1. Which version of C++ do you usually use? Tell us what improvements have been made to C++ in this version and what new features have been introduced? Answer: C++11 and C++14. Smart pointers and lock management wrapper classes (lock_guard, scoped_lock, etc.) representing RAII ideas are introduced. The basic idea is to automatically manage the acquisition and release of resources, that is, when constructing an object, automatically acquire memory or locks; when destructing an object, automatically release the memory or locks it manages. Follow-up question: In what situations is scoped_lock mainly used? Can you give an example? Answer: scoped_lock is mainly used to manage multiple mutexes at the same time to avoid deadlock. For example: There is a bank account type. Each of its objects must be assigned a lock, because bank accounts may involve multiple threads making deposits or withdrawals at the same time. At this time, for transfer transactions involving two accounts, scoped_lock must be used to manage the mutex of the two account objects, otherwise a deadlock state may occur. Supplement: New features of C++11 2. Do you understand C++ polymorphism and inheritance? Let’s briefly talk about how to implement polymorphism in C++. Answer: Inheritance is divided into public, private and protected. After a subclass object inherits a parent class, it may be possible to call parent class variables or functions based on different inheritance relationships. For example: under shared inheritance, subclasses can use functions shared by the parent class. As for polymorphism, generally speaking, C++ relies on function overloading and virtual functions. Among them, function overloading is static, and virtual function overriding is dynamic. Because polymorphism relies on virtual functions, it is necessary to determine which version of the function to call based on the actual memory pointer. 3. Do you understand C++ memory management? Let’s briefly talk about C++ memory management. Answer: I just mentioned that C++ memory management mainly relies on smart pointers. For example: shared_ptr can decide whether to release based on the number of references. When the number of references is 0, the memory it manages is automatically released. Unique_ptr automatically releases the memory it manages when it is destructed. Follow-up question: Tell me about the difference between new and malloc in C++ Answer: new returns a type pointer, while malloc returns a void * pointer, which requires the user to convert it to the required type. In addition, malloc needs to calculate the requested memory size when using it, while new uses the object constructor directly. 4. Are you familiar with C++ multi-thread programming? Let’s talk about the basic use of locks, condition variables and threads in C++ multi-threaded programming. Answer: We talked about the usage of mutex wrapper, condition_variable's wait and notify, and thread initialization. In addition, spurious wake-up of condition variables and a basic implementation of a thread pool are also mentioned. 5. Have you used template programming before? Let’s talk about C++ template programming. Answer: Used. In addition to basic template classes and template functions, I have also implemented iterators and used template extraction techniques. Mainly refer to the anatomy of the STL template library.