C++

General questions

1. What is the difference between a reference and a pointer?
2. Explain the difference between int x; int x(); and int x{};
3. assert(sizeof(int) != sizeof(long)); Is this statement always true?
4. What will the following line of code print out and why? unsigned int x = -1; std::cout << x;
5. Can you explain the difference between new and new[]? Is it possible to delete memory using delete[] allocated within the new operator?
6. What is the difference between new/malloc or delete/free?
7. What is the difference between stack and heap allocation?
8. What is the evaluation order of the function parameters in C++?
9. What is the construction order of global variables?
10. What is the forward declaration of classes? What is it used for?
11. What is the meaning of a const keyword and how can it be used? 
12. What is the meaning of a static keyword and how can it be used? 
13. What are the advantages of using friend classes?
14. What is an abstract class? What is the pure virtual function?
15. How do you create a virtual constructor and virtual destructor for a class? Why would you do it? 
16. What is a vtable and how does it work?
17. Initialization order of Bases and Members.
18. Is it possible to call a virtual function inside of a constructor/destructor?
19. What is a template and how is it used? 
20. What is specialization? How can it help to improve efficiency? 
21. struct Vector{ int* data; int size; }; Write copy constructor, operator= and destructor for the struct Vector.
22. What is an iterator? What iterator types do you know?
23. What is RAII?
24. When should you use std::unique_ptr vs. std::shared_ptr? 
25. How should runtime errors be handled in C++? What general approaches do you know?
26. What will happen if the exception will be thrown within a constructor?
27. C++ supports multiple inheritance. What is the "diamond problem" that can occur with multiple inheritance? Give an example.

Concurrency and multithreading questions

1. How to create a new thread and give it an execution function? Give an example of a simple function.
2. What two modes of execution of the thread function can you name?
3. What C++ features can we use to protect data between multiple threads?
4. How can we synchronize data between threads?
5. There is a Value data type that works in a single-threaded environment. Make changes so that it works as efficiently as possible in a multi-threaded environment.

class Value 
{ 
private:
     int m_value{};

public:
      Value (){}
      int getValue() const
      { 
          return m_value;
      }
      void updateValue(int value)
      { 
          m_value = value; 
      } 
}

6. There is an algorithm that is divided into 5 parts. They must be executed one by one in different threads, using the result of the previous step. How do you implement it?
7. What is the difference between using std::async and std::thread?
8. There is a thread that reads the data, and there is a thread that uses the received data. These threads run independently. How do you implement synchronization between these threads?
9. What does the co_yield function do?
10. Explain the difference between sleep_for and sleep_until functions.
11. Is it possible to find out how many threads are available for parallel work using C++ tools?
12. There are two mutexes. How do you securely acquire them?
13. You have a function that needs to be called once, no matter how many threads you have. How will you do it?
14. What is std::promises used for?
15. What is std::packaged_task used for?
16. What is std::future used for?
17. Is it possible to return an exception from a thread? If yes, please explain.
18. Does adding multithreading always improve the result?
19. Is there an alternative to a mutex in C++ to ensure data protection?
20. What can you tell about std::atomic?
21. What is a race condition in a multi-threaded application?
22. What are coroutines?
23. What is std::jthread? Can you explain the difference between std::jthread and std::thread?

Literature