The Boost C++ Libraries
The library Boost.SmartPointers provides various smart pointers. They help you manage dynamically allocated objects, which are anchored in smart pointers that release the dynamically allocated objects in the destructor. Because destructors are executed when the scope of smart pointers ends, releasing dynamically allocated objects is guaranteed. There can’t be a memory leak if, for example, you forget to call delete.
The standard library has included the smart pointer std::auto_ptr since C++98, but since C++11, std::auto_ptr has been deprecated. With C++11, new and better smart pointers were introduced in the standard library. std::shared_ptr and std::weak_ptr originate from Boost.SmartPointers and are called boost::shared_ptr and boost::weak_ptr in this library. There is no counterpart to std::unique_ptr. However, Boost.SmartPointers provides four additional smart pointers – boost::scoped_ptr, boost::scoped_array, boost::shared_array, and boost::intrusive_ptr – which are not in the standard library.