std::weak_ptr::reset(3)

NAME
std::weak_ptr::reset - std::weak_ptr::reset

Synopsis
   void reset() noexcept; (since C++11)
   Releases the reference to the managed object. After the call *this manages no
   object.

Parameters
   (none)

Return value
   (none)

Example
// Run this code
 #include <iostream>
 #include <memory>
 int main()
 {
     auto shared = std::make_shared<int>(), shared2 = shared, shared3 = shared2;
     auto weak = std::weak_ptr<int>{shared};
     std::cout << std::boolalpha
               << "shared.use_count(): " << shared.use_count() << '\n'
               << "weak.use_count(): " << weak.use_count() << '\n'
               << "weak.expired(): " << weak.expired() << '\n';
     weak.reset();
     std::cout << "weak.reset();\n"
               << "shared.use_count(): " << shared.use_count() << '\n'
               << "weak.use_count(): " << weak.use_count() << '\n'
               << "weak.expired(): " << weak.expired() << '\n';
 }

Output:
 shared.use_count(): 3
 weak.use_count(): 3
 weak.expired(): false
 weak.reset();
 shared.use_count(): 3
 weak.use_count(): 0
 weak.expired(): true

See also
   expired checks whether the referenced object was already deleted
           (public member function)