std::shared_ptr< _Tp >(3)

NAME
std::shared_ptr< _Tp > - A smart pointer with reference-counted copy semantics.

SYNOPSIS

Inherits std::__shared_ptr< _Tp, _Lp >.

  Public Types
using element_type = typename __shared_ptr< _Tp >::element_type
The type pointed to by the stored pointer, remove_extent_t<_Tp>

  Public Member Functions
constexpr shared_ptr () noexcept
Construct an empty shared_ptr.
template<typename _Yp , typename = _Constructible<_Yp*>> shared_ptr (_Yp *__p)
Construct a shared_ptr that owns the pointer __p.
template<typename _Yp , typename _Deleter , typename = _Constructible<_Yp*, _Deleter>> shared_ptr (_Yp *__p, _Deleter __d)
Construct a shared_ptr that owns the pointer __p and the deleter __d.
template<typename _Yp , typename _Deleter , typename _Alloc , typename = _Constructible<_Yp*, _Deleter, _Alloc>> shared_ptr (_Yp *__p, _Deleter __d, _Alloc __a)
Construct a shared_ptr that owns the pointer __p and the deleter __d.
shared_ptr (const shared_ptr &) noexcept=default
Copy constructor.
template<typename _Yp , typename = _Constructible<const shared_ptr<_Yp>&>> shared_ptr (const shared_ptr< _Yp > &__r) noexcept
If __r is empty, constructs an empty shared_ptr; otherwise construct a shared_ptr that shares ownership with __r.
template<typename _Yp > shared_ptr (const shared_ptr< _Yp > &__r, element_type *__p) noexcept
Constructs a shared_ptr instance that stores __p and shares ownership with __r.
template<typename _Yp , typename = _Constructible<const weak_ptr<_Yp>&>> shared_ptr (const weak_ptr< _Yp > &__r)
Constructs a shared_ptr that shares ownership with __r and stores a copy of the pointer stored in __r.
template<typename _Deleter > shared_ptr (nullptr_t __p, _Deleter __d)
Construct a shared_ptr that owns a null pointer and the deleter __d.
template<typename _Deleter , typename _Alloc > shared_ptr (nullptr_t __p, _Deleter __d, _Alloc __a)
Construct a shared_ptr that owns a null pointer and the deleter __d.
constexpr shared_ptr (nullptr_t) noexcept
Construct an empty shared_ptr.
shared_ptr (shared_ptr &&__r) noexcept
Move-constructs a shared_ptr instance from __r.
template<typename _Yp , typename = _Constructible<shared_ptr<_Yp>>> shared_ptr (shared_ptr< _Yp > &&__r) noexcept
Move-constructs a shared_ptr instance from __r.
template<typename _Tp1 , typename > shared_ptr (std::auto_ptr< _Tp1 > &&__r)
template<typename _Yp , typename _Del , typename = _Constructible<unique_ptr<_Yp, _Del>>> shared_ptr (unique_ptr< _Yp, _Del > &&__r)
element_type * get () const noexcept
Return the stored pointer.
operator bool () const
Return true if the stored pointer is not null.
shared_ptr & operator= (const shared_ptr &) noexcept=default
template<typename _Yp > _Assignable< const shared_ptr< _Yp > & > operator= (const shared_ptr< _Yp > &__r) noexcept
shared_ptr & operator= (shared_ptr &&__r) noexcept
template<class _Yp > _Assignable< shared_ptr< _Yp > > operator= (shared_ptr< _Yp > &&__r) noexcept
template<typename _Yp , typename _Del > _Assignable< unique_ptr< _Yp, _Del > > operator= (unique_ptr< _Yp, _Del > &&__r)
void reset () noexcept
template<typename _Yp > _SafeConv< _Yp > reset (_Yp *__p)
template<typename _Yp , typename _Deleter > _SafeConv< _Yp > reset (_Yp *__p, _Deleter __d)
template<typename _Yp , typename _Deleter , typename _Alloc > _SafeConv< _Yp > reset (_Yp *__p, _Deleter __d, _Alloc __a)
void swap (__shared_ptr< _Tp, _Lp > &__other) noexcept
Exchange both the owned pointer and the stored pointer.
bool unique () const noexcept
Return true if use_count() == 1.
long use_count () const noexcept
If *this owns a pointer, return the number of owners, otherwise zero.

  Friends
template<typename _Yp , typename _Alloc , typename... _Args> shared_ptr< _Yp > allocate_shared (const _Alloc &__a, _Args &&... __args)
class weak_ptr< _Tp >

  Related Functions
(Note that these are not member functions.)
template<typename _Del , typename _Tp > _Del * get_deleter (const shared_ptr< _Tp > &__p) noexcept
20.7.2.2.10 shared_ptr get_deleter
template<typename _Ch , typename _Tr , typename _Tp , _Lock_policy _Lp> std::basic_ostream< _Ch, _Tr > & operator<< (std::basic_ostream< _Ch, _Tr > &__os, const __shared_ptr< _Tp, _Lp > &__p)
Write the stored pointer to an ostream.

template<typename _Tp , typename _Up > bool operator== (const shared_ptr< _Tp > &__a, const shared_ptr< _Up > &__b) noexcept
Equality operator for shared_ptr objects, compares the stored pointers.
template<typename _Tp > bool operator== (const shared_ptr< _Tp > &__a, nullptr_t) noexcept
shared_ptr comparison with nullptr
template<typename _Tp > bool operator== (nullptr_t, const shared_ptr< _Tp > &__a) noexcept
shared_ptr comparison with nullptr
template<typename _Tp , typename _Up > bool operator!= (const shared_ptr< _Tp > &__a, const shared_ptr< _Up > &__b) noexcept
Inequality operator for shared_ptr objects, compares the stored pointers.
template<typename _Tp > bool operator!= (const shared_ptr< _Tp > &__a, nullptr_t) noexcept
shared_ptr comparison with nullptr
template<typename _Tp > bool operator!= (nullptr_t, const shared_ptr< _Tp > &__a) noexcept
shared_ptr comparison with nullptr
template<typename _Tp , typename _Up > bool operator< (const shared_ptr< _Tp > &__a, const shared_ptr< _Up > &__b) noexcept
Relational operator for shared_ptr objects, compares the stored pointers.
template<typename _Tp > bool operator< (const shared_ptr< _Tp > &__a, nullptr_t) noexcept
shared_ptr comparison with nullptr
template<typename _Tp > bool operator< (nullptr_t, const shared_ptr< _Tp > &__a) noexcept
shared_ptr comparison with nullptr
template<typename _Tp , typename _Up > bool operator<= (const shared_ptr< _Tp > &__a, const shared_ptr< _Up > &__b) noexcept
Relational operator for shared_ptr objects, compares the stored pointers.
template<typename _Tp > bool operator<= (const shared_ptr< _Tp > &__a, nullptr_t) noexcept
shared_ptr comparison with nullptr
template<typename _Tp > bool operator<= (nullptr_t, const shared_ptr< _Tp > &__a) noexcept
shared_ptr comparison with nullptr
template<typename _Tp , typename _Up > bool operator> (const shared_ptr< _Tp > &__a, const shared_ptr< _Up > &__b) noexcept
Relational operator for shared_ptr objects, compares the stored pointers.
template<typename _Tp > bool operator> (const shared_ptr< _Tp > &__a, nullptr_t) noexcept
shared_ptr comparison with nullptr
template<typename _Tp > bool operator> (nullptr_t, const shared_ptr< _Tp > &__a) noexcept
shared_ptr comparison with nullptr
template<typename _Tp , typename _Up > bool operator>= (const shared_ptr< _Tp > &__a, const shared_ptr< _Up > &__b) noexcept
Relational operator for shared_ptr objects, compares the stored pointers.
template<typename _Tp > bool operator>= (const shared_ptr< _Tp > &__a, nullptr_t) noexcept
shared_ptr comparison with nullptr
template<typename _Tp > bool operator>= (nullptr_t, const shared_ptr< _Tp > &__a) noexcept
shared_ptr comparison with nullptr
template<typename _Tp > void swap (shared_ptr< _Tp > &__a, shared_ptr< _Tp > &__b) noexcept
Swap overload for shared_ptr.
template<typename _Tp , typename _Up > shared_ptr< _Tp > static_pointer_cast (const shared_ptr< _Up > &__r) noexcept
Convert type of shared_ptr, via static_cast
template<typename _Tp , typename _Up > shared_ptr< _Tp > const_pointer_cast (const shared_ptr< _Up > &__r) noexcept
Convert type of shared_ptr, via const_cast
template<typename _Tp , typename _Up > shared_ptr< _Tp > dynamic_pointer_cast (const shared_ptr< _Up > &__r) noexcept
Convert type of shared_ptr, via dynamic_cast
template<typename _Tp , typename _Alloc , typename... _Args> shared_ptr< _Tp > allocate_shared (const _Alloc &__a, _Args &&... __args)
Create an object that is owned by a shared_ptr.
template<typename _Tp , typename... _Args> shared_ptr< _Tp > make_shared (_Args &&... __args)
Create an object that is owned by a shared_ptr.

template<typename _Tp , _Lock_policy _Lp> bool atomic_is_lock_free (const __shared_ptr< _Tp, _Lp > *__p)
Report whether shared_ptr atomic operations are lock-free.
template<typename _Tp > shared_ptr< _Tp > atomic_load_explicit (const shared_ptr< _Tp > *__p, memory_order)
Atomic load for shared_ptr objects.
template<typename _Tp > void atomic_store_explicit (shared_ptr< _Tp > *__p, shared_ptr< _Tp > __r, memory_order)
Atomic store for shared_ptr objects.
template<typename _Tp > shared_ptr< _Tp > atomic_exchange_explicit (shared_ptr< _Tp > *__p, shared_ptr< _Tp > __r, memory_order)
Atomic exchange for shared_ptr objects.
template<typename _Tp > bool atomic_compare_exchange_strong_explicit (shared_ptr< _Tp > *__p, shared_ptr< _Tp > *__v, shared_ptr< _Tp > __w, memory_order, memory_order)
Atomic compare-and-swap for shared_ptr objects.

Detailed Description

  template<typename _Tp>
class std::shared_ptr< _Tp >" A smart pointer with reference-counted copy semantics. A shared_ptr object is either empty or owns a pointer passed to the constructor. Copies of a shared_ptr share ownership of the same pointer. When the last shared_ptr that owns the pointer is destroyed or reset, the owned pointer is freed (either by delete or by invoking a custom deleter that was passed to the constructor).

A shared_ptr also stores another pointer, which is usually (but not always) the same pointer as it owns. The stored pointer can be retrieved by calling the get() member function.

The equality and relational operators for shared_ptr only compare the stored pointer returned by get(), not the owned pointer. To test whether two shared_ptr objects share ownership of the same pointer see std::shared_ptr::owner_before and std::owner_less.

Definition at line 121 of file bits/shared_ptr.h.

Member Function Documentation

  template<typename _Tp , _Lock_policy _Lp> element_type* std::__shared_ptr< _Tp, _Lp >::get () const [inline], [noexcept], [inherited]

Return the stored pointer.

Definition at line 1324 of file shared_ptr_base.h.

  template<typename _Tp , _Lock_policy _Lp> std::__shared_ptr< _Tp, _Lp >::operator bool () const [inline], [explicit], [inherited]

Return true if the stored pointer is not null.

Definition at line 1328 of file shared_ptr_base.h.

  template<typename _Tp , _Lock_policy _Lp> template<typename _Tp1 > bool std::__shared_ptr< _Tp, _Lp >::owner_before (__shared_ptr< _Tp1, _Lp > const & __rhs) const [inline], [noexcept], [inherited]

Define an ordering based on ownership. This function defines a strict weak ordering between two shared_ptr or weak_ptr objects, such that one object is less than the other unless they share ownership of the same pointer, or are both empty.

Definition at line 1358 of file shared_ptr_base.h.

  template<typename _Tp , _Lock_policy _Lp> template<typename _Tp1 > bool std::__shared_ptr< _Tp, _Lp >::owner_before (__weak_ptr< _Tp1, _Lp > const & __rhs) const [inline], [noexcept], [inherited]

Define an ordering based on ownership. This function defines a strict weak ordering between two shared_ptr or weak_ptr objects, such that one object is less than the other unless they share ownership of the same pointer, or are both empty.

Definition at line 1363 of file shared_ptr_base.h.

  template<typename _Tp , _Lock_policy _Lp> void std::__shared_ptr< _Tp, _Lp >::swap (__shared_ptr< _Tp, _Lp > & __other) [inline], [noexcept], [inherited]

Exchange both the owned pointer and the stored pointer.

Definition at line 1343 of file shared_ptr_base.h.

  template<typename _Tp , _Lock_policy _Lp> bool std::__shared_ptr< _Tp, _Lp >::unique () const [inline], [noexcept], [inherited]

Return true if use_count() == 1.

Definition at line 1333 of file shared_ptr_base.h.

  template<typename _Tp , _Lock_policy _Lp> long std::__shared_ptr< _Tp, _Lp >::use_count () const [inline], [noexcept], [inherited]

If *this owns a pointer, return the number of owners, otherwise zero.

Definition at line 1338 of file shared_ptr_base.h.

Author

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