C ++ questions Summary

 

3, the handwriting strcpy, memcpy, memmove function;

 

2, thread synchronization in several ways:

Mutex, semaphore, critical section

 

1, to achieve a vector, it is 1.5 or 2 times? What advantages and disadvantages:

(1) 1.5-fold advantage: it can reuse the release of allocated memory before;

(2) double disadvantage: memory each application can not be reused;

 

0, thread-safe singleton

class Singleton{
    private:
        static pthread_mutex_t mtx;
        static Singleton* instance;
        Singleton(){}
        ~Singleton(){}
    public:
        static Singleton* getInstance(){
            if(instance == NULL){
                pthread_mutex_lock(mtx);
                if(instance == NULL){
                    instance = new Singleton();
                }
                pthread_mutex_unlock(mtx);
            }
            return instance;
        }
};

pthread_mutex_t Singleton::mtx = PTHREAD_MUTEX_INITIALIZER;
Singleton Singleton::instance = NULL;