If a shared_ptr is declared twice managing the same object, why does the count not increase to two, since the same object is being managed?
int i = 1;
std::shared_ptr<int> p1 = std::make_shared<int>(i);
std::shared_ptr<int> p2 = std::make_shared<int>(i);
std::cout << p1.use_count() << std::endl;
In the obove the the count is 1, not 2.
You create 2 different pointers, the make_shared() function creates a new pointer, not copies it. To make the p2 pointer refer to the p1 pointer, you must use the copy constructor, and shared_ptr must refer to a pointer in which case a new int is created instead of i:
std::shared_ptr<int> p1 = std::make_shared<int>(i);
std::shared_ptr<int> p2 = p1; // copy and increment the counter
//p1.use_count(); == 2
in order to refer to the original i you have to:
int* i = new int (1);
std::shared_ptr<int> p1(i); // means to refer to an existing pointer
std::shared_ptr<int> p2 = p1;
//p1.use_count(); == 2