what's the difference between shared_ptr and weak_ptr

[puzzlecracker]

When would you use which?

[raj s]

On Jul 28, 5:41*pm, puzzlecracker <[e-mail]:

When would you use which?

#include <iostream>
#include <boost/shared_ptr.hpp>
#include <boost/weak_ptr.hpp>
using boost::shared_ptr;
using std::cin;
using std::cout;
class a{
public:
boost::weak_ptr<aclass_member;

};
int main() {
shared_ptr<amainvar(new a);
cout<<mainvar.use_count();
mainvar->class_member = mainvar;
cout<<mainvar.use_count();
cout<<mainvar->class_member.use_count();
int a;
cin>>a;
}

in the above code weak_ptr is the must. Even when mainvar pointer goes
out of scope the reference count is still 1 since it is pointed by
class_member(shared_ptr)
to avoid this use class_member(weak_ptr) which in first does not
increase the reference count.