int main() {
    int result = multiply(3, 4);
    std::cout << "Result: " << result << std::endl;
    return 0;

C++ Interview Questions and Answers For Professionals

Ques 16: What is STL?


STL stands for “Standard Template Library” in C++. It’s a collection of template classes and functions that provide common data structures (containers) like vectors, lists, and maps, as well as algorithms (sorting, searching) and iterators for efficient data manipulation. The STL enhances code reusability and productivity by offering a standardized set of tools for various programming tasks.

Ques 17 :Define namespace in C++?


namespace is a declarative region that provides a scope to the identifiers (the names of types, functions, variables, etc) inside it. Namespaces are used to organize code into logical groups and to prevent name collisions that can occur especially when your codebase includes multiple libraries.

The namespace is a logical division of the code that is designed to stop the naming conflict.
The namespace defines the scope where the identifiers such as variables, class, functions are declared.
C++ consists of a standard namespace, i.e., std which contains inbuilt classes and functions. So, by using the statement “using namespace std;” includes the namespace “std” in our program.
The main purpose of using namespace in C++ is to remove ambiguity. Ambiguity occurs when a different task occurs with the same name.

For example: if two functions exist with the same name such as add(). To prevent this ambiguity, the namespace is used. Functions are declared in different namespaces.

Syntax of the namespace:

namespace namespace_name
//body of namespace;
Ques 18: Explain what is C++ exceptional handling?


One of the advantages of C++ over C is Exception Handling. Exceptions are run-time anomalies or abnormal conditions that a program encounters during its execution.

The problem that arises during the execution of a program is referred to as exceptional handling. The exceptional handling in C++ is done by three keywords.

  • try: represents a block of code that can throw an exception.
  • catch: represents a block of code that is executed when a particular exception is thrown.
  • throw: Used to throw an exception. Also used to list the exceptions that a function throws, but doesn’t handle itself.
Ques 19: Define Pointers?


  • Pointes is a special type of variables that are used to store the memory address of the other variables.
  • Pointers are declared normally as other variables with a difference of * that is present in front of the pointer identifier.
  • There are two operators that are used with the pointers one is ‘&’ and another one is ‘*’. & is known as the address of operator and * is known as dereferencing operator, both are prefix unary operators.
Ques 20: What is the output of the following code:


#include <iostream>

class A {
    A() {}
    ~A() {
        throw 42;

int main(int argc, const char * argv[]) {
    try {
        A a;
        throw 32;
    } catch(int a) {
        std::cout << a;


This program will terminate abnormally. throw 32 will start unwinding the stack and destroy class A.

The class A destructor will throw another exception during the exception handling, which will cause the program to crash.

Ques 21: What is references and pointers?


Pointers: A pointer is a variable that holds the memory address of another variable. A pointer needs to be dereferenced with the * operator to access the memory location it points to.

References: A reference variable is an alias, that is, another name for an already existing variable. A reference, like a pointer, is also implemented by storing the address of an object.
A reference can be thought of as a constant pointer (not to be confused with a pointer to a constant value!) with automatic indirection, i.e the compiler will apply the * operator for you.

  • References are less powerful than pointers:
    1) Once a reference is created, it cannot be later made to reference another object; it cannot be reseated. This is often done with pointers.
    2) References cannot be NULL. Pointers are often made NULL to indicate that they are not pointing to any valid thing.
    3) A reference must be initialized when declared. There is no such restriction with pointers
  • References are safer and easier to use:
    1) Safer: Since references must be initialized, wild references like wild pointers are unlikely to exist. It is still possible to have references that don’t refer to a valid location (See questions 5 and 6 in the below exercise )
    2) Easier to use: References don’t need dereferencing operator to access the value. They can be used like normal variables. ‘&’ operator is needed only at the time of declaration. Also, members of an object reference can be accessed with dot operator (‘.’), unlike pointers where arrow operator (->) is needed to access members.
Ques 22: What is equal to (==) and Assignment  Operator (=)?


In C++, equal to (==) and assignment operator (=) are two completely different operators.

  • The assignment operator (=) is used to assign a value to a variable. Hence, we can have a complex assignment operation inside the equality relational operator for evaluation.
  • Equal to (==) is an equality relational operator that evaluates two expressions to see if they are equal and returns true if they are equal and false if they are not.
Ques 23:  Which operations are permitted on pointers?


In C++ programming the following operations are allowed to perform on pointers:
Incrementing or decrementing a pointer: Incrementing a pointer means that we can increment the pointer by the size of a data type to which it points.

There are two types of increment/decrement pointers:

  1. Pre-increment/decrement pointer: The pre-increment/decrement operator increments the operand by 1, and the value of the expression becomes the resulting value of the incremented/decremented. Suppose ptr is a pointer then pre-increment/decrement pointer is represented as ++ptr.
  2. Post-increment/decrement pointer: The post-increment/decrement operator increments the operand by 1, but the value of the expression will be the value of the operand prior to the incremented/decremented value of the operand. Suppose ptr is a pointer then post-increment/decrement pointer is represented as ptr++.
Ques 24: Mention what are the decision-making statements in C++?
Ans. The major decision making statements in C++ are
  • if statement
  • switch statement
  • conditional operator
For example, we want to implement if condition in C++
int main ( )
  int, x, y;
  X= 10;
  Y= 5;
  if (x > y)
    Cout << "x is greater than y";

Cpp Interview Questions and Answers

Ques 25: What is Between Global Variables And Static Variables?


Global variables: Global variables are variables that are defined outside the function. The scope of global variables begins at the point where they are defined and lasts till the end of the file/program. They have external linkage, which means that in other source files, the same name refers to the same location in memory. The scope of the global variables remains throughout the program also the life span of these variables is throughout the program.

Static variables: Static variables are private to the source file where they are defined and do not conflict with other variables in other source files which would have the same name. The scope of the variable describes whether the variable is accessible at a certain point in the program or not.

Ques 26: How many times will this loop execute? Explain your answer.


unsigned char half_limit = 150;

for (unsigned char i = 0; i < 2 * half_limit; ++i)
    // do something;


This code will result in an infinite loop.

Here’s why:

The expression 2 * half_limit will get promoted to an int (based on C++ conversion rules) and will have a value of 300. However, since i is an unsigned char, it is represented by an 8-bit value which, after reaching 255, will overflow (so it will go back to 0) and the loop will therefore go on forever.

Ques 27: What is the role of protected access specifier?


A class member is accessible in the inherited class if the class member is protected. However, outside both the private and protected members are not accessible.

Ques 28: Distinguish between shallow copy and deep copy.


Shallow copy performs bit-by-bit memory dumping from one object to another. Deep copy is the process of copying an object field by field from one object to another. The copy function Object() { [native code] } and the overloading assignment operator are used to achieve deep copy.

Ques 29: Explain what is C++ exceptional handling?


The following are storage classes supported in C++ :

  • auto
  • static
  • extern
  • register
  • mutable
Ques 30: What is the role of a mutable storage class specifier?


The member variable of a constant class object may be used by declaring it with the mutable storage class specifier. Just applies to the class’s non-static and non-constant member variables. doesn’t handle itself.

Ques 31: What is a class template?


A template class is a prototype class. A template class can be described using the keyword template.

Ques 32: What Is The Memory Structure Of An Object?


Usually C++ objects are made by concatenating member variables.

For example;

class Test


int I;

float j;


It is represented by an int followed by a float.

class TestSub: public Test


int k;


The above class is represented by Test and then an int(for int k). So finally it will be int, float, and int.

In addition to this, each object will have the vptr(virtual pointer) if the class has the virtual function, usually as the first element in a class.

Ques 33: Define Encapsulation in C++?


The process of encapsulating data and functions in a class is called encapsulation. For security purposes, it is used to prevent direct access to data. This is accomplished by using class functions.

For example, the net banking facility for customers allows only the approved person with the proper login id and password to access the information in the bank data source, and only for his or her part of the information.

Ques 34: What Is The Difference Between Exit And Abort?
  • Exit performs a graceful process termination by invoking the destructors for all constructed objects, while abort does not.
  • Exiting the local The destructors of the calling functions and its callers’ variables will not be called.
Ques 35:  Write C++ code to create an array of objects using a new keyword and delete these objects. Also, proof that all the objects are deleted properly.


C++ not only preserves all elements of the C language, but it also simplifies memory management and introduces many new features, such as:

We know that when we generate a class object dynamically from heap memory with the new keyword, we must specifically delete it after we are finished with its operations to prevent memory leaks in C++ programs.

As an example, consider the class Pen below.

class Pen {
      Pen() { 
         cout << "Constructor..." <<endl; 
      ~Pen() { 
         cout << "Destructor...!" <<endl; 
	  void write(){
		  cout << "Writing...!" <<endl; 

Below is an example, of how we create an object of the class Pen dynamically and delete it after we are done with operations.

int main()
	//create an object dynamically
   Pen* pen = new Pen();
   delete pen;//de-allocate the memory
   return 0;

How to create an array of objects of a class in C?

Let’s see how we create an array of objects in the below C++ program example. In this example, we will create an array of 3 objects, perform operations and delete a dynamic array of pointers properly.

int main()
	//create an array of objects
   Pen* pen = new Pen[3];

   delete [] pen;//de-allocate array of objects

   return 0;



Proof of proper deletion of an array of objects in C++

First, note that if we create an object of a class and delete the object then class constructor and destructor will be called respectively.

In the above example, we have created an array of 3 objects and deleted it using statement delete [] pen; if we look at the output the class constructor and destructor were called 3 times each. means, we have deleted objects properly.

Now, If we delete the object using the statement “delete pen” ( This is a general mistake a programmer makes) then the destructor will be called only once, and for the rest 2 objects destructor will not be called and the program will crash. and this will prove that objects are not deleted properly.

Let’s see the output if we use the statement “delete pen”

int main()
	//create an array of objects
   Pen* pen = new Pen[3];

   //this is not a prper way to delete
   //array of objects
   delete pen;

   return 0;



and then the program will crash at run time.


In C++, a single object of a class created dynamically is deleted using the statement “delete pointer” and an array of objects are deleted using the statement “delete [ ] pointer”.

Ques 36: How many ways are there to initialize an int with a Constant?


There are two ways:

  • The first format uses traditional C notation.
    int result = 10;
  • The second format uses the constructor notation.
    int result (10);
Ques 37: Explain The Is-a And Has-a Class Relationships. How Would You Implement Each In A Class Design?


A specialized class “is” a specialization of another class and therefore shares an IS-A relationship with it. An ISA person who works for the business. Inheritance is the only way to implement this partnership. The word “employee” comes from the word “person.” A class can contain an instance of another class. Employees, for example, “have” salaries, because the Employee class has a HAS-A relationship with the Wage class. The best way to enforce this relationship is to embed a Salary class object in the Employee class.

Ques 38: Draw a comparison between C++ and Java
Feature C++ Java
Syntax and Language Paradigm C++ is a multi-paradigm language. It supports both procedural and object-oriented programming (OOP) paradigms. Additionally, it allows low-level memory manipulation through pointers. Java is primarily an object-oriented language. It enforces strong OOP principles, and its syntax is simpler and more consistent than C++. It lacks features like pointers, making it safer in terms of memory management.
Memory Management C++ offers manual memory management through pointers and explicit memory allocation/deallocation using new and delete. This level of control can lead to memory leaks and segmentation faults if not used correctly. Java provides automatic memory management through the Java Virtual Machine (JVM) and a garbage collector. Developers do not have to manually allocate or deallocate memory, reducing the risk of memory-related errors.
Platform Independence C++ code must be recompiled for each target platform, making it platform-dependent by default. Java follows the “Write Once, Run Anywhere” principle. It compiles code into platform-independent bytecode, which runs on any device with a compatible JVM.
Performance C++ is often considered faster and more efficient for certain tasks because it allows for low-level memory manipulation and direct hardware access.
Java is generally slower than C++ but offers good performance for most applications. It has improved over time with Just-In-Time (JIT) compilation and runtime optimizations.
Community and Ecosystem C++ has a long history and a mature ecosystem with numerous libraries and tools. Java also has a robust ecosystem and is widely used in enterprise software development and Android app development.

C++ Coding Questions and Answers

Ques 39:  When there are a Global variable and Local variable with the same name, how will you access the global variable?


When two variables have the same name but different scopes, for example, one is a local variable and the other is a global variable, the compiler would favor the local variable.

We use a “scope resolution operator (::)” to get access to the global variable. We can get the value of the global variable with this operator.


int x= 10;
int main()
int x= 2;
cout<<”Global Variable x = “<<::x;
cout<<”\nlocal Variable x= “<<x;


Global Variable x = 10
local Variable x= 2

Ques 40: Why do we need the Friend class and function?


It’s often necessary to grant specific class access to a class’s private or protected members. A friend class is a solution since it can access both protected and private members of the class in which it is declared as a friend. A friend feature, like the friend class, has access to private and safe class members.

Friendship is not something you inherit.

  • Friendship is not reciprocal, because if one class is a friend of another, such as NotAFriend, it does not immediately become a friend of the Friend class.
  • The total number of friend classes and friend functions in a program should be restricted because too many of them will degrade the principle of encapsulation of separate classes, which is an intrinsic and desirable quality of object-oriented programming.
Ques 41: What does the term “copy constructor” mean?
Ans. A copy constructor is like a special function in a class that helps create a new object by copying the values from another object of the same kind.
class A{
  int x,y;
  A(int x, int y){

 int main(){
   A a1(2,3);
   A a2=a1;     //default copy constructor is called
   return 0;
You have the option to make your own copy constructor. If you don’t, the system will automatically use a default one.
Ques 42: What are void pointers?


A void pointer, often denoted as void*, is a special type of pointer in programming that can point to any data type. It’s like a universal pointer that doesn’t have a fixed data type. You can use it to point to different types of data, but you need to be careful when you want to access or use the data it points to because the compiler doesn’t know the actual data type.

#include <iostream>

int main() {
    int num = 10;
    float decimal = 3.14;
    char letter = 'A';

    void* ptr;

    // Point the void pointer to different data types
    ptr = #
    std::cout << "Integer value: " << *static_cast<int*>(ptr) << std::endl;

    ptr = &decimal;
    std::cout << "Float value: " << *static_cast<float*>(ptr) << std::endl;

    ptr = &letter;
    std::cout << "Character value: " << *static_cast<char*>(ptr) << std::endl;

    return 0;

In this example, we still use a `void*` pointer to point to different data types and cast it using `static_cast` when accessing the data. This code achieves the same result as the previous C example but with a more concise C++ syntax.

Ques 43: What is an abstraction in C++?


In C++, abstraction is a concept that involves simplifying complex systems by hiding unnecessary details. It lets you create user-defined data types (classes) to represent real-world entities, focusing on what they do while hiding how they work. This is done by encapsulating data and providing controlled access, promoting code organization and reusability.

Ques 44: What is operator overloading in C++? Provide an example.


Operator overloading in C++ allows you to define how existing operators work with user-defined data types (classes and objects). It enables you to create custom behavior for operators when applied to objects of your classes.

Here’s a simple example of operator overloading using the + operator for a custom Complex class representing complex numbers:


class Complex {
    double real;
    double imaginary;

        Complex() : real(0.0), imaginary(0.0) {}

        Complex(double r, double i) : real(r), imaginary(i) {}

        Complex operator+(const Complex& other) {
        Complex result;
        result.real = real + other.real;
        result.imaginary = imaginary + other.imaginary;
        return result;

int main() {
    Complex num1(2.0, 3.0);
    Complex num2(1.5, 2.5);

    Complex sum = num1 + num2;

    std::cout << "Sum: " << sum.real << " + " << sum.imaginary << "i" << std::endl;

    return 0;

In this example, operator overloading is used to redefine the + operator for a custom Complex class to perform complex number addition.

Ques 45:  Explain the concept of static and dynamic binding in C++.

Static Binding (Compile-time Binding):

  • Decided at compile time.
  • Based on the declared type.
  • Used for non-virtual functions.
  • Faster but less flexible.

Dynamic Binding (Runtime Binding):

  • Decided at runtime.
  • Based on the actual (dynamic) type.
  • Used with virtual functions.
  • Allows polymorphism but slower due to runtime lookup.
Ques 46:  What is the diamond problem in C++? How is it resolved using virtual inheritance?


The diamond problem in C++ is an issue that arises in multiple inheritance when a class inherits from two or more classes that have a common base class. This results in ambiguity when trying to access members of the common base class through the derived class.

It is resolved using virtual inheritance by making sure that there’s only one instance of the common base class shared among the derived classes. This eliminates ambiguity by ensuring that the common base class is not duplicated in the inheritance hierarchy. It’s achieved by declaring the common base class as a virtual base class when inheriting from it. This way, the common base class is inherited only once, and the diamond problem is resolved.

Ques 47: What is the “Big Three” in C++?


The “Big Three” in C++ refers to three essential member functions when managing dynamic memory and objects:

  1. Destructor: Cleans up resources when an object is destroyed.
  2. Copy Constructor: Creates a copy of an object.
  3. Copy Assignment Operator: Assigns the values of one object to another.

They are crucial for proper resource management in classes.

Ques 48: Explain the differences between `public`, `protected`, and `private` access specifiers in classes.


The differences between the `public`, `protected`, and `private` access specifiers in C++ classes:

Access SpecifierAccessibility within the ClassAccessibility in Derived ClassesAccessibility Outside the Class
protectedAccessibleAccessible (for derived classes)Not Accessible
PrivateAccessibleNot Accessible .Not Accessible

Public Access Specifier: Members declared as public are accessible from anywhere. They can be accessed within the class, by derived classes, and from outside the class.

Protected Access Specifier: Members declared as protected are accessible within the class and by derived classes. They are not directly accessible from outside the class unless accessed through a friend function or a public/protected member function of the class.

Private Access Specifier: Members declared as private are accessible only within the class. They are not accessible from derived classes or outside the class.

Ques 49: Explain the concept of RAII (Resource Acquisition Is Initialization) in C++.


RAII (Resource Acquisition Is Initialization) in C++ means tying resource management to the lifetime of an object. Resources are acquired in the object’s constructor and released in its destructor. It simplifies code, ensures automatic resource cleanup, and provides better exception safety.

Ques 50: How does the `volatile` keyword affect variable access in C++?


The `volatile` keyword in C++ tells the compiler not to optimize access to a variable, ensuring that reads and writes to it are always performed, which is useful for variables that can change unexpectedly, like in multithreaded or embedded systems.

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