# std::auto_ptr<T>::auto_ptr

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< cpp‎ | memory‎ | auto ptr

explicit auto_ptr( X* p = 0 ) throw(); | (1) | (deprecated in C++11) (removed in C++17)
auto_ptr( auto_ptr& r ) throw(); | (2) | (deprecated in C++11) (removed in C++17)
template< class Y > auto_ptr( auto_ptr<Y>& r ) throw(); | (3) | (deprecated in C++11) (removed in C++17)
auto_ptr( auto_ptr_ref<X> m ) throw(); | (4) | (deprecated in C++11) (removed in C++17)

Constructs the `auto_ptr` from a pointer that refers to the object to manage.

1) Constructs the `auto_ptr` with pointer `p`.
2) Constructs the `auto_ptr` with the pointer held in `r`. r.release() is called to acquire the ownership of the object.
3) Same as (2). Y* must be implicitly convertible to T*.
4) Constructs the `auto_ptr` with the pointer held in the `auto_ptr` instance referred to by `m`. p.release() is called for the `auto_ptr p` that `m` holds to acquire the ownership of the object.
`auto_ptr_ref` is an implementation-defined type that holds a reference to `auto_ptr`. std::auto_ptr is implicitly convertible to and assignable from this type. The implementation is allowed to provide the template with a different name or implement equivalent functionality in other ways.

### Parameters

p | - | a pointer to an object to manage
r | - | another `auto_ptr` to transfer the ownership of the object from
m | - | an implementation-defined type that holds a reference to `auto_ptr`

### 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.

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