std::shared_ptr< _Tp > Class Template Reference

#include <memory>

Public Types
using	element_type
using	weak_type

Public Member Functions
constexpr	shared_ptr () noexcept
template<typename _Yp, typename = _Constructible<_Yp*>>
	shared_ptr (_Yp *__p)
template<typename _Yp, typename _Deleter, typename = _Constructible<_Yp*, _Deleter>>
	shared_ptr (_Yp *__p, _Deleter __d)
template<typename _Yp, typename _Deleter, typename _Alloc, typename = _Constructible<_Yp*, _Deleter, _Alloc>>
	shared_ptr (_Yp *__p, _Deleter __d, _Alloc __a)
template<typename _Yp, typename = _Constructible<auto_ptr<_Yp>>>
	shared_ptr (auto_ptr< _Yp > &&__r)
	shared_ptr (const shared_ptr &) noexcept=default
template<typename _Yp, typename = _Constructible<const shared_ptr<_Yp>&>>
	shared_ptr (const shared_ptr< _Yp > &__r) noexcept
template<typename _Yp>
	shared_ptr (const shared_ptr< _Yp > &__r, element_type *__p) noexcept
template<typename _Yp, typename = _Constructible<const weak_ptr<_Yp>&>>
	shared_ptr (const weak_ptr< _Yp > &__r)
template<typename _Deleter>
	shared_ptr (nullptr_t __p, _Deleter __d)
template<typename _Deleter, typename _Alloc>
	shared_ptr (nullptr_t __p, _Deleter __d, _Alloc __a)
constexpr	shared_ptr (nullptr_t) noexcept
	shared_ptr (shared_ptr &&__r) noexcept
template<typename _Yp, typename = _Constructible<shared_ptr<_Yp>>>
	shared_ptr (shared_ptr< _Yp > &&__r) noexcept
template<typename _Yp>
	shared_ptr (shared_ptr< _Yp > &&__r, element_type *__p) noexcept
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
	operator bool () const noexcept
element_type &	operator* () const noexcept
element_type *	operator-> () const noexcept
template<typename _Yp>
_Assignable< auto_ptr< _Yp > >	operator= (auto_ptr< _Yp > &&__r)
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
bool	unique () const noexcept
long	use_count () const noexcept
template<typename _Tp1>
bool	owner_before (__shared_ptr< _Tp1, _Lp > const &__rhs) const noexcept
template<typename _Tp1>
bool	owner_before (__weak_ptr< _Tp1, _Lp > const &__rhs) const noexcept

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

Related Symbols
(Note that these are not member symbols.)
template<typename _Del, typename _Tp>
_Del *	get_deleter (const shared_ptr< _Tp > &__p) noexcept
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)
template<typename _Tp, typename _Up>
bool	operator== (const shared_ptr< _Tp > &__a, const shared_ptr< _Up > &__b) noexcept
template<typename _Tp>
bool	operator== (const shared_ptr< _Tp > &__a, nullptr_t) noexcept
template<typename _Tp>
void	swap (shared_ptr< _Tp > &__a, shared_ptr< _Tp > &__b) noexcept
template<typename _Tp, typename _Up>
shared_ptr< _Tp >	static_pointer_cast (const shared_ptr< _Up > &__r) noexcept
template<typename _Tp, typename _Up>
shared_ptr< _Tp >	const_pointer_cast (const shared_ptr< _Up > &__r) noexcept
template<typename _Tp, typename _Up>
shared_ptr< _Tp >	dynamic_pointer_cast (const shared_ptr< _Up > &__r) noexcept
template<typename _Tp, typename _Up>
shared_ptr< _Tp >	reinterpret_pointer_cast (const shared_ptr< _Up > &__r) noexcept
template<typename _Tp, typename _Up>
shared_ptr< _Tp >	static_pointer_cast (shared_ptr< _Up > &&__r) noexcept
template<typename _Tp, typename _Up>
shared_ptr< _Tp >	const_pointer_cast (shared_ptr< _Up > &&__r) noexcept
template<typename _Tp, typename _Up>
shared_ptr< _Tp >	dynamic_pointer_cast (shared_ptr< _Up > &&__r) noexcept
template<typename _Tp, typename _Up>
shared_ptr< _Tp >	reinterpret_pointer_cast (shared_ptr< _Up > &&__r) noexcept
template<typename _Tp, typename _Alloc, typename... _Args>
shared_ptr< _NonArray< _Tp > >	allocate_shared (const _Alloc &__a, _Args &&... __args)
template<typename _Tp, typename... _Args>
shared_ptr< _NonArray< _Tp > >	make_shared (_Args &&... __args)

Detailed Description

template<typename _Tp>
class std::shared_ptr< _Tp >

A smart pointer with reference-counted copy semantics.

Since

C++11

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 175 of file bits/shared_ptr.h.

Member Typedef Documentation

element_type

template<typename _Tp>

using std::shared_ptr< _Tp >::element_type

The type pointed to by the stored pointer, remove_extent_t<_Tp>

Definition at line 190 of file bits/shared_ptr.h.

weak_type

template<typename _Tp, _Lock_policy _Lp>

using std::__shared_ptr< _Tp, _Lp >::weak_type

inherited

Definition at line 1480 of file shared_ptr_base.h.

Constructor & Destructor Documentation

shared_ptr() [1/16]

template<typename _Tp>

std::shared_ptr< _Tp >::shared_ptr ( )

inlineconstexprnoexcept

Construct an empty shared_ptr.

Postcondition

use_count()==0 && get()==0

Definition at line 201 of file bits/shared_ptr.h.

shared_ptr() [2/16]

template<typename _Tp>

std::shared_ptr< _Tp >::shared_ptr ( const shared_ptr< _Tp > & )

defaultnoexcept

Copy constructor.

shared_ptr() [3/16]

template<typename _Tp>

template<typename _Yp, typename = _Constructible<_Yp*>>

std::shared_ptr< _Tp >::shared_ptr ( _Yp * __p )

inlineexplicit

Construct a shared_ptr that owns the pointer __p.

Parameters

__p	A pointer that is convertible to element_type*.

Postcondition

use_count() == 1 && get() == __p

Exceptions

std::bad_alloc,in

which case delete __p is called.

Definition at line 213 of file bits/shared_ptr.h.

shared_ptr() [4/16]

template<typename _Tp>

template<typename _Yp, typename _Deleter, typename = _Constructible<_Yp*, _Deleter>>

std::shared_ptr< _Tp >::shared_ptr ( _Yp * __p, _Deleter __d )

inline

Construct a shared_ptr that owns the pointer __p and the deleter __d.

Parameters

__p	A pointer.
__d	A deleter.

Postcondition

use_count() == 1 && get() == __p

Exceptions

std::bad_alloc,in

which case __d(__p) is called.

Requirements: _Deleter's copy constructor and destructor must not throw

__shared_ptr will release __p by calling __d(__p)

Definition at line 230 of file bits/shared_ptr.h.

shared_ptr() [5/16]

template<typename _Tp>

template<typename _Deleter>

std::shared_ptr< _Tp >::shared_ptr ( nullptr_t __p, _Deleter __d )

inline

Construct a shared_ptr that owns a null pointer and the deleter __d.

Parameters

__p	A null pointer constant.
__d	A deleter.

Postcondition

use_count() == 1 && get() == __p

Exceptions

std::bad_alloc,in

which case __d(__p) is called.

Requirements: _Deleter's copy constructor and destructor must not throw

The last owner will call __d(__p)

Definition at line 247 of file bits/shared_ptr.h.

shared_ptr() [6/16]

template<typename _Tp>

template<typename _Yp, typename _Deleter, typename _Alloc, typename = _Constructible<_Yp*, _Deleter, _Alloc>>

std::shared_ptr< _Tp >::shared_ptr ( _Yp * __p, _Deleter __d, _Alloc __a )

inline

Construct a shared_ptr that owns the pointer __p and the deleter __d.

Parameters

__p	A pointer.
__d	A deleter.
__a	An allocator.

Postcondition

use_count() == 1 && get() == __p

Exceptions

std::bad_alloc,in

which case __d(__p) is called.

Requirements: _Deleter's copy constructor and destructor must not throw _Alloc's copy constructor and destructor must not throw.

__shared_ptr will release __p by calling __d(__p)

Definition at line 267 of file bits/shared_ptr.h.

shared_ptr() [7/16]

template<typename _Tp>

template<typename _Deleter, typename _Alloc>

std::shared_ptr< _Tp >::shared_ptr ( nullptr_t __p, _Deleter __d, _Alloc __a )

inline

Construct a shared_ptr that owns a null pointer and the deleter __d.

Parameters

__p	A null pointer constant.
__d	A deleter.
__a	An allocator.

Postcondition

use_count() == 1 && get() == __p

Exceptions

std::bad_alloc,in

which case __d(__p) is called.

Requirements: _Deleter's copy constructor and destructor must not throw _Alloc's copy constructor and destructor must not throw.

The last owner will call __d(__p)

Definition at line 286 of file bits/shared_ptr.h.

shared_ptr() [8/16]

template<typename _Tp>

template<typename _Yp>

std::shared_ptr< _Tp >::shared_ptr ( const shared_ptr< _Yp > & __r, element_type * __p )

inlinenoexcept

Constructs a shared_ptr instance that stores __p and shares ownership with __r.

Parameters

__r	A shared_ptr.
__p	A pointer that will remain valid while *__r is valid.

Postcondition

get() == __p && use_count() == __r.use_count()

This can be used to construct a shared_ptr to a sub-object of an object managed by an existing shared_ptr. The complete object will remain valid while any shared_ptr owns it, even if they don't store a pointer to the complete object.

shared_ptr<pair<int,int>> pii(new pair<int,int>());
shared_ptr<int> pi(pii, &pii->first);
assert(pii.use_count() == 2);

Definition at line 310 of file bits/shared_ptr.h.

shared_ptr() [9/16]

template<typename _Tp>

template<typename _Yp>

std::shared_ptr< _Tp >::shared_ptr ( shared_ptr< _Yp > && __r, element_type * __p )

inlinenoexcept

Constructs a shared_ptr instance that stores __p and shares ownership with __r.

Parameters

__r	A shared_ptr.
__p	A pointer that will remain valid while *__r is valid.

Postcondition

get() == __p && !__r.use_count() && !__r.get()

Since

C++17

This can be used to construct a shared_ptr to a sub-object of an object managed by an existing shared_ptr. The complete object will remain valid while any shared_ptr owns it, even if they don't store a pointer to the complete object.

shared_ptr<pair<int,int>> pii(new pair<int,int>());
shared_ptr<int> pi1(pii, &pii->first);
assert(pii.use_count() == 2);
shared_ptr<int> pi2(std::move(pii), &pii->second);
assert(pii.use_count() == 0);

Definition at line 338 of file bits/shared_ptr.h.

shared_ptr() [10/16]

template<typename _Tp>

template<typename _Yp, typename = _Constructible<const shared_ptr<_Yp>&>>

std::shared_ptr< _Tp >::shared_ptr ( const shared_ptr< _Yp > & __r )

inlinenoexcept

If __r is empty, constructs an empty shared_ptr; otherwise construct a shared_ptr that shares ownership with __r.

Parameters

__r	A shared_ptr.

Postcondition

get() == __r.get() && use_count() == __r.use_count()

Definition at line 350 of file bits/shared_ptr.h.

shared_ptr() [11/16]

template<typename _Tp>

std::shared_ptr< _Tp >::shared_ptr ( shared_ptr< _Tp > && __r )

inlinenoexcept

Move-constructs a shared_ptr instance from __r.

Parameters

__r	A shared_ptr rvalue.

Postcondition

*this contains the old value of __r, __r is empty.

Definition at line 358 of file bits/shared_ptr.h.

shared_ptr() [12/16]

template<typename _Tp>

template<typename _Yp, typename = _Constructible<shared_ptr<_Yp>>>

std::shared_ptr< _Tp >::shared_ptr ( shared_ptr< _Yp > && __r )

inlinenoexcept

Move-constructs a shared_ptr instance from __r.

Parameters

__r	A shared_ptr rvalue.

Postcondition

*this contains the old value of __r, __r is empty.

Definition at line 367 of file bits/shared_ptr.h.

shared_ptr() [13/16]

template<typename _Tp>

template<typename _Yp, typename = _Constructible<const weak_ptr<_Yp>&>>

std::shared_ptr< _Tp >::shared_ptr ( const weak_ptr< _Yp > & __r )

inlineexplicit

Constructs a shared_ptr that shares ownership with __r and stores a copy of the pointer stored in __r.

Parameters

__r	A weak_ptr.

Postcondition

use_count() == __r.use_count()

Exceptions

bad_weak_ptr

when __r.expired(), in which case the constructor has no effect.

Definition at line 379 of file bits/shared_ptr.h.

shared_ptr() [14/16]

template<typename _Tp>

template<typename _Yp, typename _Del, typename = _Constructible<unique_ptr<_Yp, _Del>>>

std::shared_ptr< _Tp >::shared_ptr ( unique_ptr< _Yp, _Del > && __r )

inline

Definition at line 394 of file bits/shared_ptr.h.

shared_ptr() [15/16]

template<typename _Tp>

std::shared_ptr< _Tp >::shared_ptr ( nullptr_t )

inlineconstexprnoexcept

Construct an empty shared_ptr.

Postcondition

use_count() == 0 && get() == nullptr

Definition at line 411 of file bits/shared_ptr.h.

shared_ptr() [16/16]

template<typename _Tp>

template<typename _Tp1, typename>

std::shared_ptr< _Tp >::shared_ptr ( std::auto_ptr< _Tp1 > && __r )

inline

Definition at line 327 of file auto_ptr.h.

Member Function Documentation

get()

template<typename _Tp, _Lock_policy _Lp>

element_type * std::__shared_ptr< _Tp, _Lp >::get ( ) const

inlinenoexceptinherited

Return the stored pointer.

Definition at line 1686 of file shared_ptr_base.h.

operator bool()

template<typename _Tp, _Lock_policy _Lp>

std::__shared_ptr< _Tp, _Lp >::operator bool ( ) const

inlineexplicitnoexceptinherited

Return true if the stored pointer is not null.

Definition at line 1690 of file shared_ptr_base.h.

operator*()

template<typename _Tp, _Lock_policy _Lp, bool = is_array<_Tp>::value, bool = is_void<_Tp>::value>

element_type & std::__shared_ptr_access< _Tp, _Lp, bool, bool >::operator* ( ) const

inlinenoexceptinherited

Definition at line 1372 of file shared_ptr_base.h.

operator->()

template<typename _Tp, _Lock_policy _Lp, bool = is_array<_Tp>::value, bool = is_void<_Tp>::value>

element_type * std::__shared_ptr_access< _Tp, _Lp, bool, bool >::operator-> ( ) const

inlinenoexceptinherited

Definition at line 1376 of file shared_ptr_base.h.

operator=() [1/5]

template<typename _Tp>

template<typename _Yp>

_Assignable< auto_ptr< _Yp > > std::shared_ptr< _Tp >::operator= ( auto_ptr< _Yp > && __r )

inline

Definition at line 428 of file bits/shared_ptr.h.

operator=() [2/5]

template<typename _Tp>

template<typename _Yp>

_Assignable< const shared_ptr< _Yp > & > std::shared_ptr< _Tp >::operator= ( const shared_ptr< _Yp > & __r )

inlinenoexcept

Definition at line 417 of file bits/shared_ptr.h.

operator=() [3/5]

template<typename _Tp>

shared_ptr & std::shared_ptr< _Tp >::operator= ( shared_ptr< _Tp > && __r )

inlinenoexcept

Definition at line 437 of file bits/shared_ptr.h.

operator=() [4/5]

template<typename _Tp>

template<class _Yp>

_Assignable< shared_ptr< _Yp > > std::shared_ptr< _Tp >::operator= ( shared_ptr< _Yp > && __r )

inlinenoexcept

Definition at line 445 of file bits/shared_ptr.h.

operator=() [5/5]

template<typename _Tp>

template<typename _Yp, typename _Del>

_Assignable< unique_ptr< _Yp, _Del > > std::shared_ptr< _Tp >::operator= ( unique_ptr< _Yp, _Del > && __r )

inline

Definition at line 453 of file bits/shared_ptr.h.

owner_before() [1/2]

template<typename _Tp, _Lock_policy _Lp>

template<typename _Tp1>

bool std::__shared_ptr< _Tp, _Lp >::owner_before ( __shared_ptr< _Tp1, _Lp > const & __rhs ) const

inlinenoexceptinherited

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 1720 of file shared_ptr_base.h.

owner_before() [2/2]

template<typename _Tp, _Lock_policy _Lp>

template<typename _Tp1>

bool std::__shared_ptr< _Tp, _Lp >::owner_before ( __weak_ptr< _Tp1, _Lp > const & __rhs ) const

inlinenoexceptinherited

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 1725 of file shared_ptr_base.h.

reset() [1/4]

template<typename _Tp, _Lock_policy _Lp>

void std::__shared_ptr< _Tp, _Lp >::reset ( )

inlinenoexceptinherited

Definition at line 1662 of file shared_ptr_base.h.

reset() [2/4]

template<typename _Tp, _Lock_policy _Lp>

template<typename _Yp>

_SafeConv< _Yp > std::__shared_ptr< _Tp, _Lp >::reset ( _Yp * __p )

inlineinherited

Definition at line 1667 of file shared_ptr_base.h.

reset() [3/4]

template<typename _Tp, _Lock_policy _Lp>

template<typename _Yp, typename _Deleter>

_SafeConv< _Yp > std::__shared_ptr< _Tp, _Lp >::reset ( _Yp * __p, _Deleter __d )

inlineinherited

Definition at line 1676 of file shared_ptr_base.h.

reset() [4/4]

template<typename _Tp, _Lock_policy _Lp>

template<typename _Yp, typename _Deleter, typename _Alloc>

_SafeConv< _Yp > std::__shared_ptr< _Tp, _Lp >::reset ( _Yp * __p, _Deleter __d, _Alloc __a )

inlineinherited

Definition at line 1681 of file shared_ptr_base.h.

swap()

template<typename _Tp, _Lock_policy _Lp>

void std::__shared_ptr< _Tp, _Lp >::swap ( __shared_ptr< _Tp, _Lp > & __other )

inlinenoexceptinherited

Exchange both the owned pointer and the stored pointer.

Definition at line 1705 of file shared_ptr_base.h.

unique()

template<typename _Tp, _Lock_policy _Lp>

bool std::__shared_ptr< _Tp, _Lp >::unique ( ) const

inlinenoexceptinherited

Return true if use_count() == 1.

Definition at line 1695 of file shared_ptr_base.h.

use_count()

template<typename _Tp, _Lock_policy _Lp>

long std::__shared_ptr< _Tp, _Lp >::use_count ( ) const

inlinenoexceptinherited

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

Definition at line 1700 of file shared_ptr_base.h.

Friends And Related Symbol Documentation

weak_ptr< _Tp >

template<typename _Tp>

friend class weak_ptr< _Tp >

friend

Definition at line 534 of file bits/shared_ptr.h.

---

The documentation for this class was generated from the following files:

• bits/shared_ptr.h
• auto_ptr.h