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CPP Interview Questions

Last Updated on October 21, 2023 by Prepbytes

The world of software development is constantly evolving, and one of the programming languages that has stood the test of time is C++. Whether you’re a seasoned C++ developer or just starting out, interviews for C++ positions can be a challenging but rewarding experience. In this article, we will explore a comprehensive list of C++ interview questions that cover a wide range of topics. These questions are designed to assess your knowledge and problem-solving skills, from the basics of C++ syntax to advanced topics like memory management and object-oriented programming.

As you prepare for your C++ interviews, this resource will serve as a valuable guide, helping you sharpen your skills and gain confidence. We’ll cover questions that are frequently asked in technical interviews, along with detailed explanations and sample answers. By the end of this article, you’ll not only be better equipped to tackle C++ interviews but also have a deeper understanding of C++ programming concepts.

Commonly Asked CPP Interview Questions

Here are 30 C++ interview questions along with their answers:

1. What is C++?
C++ is a general-purpose, high-level programming language derived from C. It supports both procedural and object-oriented programming paradigms.

2. What is the difference between C and C++?
C++ includes object-oriented features like classes and objects, whereas C is a procedural language. C++ also provides better type safety and supports function overloading, whereas C does not.

3. Explain the concept of Object-Oriented Programming (OOP) in C++.
OOP is a programming paradigm in which data and behaviors (functions) are encapsulated into objects. It promotes concepts like inheritance, polymorphism, and encapsulation.

4. What is a class in C++?
A class is a blueprint for creating objects. It defines the structure and behavior of objects.

5. What is an object in C++?
An object is an instance of a class. It represents a real-world entity and can be used to access the data and methods defined in the class.

6. Explain the difference between a class and an object.
A class is a blueprint or template, while an object is an instance of that class. Classes define the structure, and objects represent instances of that structure.

7. What is the constructor in C++?
A constructor is a special member function that gets called when an object of a class is created. It is used for initializing the object’s properties.

8. What is function overloading in C++?
Function overloading allows multiple functions in a class with the same name but different parameters. The correct function is called based on the arguments provided.

9. Explain the concept of inheritance in C++.
Inheritance allows a class to inherit properties and behaviors from another class. It promotes code reusability and the creation of a hierarchy of classes.

10. What is the difference between private, protected, and public access specifiers in C++ classes?
These access specifiers determine the visibility of class members:

  • private: Members are only accessible within the class.
  • protected: Members are accessible within the class and its derived classes.
  • public: Members are accessible from anywhere.

11. What is a destructor in C++?
A destructor is a special member function used to clean up resources when an object goes out of scope or is explicitly destroyed. It has the same name as the class with a tilde (~) prefix.

12. What is the difference between new and malloc() in C++?
new is an operator in C++ used for dynamic memory allocation and object creation, while malloc() is a library function in C used for dynamic memory allocation. new also calls the constructor for object initialization.

13. Explain RAII (Resource Acquisition Is Initialization) in C++.
RAII is a C++ programming technique where resource management (e.g., memory, file handles) is tied to the lifetime of an object. Resources are acquired in the constructor and released in the destructor.

14. What are smart pointers in C++?
Smart pointers (e.g., std::shared_ptr, std::unique_ptr) are C++ classes that manage the lifetime of dynamically allocated objects, automatically releasing memory when it’s no longer needed.

15. What is operator overloading in C++?
Operator overloading allows you to define custom behaviors for operators like +, -, *, etc., when applied to objects of user-defined classes.

16. Explain the const keyword in C++.
The const keyword is used to indicate that a variable or function parameter cannot be modified. It ensures that the value remains constant.

17. What is a reference in C++?
A reference is an alias or an alternative name for an existing variable. It allows you to manipulate the original variable indirectly.

18. What is the Standard Template Library (STL) in C++?
The STL is a collection of template classes and functions that provide common data structures (e.g., vectors, lists, maps) and algorithms (e.g., sorting, searching) in C++.

19. What is a template in C++?
A template is a feature that allows you to define generic classes and functions. It enables you to write code that works with different data types.

20. Explain the difference between vector and array in C++.
A vector is a dynamic array that can change in size at runtime, while an array has a fixed size determined at compile time.

21. What is polymorphism in C++?
Polymorphism allows objects of different classes to be treated as objects of a common base class. It enables function calls to be resolved at runtime (runtime polymorphism) using virtual functions.

22. What is a virtual function in C++?
A virtual function is a member function declared in a base class with the virtual keyword. It allows derived classes to override the function’s implementation.

23. What is a pure virtual function in C++?
A pure virtual function is a virtual function with no implementation in the base class. It is meant to be overridden by derived classes, and any class containing a pure virtual function is an abstract class.

24. How does exception handling work in C++?
C++ provides a mechanism for handling exceptions using try, catch, and throw keywords. try blocks contain code that might throw an exception, and catch blocks handle specific types of exceptions.

25. What is a namespace in C++?
A namespace is a way to organize code elements (e.g., classes, functions) into named scopes to prevent naming conflicts.

26. Explain the difference between nullptr and NULL in C++11 and later.
In C++11 and later, nullptr is a keyword that represents a null pointer, providing better type safety. NULL is an older macro defined as 0 or (void*)0 and is less type-safe.

27. What are lambda expressions in C++?
Lambda expressions allow you to define anonymous functions in C++. They are particularly useful in situations where you need a short, inline function.

28. How do you handle memory leaks in C++?
Memory leaks can be mitigated by using smart pointers, proper resource management, and adhering to the RAII principle. Additionally, tools like Valgrind can help detect and fix memory leaks.

29. What is the purpose of the volatile keyword in C++?
The volatile keyword is used to indicate that a variable can be changed by external factors, such as hardware or other threads. It prevents the compiler from optimizing access to that variable.

30. What is function template specialization in C++?
Function template specialization allows you to provide a custom implementation of a template function for a specific data type, overriding the generic template.

In the competitive world of software development, C++ remains a sought-after skill, and mastering it can open doors to exciting career opportunities. This article has provided you with a comprehensive list of C++ interview questions that encompass a wide range of topics, from the fundamentals of C++ to more advanced concepts.

As you prepare for your C++ interviews, remember that practice and understanding are key. Work through these questions, explore the explanations and sample answers, and, most importantly, continue learning and improving your C++ skills. Whether you’re aiming for a junior, mid-level, or senior C++ developer role, the knowledge and confidence you gain from this resource will undoubtedly be valuable in your job search.

Now, armed with this knowledge, go ahead and face your C++ interviews with confidence. Best of luck in your endeavors, and may your C++ journey be filled with exciting challenges and rewarding opportunities.

FAQ (Frequently Asked Questions) Related to CPP interview Questions

Here are some FAQs related to CPP interview Questions.

1. What types of C++ interview questions can I expect?
C++ interview questions can range from basic syntax and data structures to more complex topics like memory management, object-oriented programming, and design patterns. Expect questions related to pointers, templates, inheritance, polymorphism, and the Standard Template Library (STL).

2. How can I prepare for C++ interviews?
Preparation involves studying C++ concepts thoroughly, practicing coding problems, and reviewing common interview questions. This article provides a comprehensive list of questions to help you get started.

3. Are there any specific C++ features or topics I should focus on for interviews?
While it’s essential to have a strong foundation in C++ basics, be prepared to delve into memory management, smart pointers, multithreading, and design patterns. Understanding how to write efficient, bug-free code is crucial.

4. Should I memorize answers to these questions?
Memorizing answers is not recommended. Instead, focus on understanding the underlying concepts. Interviewers often appreciate candidates who can explain their thought process and adapt their knowledge to different scenarios.

5. How can I gain practical experience in C++ to complement my interview preparation?
Building real-world projects and contributing to open-source C++ projects can provide valuable practical experience. Additionally, practice coding problems on platforms like LeetCode, HackerRank, or Codeforces to enhance your problem-solving skills.

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