std::auto_ptr<T>::operator auto_ptr<Y>

template< class Y >
operator auto_ptr_ref<Y>() throw();
 (1) (deprecated in C++11)
(removed in C++17) 
template< class Y >
operator auto_ptr<Y>() throw();
 (2) (deprecated in C++11)
(removed in C++17)

Converts *this to an auto_ptr for a different type Y.

1) Returns an implementation-defined type that holds a reference to *this. std::auto_ptr is convertible and assignable from this template. The implementation is allowed to provide the template with a different name or implement equivalent functionality in other ways.
2) Constructs a new auto_ptr with a pointer obtained by calling release().

Parameters

(none).

Return value

1) An implementation-defined type that holds a reference to *this
2) A auto_ptr with a pointer obtained by calling release().

Notes

The constructor and the copy assignment operator from auto_ptr_ref is provided to allow copy-constructing and assigning std::auto_ptr from nameless temporaries. Since its copy constructor and copy assignment operator take the argument as non-const reference, they cannot bind rvalue arguments directly. However, a user-defined conversion can be executed (which releases the original auto_ptr), followed by a call to the constructor or copy-assignment operator that take auto_ptr_ref by value. This is an early implementation of move semantics.

© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
http://en.cppreference.com/w/cpp/memory/auto_ptr/operator_auto_ptr