// shared_ptr is built-in RAII.
//
// A shared_ptr is a “counting pointer”.  It keeps track of how many
// shared owners this object has, via a counter.
//
// A new owner (via assignment) increments the counter.
// When any owner is destroyed, the counter decrements.
//
// When the counter goes to zero, there are no more owners,
// so the object itself is destroyed.
//
// You can assign a shared_ptr.  It just increments the use count.

#include <iostream>
#include <memory>

using namespace std;

// A class that tells you when instances are created or destroyed:
class Loud {
  public:
    Loud() { clog << "Loud::Loud()\n"; }
    ~Loud() { clog << "Loud::~Loud()\n"; }
};

int main() {
    shared_ptr<Loud> p(new Loud);
    cout << p.use_count() << '\n';
    {
	cout << p.use_count() << '\n';
	auto q=p;
	cout << p.use_count() << '\n';
    }
    cout << p.use_count() << '\n';
    return 0;
}