.TH "std::weak_ptr< _Tp >" 3cxx "libstdc++" \" -*- nroff -*-
.ad l
.nh
.SH NAME
std::weak_ptr< _Tp > \- A non-owning observer for a pointer owned by a shared_ptr\&.  

.SH SYNOPSIS
.br
.PP
.PP
\fC#include <memory>\fP
.PP
Inherits std::__weak_ptr< _Tp, _Lp >\&.
.SS "Public Types"

.in +1c
.ti -1c
.RI "\fBusing\fP \fBelement_type\fP = \fBtypename\fP \fBremove_extent\fP< _Tp >::type"
.br
.in -1c
.SS "Public Member Functions"

.in +1c
.ti -1c
.RI "template<\fBtypename\fP \fB_Yp\fP , \fBtypename\fP  = _Constructible<const shared_ptr<_Yp>&>> \fBweak_ptr\fP (const \fBshared_ptr\fP< \fB_Yp\fP > &__r) noexcept"
.br
.ti -1c
.RI "\fBweak_ptr\fP (const \fBweak_ptr\fP &) noexcept=\fBdefault\fP"
.br
.ti -1c
.RI "template<\fBtypename\fP \fB_Yp\fP , \fBtypename\fP  = _Constructible<const weak_ptr<_Yp>&>> \fBweak_ptr\fP (const \fBweak_ptr\fP< \fB_Yp\fP > &__r) noexcept"
.br
.ti -1c
.RI "\fBweak_ptr\fP (\fBweak_ptr\fP &&) noexcept=\fBdefault\fP"
.br
.ti -1c
.RI "template<\fBtypename\fP \fB_Yp\fP , \fBtypename\fP  = _Constructible<weak_ptr<_Yp>>> \fBweak_ptr\fP (\fBweak_ptr\fP< \fB_Yp\fP > &&__r) noexcept"
.br
.ti -1c
.RI "bool \fBexpired\fP () const noexcept"
.br
.ti -1c
.RI "\fBshared_ptr\fP< _Tp > \fBlock\fP () const noexcept"
.br
.ti -1c
.RI "template<\fBtypename\fP \fB_Yp\fP > _Assignable< const \fBshared_ptr\fP< \fB_Yp\fP > & > \fBoperator=\fP (const \fBshared_ptr\fP< \fB_Yp\fP > &__r) noexcept"
.br
.ti -1c
.RI "\fBweak_ptr\fP & \fBoperator=\fP (const \fBweak_ptr\fP &__r) noexcept=\fBdefault\fP"
.br
.ti -1c
.RI "template<\fBtypename\fP \fB_Yp\fP > _Assignable< const \fBweak_ptr\fP< \fB_Yp\fP > & > \fBoperator=\fP (const \fBweak_ptr\fP< \fB_Yp\fP > &__r) noexcept"
.br
.ti -1c
.RI "\fBweak_ptr\fP & \fBoperator=\fP (\fBweak_ptr\fP &&__r) noexcept=\fBdefault\fP"
.br
.ti -1c
.RI "template<\fBtypename\fP \fB_Yp\fP > _Assignable< \fBweak_ptr\fP< \fB_Yp\fP > > \fBoperator=\fP (\fBweak_ptr\fP< \fB_Yp\fP > &&__r) noexcept"
.br
.ti -1c
.RI "template<\fBtypename\fP \fB_Tp1\fP > bool \fBowner_before\fP (const __shared_ptr< \fB_Tp1\fP, \fB_Lp\fP > &\fB__rhs\fP) const noexcept"
.br
.ti -1c
.RI "template<\fBtypename\fP \fB_Tp1\fP > bool \fBowner_before\fP (const __weak_ptr< \fB_Tp1\fP, \fB_Lp\fP > &\fB__rhs\fP) const noexcept"
.br
.ti -1c
.RI "\fBvoid\fP \fBreset\fP () noexcept"
.br
.ti -1c
.RI "\fBvoid\fP \fBswap\fP (__weak_ptr &\fB__s\fP) noexcept"
.br
.ti -1c
.RI "long \fBuse_count\fP () const noexcept"
.br
.in -1c
.SS "Related Symbols"
(Note that these are not member symbols\&.) 
.in +1c
.ti -1c
.RI "template<\fBtypename\fP _Tp > \fBvoid\fP \fBswap\fP (\fBweak_ptr\fP< _Tp > &__a, \fBweak_ptr\fP< _Tp > &__b) noexcept"
.br
.RI "Swap overload for weak_ptr\&. "
.in -1c
.SH "Detailed Description"
.PP 

.SS "template<\fBtypename\fP _Tp>
.br
class std::weak_ptr< _Tp >"A non-owning observer for a pointer owned by a shared_ptr\&. 


.PP
\fBSince\fP
.RS 4
C++11
.RE
.PP
A weak_ptr provides a safe alternative to a raw pointer when you want a non-owning reference to an object that is managed by a shared_ptr\&.
.PP
Unlike a raw pointer, a weak_ptr can be converted to a new shared_ptr that shares ownership with every other shared_ptr that already owns the pointer\&. In other words you can upgrade from a non-owning 'weak' reference to an owning shared_ptr, without having access to any of the existing shared_ptr objects\&.
.PP
Also unlike a raw pointer, a weak_ptr does not become 'dangling' after the object it points to has been destroyed\&. Instead, a weak_ptr becomes \fIexpired\fP and can no longer be converted to a shared_ptr that owns the freed pointer, so you cannot accidentally access the pointed-to object after it has been destroyed\&. 

.SH "Author"
.PP 
Generated automatically by Doxygen for libstdc++ from the source code\&.