Top C++ Interview Questions and Answers for 2024

Top C++ Interview Questions and Answers for 2024

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Updated on Feb 8, 2023 23:39 IST

C++ is one of the most popular programming languages that is widely used by programmers around the world. In this article, we will discuss top 20 c++ questions that are asked in the interview rounds by the top companies.

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C++ is a popular object-oriented programming (OOP) language. Due to its reliability, speed, compatibility, and performance, it is widely used in the development of operating systems, applications, games, servers, and more. There is a high demand for C++ developers in the job market. If you are preparing for a C++ interview, this article will acquaint you with the types of questions you may encounter during your interview. For both freshers and experienced candidates, here are the most commonly asked C++ interview questions and answers.

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Top C++ Interview Questions and Answers for 2024

Q1. What is C++?

Ans. C++ is a powerful, all-purpose, case-sensitive, and free-form programming language. It was developed by Bjarne Stroustrup at Bell Labs. It is an extension of C and supports object-oriented, procedural, and generic programming. C++ has a wide range of applications. Uses cases of this programming language are operating systems, database software, banking applications, embedded systems, and more.

Q2. What are the features of C++?

Ans. The following are some of the features of C++:

  • Compiler-based language
  • Fast and powerful
  • Object-Oriented Programming (OOP) language
  • Extensible
  • Dynamic memory allocation
  • Multi-Dimensional language
  • Highly portable
  • Rich library

Q3. What are the differences between C and C++?

Ans. The differences between C and C++ are:

C C++
C language is a procedure-oriented programming language It is a partially object-oriented programming language
Developed by Dennis Ritchie between the years 1969 and 1973 Developed by Bjarne Stroustrup in 1979
Function-driven language Object-driven language
C uses a top-down approach It follows a bottom-up approach
C does not support function or operator overloading C++ supports function and function overloading
Uses stdio.h header file Uses the iostream.h header file
Does not support inline functions Supports inline functions
It does not support information hiding Data is hidden by the Encapsulation

Q4. What are access modifiers in C++?

Ans. We use access modifiers to define how to access the class members outside the class. It defines how functions and variables can be accessed outside the class scope.

C++ language has three types of access modifiers:

  • Private – The functions and variables can be accessed only within the same class.
  • Public – The functions and variables can be accessed from anywhere.
  • Protected – Functions and variables cannot be accessed outside the class except a child class.

Q5. How to export a function from a DLL?

Ans. There are two ways to export a function from a DLL:

  1. Use the DLL’s type library
  2. Take a reference to the function from the DLL instance

Also Read: Top C Programming Interview Questions

Q6. What is Templates in C++?

Ans. Templates in C++ is a blueprint to create a generic class or a function. WE use it to pass data types as parameters. Using templates, we can create a single function or single class which can work with different data types.

There are two types of Templates in C++

  • Function template
  • Class templates

For Example


 
template <typename T>
int fun (T x,T y)
{
return (x+y);
}
int main(){
cout<<fun<int>(11,22);
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Q7. What is STL?

Ans. STL (Standard Template Library) is a library of C++. It is a collection of C++ template classes that provide generic programming data structures and functions such as lists, arrays, and stacks. The components of STL are heavily parameterized.

STL comprises four components:

  1. Algorithms
  2. Containers
  3. Functions
  4. Iterators
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Q8. What is Encapsulation in C++?

Ans.: Encapsulation is the process of wrapping together the data and the functions that use them in a single unit. Since it bundles the related data and functions together, this makes the code cleaner and easy to read.

There are three types of Encapsulation in C++:

  • Member Variable Encapsulation – all the data members are declared as private.
  • Function Encapsulation – some member functions are declared as private.
  • Class Encapsulation – all a class is declared as private.

Program to illustrate Encapsulation


 
class Rectangle {
Public:
int length;
int breadth;
int getArea() {
return length * breadth;
}
};
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In the above program, the data members are length and breadth and the function is getArea(). A declared class wraps both data members and functions.

Also Read: Learn Data Types in C Programming

Q9. Define Abstraction in C++.

Ans. An abstraction in C++ is the technique of displaying only essential information and hiding the internal implementations and background details from the user. We can take a real-life example of a Television. We can control its various functions such as on, off, volume, etc., with just a click of a button on the remote control. But the internal process followed to perform the functions is not displayed.

We can implement Abstraction In C++ in two ways:

  • Classes and access specifiers
  • Header files implementation

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Q10. What is Inheritance in C++?

Ans. Inheritance is a process that enables classes to inherit the properties and behavior from other classes. Inheritance allows you to modify, reuse, and extend the attributes and behaviors which we define in the other class.

  • Derived class or Sub class – The class which inherits the properties from another class is called the derived class. It is the specialized class for the base class.
  • Base class or Super class – The class whose properties are inherited is called the base class.

Q11. Can you overload a destructor in C++?

Ans. No, we cannot overload a destructor in C++ because there is only one destructor per class.

Must Read: What is Coding: Difference Between Coding And Programming

Q12. What is a Block scope variable?

Ans. A Block scope variable is specified within a block of code. W can declare it anywhere within the block of code, such as an if statement or a for loop statement.

Q13. What is a virtual function?

Ans. Virtual function in C++ is a member function in the base class that we redefine in a derived class. We declare the virtual function using the virtual keyword. The virtual functions ensure that the correct function is called for an object, irrespective of the expression used to make the call.

Q14. How to copy and paste in turbo C++?

Ans. Top copy in turbo C++: Press Ctrl + Insert

To copy in turbo C++: Press Shift + Insert

Q15. Explain the difference between equal to (==) and assignment operator(=).

Ans. The equal to or == operator is used to determine if two values are equal. If the values are equal, it will return true. If they are not equal, it will return false. On the other hand, the we use assignment or = operator to assign the value on the right to the variable present on the left. 

Q16. What is the size of the int data type in C++?

Ans. The size of the int data type in C++ is 4 bytes. 

Q17. Can we overload a destructor of a class in C++ programming?

Ans. No, destructor overloading is not possible in C++ programming. 

Q18. How to find the length of an array in C++?

Ans. We use the sizeof() function to find the length of an array in C++:


 
#include <iostream>
using namespace std;
int main() {
int arr[] = {5,10,15,20,25,30};
int arrSize = sizeof(arr)/sizeof(arr[0]);
cout << "Size of the array is: " << arrSize;
return 0;
}
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Output

Size of the array is: 6

Also Read: Top Universities Offering Free Online Programming Courses

Q19. Write a program to reverse a string in C++?

Ans. Below is the code to reverse a string in C++:


 
#include <iostream>
using namespace std;
int main()
{
int i,fact=1,number;
cout<<"Enter number to find its factorial: ";
cin>>number;
for(i=1;i<=number;i++){
fact=fact*i;
}
cout<<"Factorial of given number is: "<<fact<<endl;
return 0;
}
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Q20. Write a program to find the factorial of a number.

Ans. Below is the program to find the factorial of a number:


 
#include <iostream>
using namespace std;
int main()
{
int i,fact=1,number;
cout<<"Enter number to find its factorial: ";
cin>>number;
for(i=1;i<=number;i++){
fact=fact*i;
}
cout<<"Factorial of given number is: "<<fact<<endl;
return 0;
}
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Output

Enter number to find its factorial: 5 
Factorial of given number is: 120

Conclusion

This sums up the list of frequently asked C++ interview questions. We hope this blog gave you a solid understanding of the basic and advanced concepts of programming in C++. This list of important C++ questions will help you prepare better and make you feel more confident in your next C++ job interview.

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