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std::shared_ptr< _Tp >(3) Library Functions Manual 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

Public Member Functions


constexpr shared_ptr () noexcept
Construct an empty shared_ptr. shared_ptr (const shared_ptr &) noexcept=default
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 _Deleter > shared_ptr (nullptr_t __p, _Deleter __d)
Construct a shared_ptr that owns a null pointer 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. 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. 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 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. 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 _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 _Yp , typename _Del , typename = _Constructible<unique_ptr<_Yp, _Del>>> shared_ptr (unique_ptr< _Yp, _Del > &&__r)
constexpr shared_ptr (nullptr_t) noexcept
Construct an empty shared_ptr. template<typename _Tp1 , typename > shared_ptr (std::auto_ptr< _Tp1 > &&__r)
element_type * get () const noexcept
operator bool () const
element_type & operator* () const noexcept
element_type * operator-> () const noexcept
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)
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
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

Friends


template<typename _Yp , typename _Alloc , typename... _Args> shared_ptr< _Yp > allocate_shared (const _Alloc &__a, _Args &&... __args)
Create an object that is owned by a shared_ptr. class weak_ptr< _Tp >

Detailed Description

template<typename _Tp>

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

The object pointed to is deleted when the last shared_ptr pointing to it is destroyed or reset.

Definition at line 103 of file bits/shared_ptr.h.

Constructor & Destructor Documentation

template<typename _Tp> constexpr std::shared_ptr< _Tp >::shared_ptr () [inline], [noexcept]

Construct an empty shared_ptr.

Postcondition:

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

Definition at line 127 of file bits/shared_ptr.h.

template<typename _Tp> template<typename _Yp , typename = _Constructible<_Yp*>> std::shared_ptr< _Tp >::shared_ptr (_Yp * __p) [inline], [explicit]

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 139 of file bits/shared_ptr.h.

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 156 of file bits/shared_ptr.h.

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 173 of file bits/shared_ptr.h.

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 193 of file bits/shared_ptr.h.

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 212 of file bits/shared_ptr.h.

template<typename _Tp> template<typename _Yp > std::shared_ptr< _Tp >::shared_ptr (const shared_ptr< _Yp > & __r, element_type * __p) [inline], [noexcept]

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.

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 234 of file bits/shared_ptr.h.

template<typename _Tp> template<typename _Yp , typename = _Constructible<const shared_ptr<_Yp>&>> std::shared_ptr< _Tp >::shared_ptr (const shared_ptr< _Yp > & __r) [inline], [noexcept]

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 246 of file bits/shared_ptr.h.

template<typename _Tp> std::shared_ptr< _Tp >::shared_ptr (shared_ptr< _Tp > && __r) [inline], [noexcept]

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 254 of file bits/shared_ptr.h.

template<typename _Tp> template<typename _Yp , typename = _Constructible<shared_ptr<_Yp>>> std::shared_ptr< _Tp >::shared_ptr (shared_ptr< _Yp > && __r) [inline], [noexcept]

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 263 of file bits/shared_ptr.h.

template<typename _Tp> template<typename _Yp , typename = _Constructible<const weak_ptr<_Yp>&>> std::shared_ptr< _Tp >::shared_ptr (const weak_ptr< _Yp > & __r) [inline], [explicit]

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 275 of file bits/shared_ptr.h.

template<typename _Tp> constexpr std::shared_ptr< _Tp >::shared_ptr (nullptr_t) [inline], [noexcept]

Construct an empty shared_ptr.

Postcondition:

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

Definition at line 307 of file bits/shared_ptr.h.

Friends And Related Function Documentation

template<typename _Tp> template<typename _Yp , typename _Alloc , typename... _Args> shared_ptr<_Yp> allocate_shared (const _Alloc & __a, _Args &&... __args) [friend]

Create an object that is owned by a shared_ptr.

Parameters:

__a An allocator.
__args Arguments for the _Tp object's constructor.

Returns:

A shared_ptr that owns the newly created object.

Exceptions:

An exception thrown from _Alloc::allocate or from the constructor of _Tp.

A copy of __a will be used to allocate memory for the shared_ptr and the new object.

Definition at line 703 of file bits/shared_ptr.h.

Author

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