.TH "std::optional< _Tp >" 3cxx "Thu Feb 16 2023" "libstdc++" \" -*- nroff -*-
.ad l
.nh
.SH NAME
std::optional< _Tp > \- Class template for optional values\&.  

.SH SYNOPSIS
.br
.PP
.PP
Inherits \fBstd::_Optional_base< _Tp, bool, bool >\fP, and _Enable_copy_move< is_copy_constructible_v< _Tp >, __and_v< is_copy_constructible< _Tp >, is_copy_assignable< _Tp > >, is_move_constructible_v< _Tp >, __and_v< is_move_constructible< _Tp >, is_move_assignable< _Tp > >, optional< _Tp > >\&.
.SS "Public Types"

.in +1c
.ti -1c
.RI "using \fBvalue_type\fP = _Tp"
.br
.in -1c
.SS "Public Member Functions"

.in +1c
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.RI "template<typename _Up  = _Tp, _Requires< __not_self< _Up >, __not_tag< _Up >, \fBis_constructible\fP< _Tp, _Up >, \fBis_convertible\fP< _Up, _Tp > >  = true> constexpr \fBoptional\fP (_Up &&__t) noexcept(is_nothrow_constructible_v< _Tp, _Up >)"
.br
.ti -1c
.RI "template<typename _Up  = _Tp, _Requires< __not_self< _Up >, __not_tag< _Up >, \fBis_constructible\fP< _Tp, _Up >, __not_< \fBis_convertible\fP< _Up, _Tp > > >  = false> constexpr \fBoptional\fP (_Up &&__t) noexcept(is_nothrow_constructible_v< _Tp, _Up >)"
.br
.ti -1c
.RI "template<typename _Up , _Requires< __not_< \fBis_same\fP< _Tp, _Up > >, \fBis_constructible\fP< _Tp, const _Up & >, \fBis_convertible\fP< const _Up &, _Tp >, __not_< __converts_from_optional< _Tp, _Up > > >  = true> constexpr \fBoptional\fP (const \fBoptional\fP< _Up > &__t) noexcept(is_nothrow_constructible_v< _Tp, const _Up & >)"
.br
.ti -1c
.RI "template<typename _Up , _Requires< __not_< \fBis_same\fP< _Tp, _Up > >, \fBis_constructible\fP< _Tp, const _Up & >, __not_< \fBis_convertible\fP< const _Up &, _Tp > >, __not_< __converts_from_optional< _Tp, _Up > > >  = false> constexpr \fBoptional\fP (const \fBoptional\fP< _Up > &__t) noexcept(is_nothrow_constructible_v< _Tp, const _Up & >)"
.br
.ti -1c
.RI "template<typename\&.\&.\&. _Args, _Requires< \fBis_constructible\fP< _Tp, _Args\&.\&.\&. > >  = false> constexpr \fBoptional\fP (in_place_t, _Args &&\&.\&.\&. __args) noexcept(is_nothrow_constructible_v< _Tp, _Args\&.\&.\&. >)"
.br
.ti -1c
.RI "template<typename _Up , typename\&.\&.\&. _Args, _Requires< \fBis_constructible\fP< _Tp, \fBinitializer_list\fP< _Up > &, _Args\&.\&.\&. > >  = false> constexpr \fBoptional\fP (in_place_t, \fBinitializer_list\fP< _Up > __il, _Args &&\&.\&.\&. __args) noexcept(is_nothrow_constructible_v< _Tp, \fBinitializer_list\fP< _Up > &, _Args\&.\&.\&. >)"
.br
.ti -1c
.RI "constexpr \fBoptional\fP (\fBnullopt_t\fP) noexcept"
.br
.ti -1c
.RI "template<typename _Up , _Requires< __not_< \fBis_same\fP< _Tp, _Up > >, \fBis_constructible\fP< _Tp, _Up >, \fBis_convertible\fP< _Up, _Tp >, __not_< __converts_from_optional< _Tp, _Up > > >  = true> constexpr \fBoptional\fP (\fBoptional\fP< _Up > &&__t) noexcept(is_nothrow_constructible_v< _Tp, _Up >)"
.br
.ti -1c
.RI "template<typename _Up , _Requires< __not_< \fBis_same\fP< _Tp, _Up > >, \fBis_constructible\fP< _Tp, _Up >, __not_< \fBis_convertible\fP< _Up, _Tp > >, __not_< __converts_from_optional< _Tp, _Up > > >  = false> constexpr \fBoptional\fP (\fBoptional\fP< _Up > &&__t) noexcept(is_nothrow_constructible_v< _Tp, _Up >)"
.br
.ti -1c
.RI "template<typename\&.\&.\&. _Args> constexpr \fBenable_if_t\fP< is_constructible_v< _Tp, _Args\&.\&.\&. >, _Tp & > \fBemplace\fP (_Args &&\&.\&.\&. __args) noexcept(is_nothrow_constructible_v< _Tp, _Args\&.\&.\&. >)"
.br
.ti -1c
.RI "template<typename _Up , typename\&.\&.\&. _Args> constexpr \fBenable_if_t\fP< is_constructible_v< _Tp, \fBinitializer_list\fP< _Up > &, _Args\&.\&.\&. >, _Tp & > \fBemplace\fP (\fBinitializer_list\fP< _Up > __il, _Args &&\&.\&.\&. __args) noexcept(is_nothrow_constructible_v< _Tp, \fBinitializer_list\fP< _Up > &, _Args\&.\&.\&. >)"
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.RI "constexpr bool \fBhas_value\fP () const noexcept"
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.RI "constexpr \fBoperator bool\fP () const noexcept"
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.RI "constexpr _Tp && \fBoperator*\fP () &&noexcept"
.br
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.RI "constexpr _Tp & \fBoperator*\fP () &noexcept"
.br
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.RI "constexpr const _Tp && \fBoperator*\fP () const &&noexcept"
.br
.ti -1c
.RI "constexpr const _Tp & \fBoperator*\fP () const &noexcept"
.br
.ti -1c
.RI "constexpr const _Tp * \fBoperator\->\fP () const noexcept"
.br
.ti -1c
.RI "constexpr _Tp * \fBoperator\->\fP () noexcept"
.br
.ti -1c
.RI "template<typename _Up  = _Tp> constexpr \fBenable_if_t\fP< __and_v< __not_self< _Up >, __not_< __and_< \fBis_scalar\fP< _Tp >, \fBis_same\fP< _Tp, \fBdecay_t\fP< _Up > > > >, \fBis_constructible\fP< _Tp, _Up >, \fBis_assignable\fP< _Tp &, _Up > >, \fBoptional\fP & > \fBoperator=\fP (_Up &&__u) noexcept(__and_v< \fBis_nothrow_constructible\fP< _Tp, _Up >, \fBis_nothrow_assignable\fP< _Tp &, _Up > >)"
.br
.ti -1c
.RI "template<typename _Up > constexpr \fBenable_if_t\fP< __and_v< __not_< \fBis_same\fP< _Tp, _Up > >, \fBis_constructible\fP< _Tp, const _Up & >, \fBis_assignable\fP< _Tp &, const _Up & >, __not_< __converts_from_optional< _Tp, _Up > >, __not_< __assigns_from_optional< _Tp, _Up > > >, \fBoptional\fP & > \fBoperator=\fP (const \fBoptional\fP< _Up > &__u) noexcept(__and_v< \fBis_nothrow_constructible\fP< _Tp, const _Up & >, \fBis_nothrow_assignable\fP< _Tp &, const _Up & > >)"
.br
.ti -1c
.RI "constexpr \fBoptional\fP & \fBoperator=\fP (\fBnullopt_t\fP) noexcept"
.br
.ti -1c
.RI "template<typename _Up > constexpr \fBenable_if_t\fP< __and_v< __not_< \fBis_same\fP< _Tp, _Up > >, \fBis_constructible\fP< _Tp, _Up >, \fBis_assignable\fP< _Tp &, _Up >, __not_< __converts_from_optional< _Tp, _Up > >, __not_< __assigns_from_optional< _Tp, _Up > > >, \fBoptional\fP & > \fBoperator=\fP (\fBoptional\fP< _Up > &&__u) noexcept(__and_v< \fBis_nothrow_constructible\fP< _Tp, _Up >, \fBis_nothrow_assignable\fP< _Tp &, _Up > >)"
.br
.ti -1c
.RI "constexpr void \fBreset\fP () noexcept"
.br
.ti -1c
.RI "constexpr void \fBswap\fP (\fBoptional\fP &__other) noexcept(is_nothrow_move_constructible_v< _Tp > &&\fBis_nothrow_swappable_v\fP< _Tp >)"
.br
.ti -1c
.RI "constexpr _Tp & \fBvalue\fP () &"
.br
.ti -1c
.RI "constexpr _Tp && \fBvalue\fP () &&"
.br
.ti -1c
.RI "constexpr const _Tp & \fBvalue\fP () const &"
.br
.ti -1c
.RI "constexpr const _Tp && \fBvalue\fP () const &&"
.br
.ti -1c
.RI "template<typename _Up > constexpr _Tp \fBvalue_or\fP (_Up &&__u) &&"
.br
.ti -1c
.RI "template<typename _Up > constexpr _Tp \fBvalue_or\fP (_Up &&__u) const &"
.br
.in -1c
.SH "Detailed Description"
.PP 

.SS "template<typename _Tp>
.br
class std::optional< _Tp >"Class template for optional values\&. 
.PP
Definition at line \fB662\fP of file \fBoptional\fP\&.
.SH "Member Typedef Documentation"
.PP 
.SS "template<typename _Tp > using \fBstd::optional\fP< _Tp >::value_type =  _Tp"

.PP
Definition at line \fB692\fP of file \fBoptional\fP\&.
.SH "Constructor & Destructor Documentation"
.PP 
.SS "template<typename _Tp > constexpr \fBstd::optional\fP< _Tp >::optional ()\fC [inline]\fP, \fC [constexpr]\fP, \fC [noexcept]\fP"

.PP
Definition at line \fB694\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > constexpr \fBstd::optional\fP< _Tp >::optional (\fBnullopt_t\fP)\fC [inline]\fP, \fC [constexpr]\fP, \fC [noexcept]\fP"

.PP
Definition at line \fB696\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > template<typename _Up  = _Tp, _Requires< __not_self< _Up >, __not_tag< _Up >, \fBis_constructible\fP< _Tp, _Up >, \fBis_convertible\fP< _Up, _Tp > >  = true> constexpr \fBstd::optional\fP< _Tp >::optional (_Up && __t)\fC [inline]\fP, \fC [constexpr]\fP, \fC [noexcept]\fP"

.PP
Definition at line \fB704\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > template<typename _Up  = _Tp, _Requires< __not_self< _Up >, __not_tag< _Up >, \fBis_constructible\fP< _Tp, _Up >, __not_< \fBis_convertible\fP< _Up, _Tp > > >  = false> constexpr \fBstd::optional\fP< _Tp >::optional (_Up && __t)\fC [inline]\fP, \fC [explicit]\fP, \fC [constexpr]\fP, \fC [noexcept]\fP"

.PP
Definition at line \fB713\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > template<typename _Up , _Requires< __not_< \fBis_same\fP< _Tp, _Up > >, \fBis_constructible\fP< _Tp, const _Up & >, \fBis_convertible\fP< const _Up &, _Tp >, __not_< __converts_from_optional< _Tp, _Up > > >  = true> constexpr \fBstd::optional\fP< _Tp >::optional (const \fBoptional\fP< _Up > & __t)\fC [inline]\fP, \fC [constexpr]\fP, \fC [noexcept]\fP"

.PP
Definition at line \fB723\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > template<typename _Up , _Requires< __not_< \fBis_same\fP< _Tp, _Up > >, \fBis_constructible\fP< _Tp, const _Up & >, __not_< \fBis_convertible\fP< const _Up &, _Tp > >, __not_< __converts_from_optional< _Tp, _Up > > >  = false> constexpr \fBstd::optional\fP< _Tp >::optional (const \fBoptional\fP< _Up > & __t)\fC [inline]\fP, \fC [explicit]\fP, \fC [constexpr]\fP, \fC [noexcept]\fP"

.PP
Definition at line \fB736\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > template<typename _Up , _Requires< __not_< \fBis_same\fP< _Tp, _Up > >, \fBis_constructible\fP< _Tp, _Up >, \fBis_convertible\fP< _Up, _Tp >, __not_< __converts_from_optional< _Tp, _Up > > >  = true> constexpr \fBstd::optional\fP< _Tp >::optional (\fBoptional\fP< _Up > && __t)\fC [inline]\fP, \fC [constexpr]\fP, \fC [noexcept]\fP"

.PP
Definition at line \fB749\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > template<typename _Up , _Requires< __not_< \fBis_same\fP< _Tp, _Up > >, \fBis_constructible\fP< _Tp, _Up >, __not_< \fBis_convertible\fP< _Up, _Tp > >, __not_< __converts_from_optional< _Tp, _Up > > >  = false> constexpr \fBstd::optional\fP< _Tp >::optional (\fBoptional\fP< _Up > && __t)\fC [inline]\fP, \fC [explicit]\fP, \fC [constexpr]\fP, \fC [noexcept]\fP"

.PP
Definition at line \fB762\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > template<typename\&.\&.\&. _Args, _Requires< \fBis_constructible\fP< _Tp, _Args\&.\&.\&. > >  = false> constexpr \fBstd::optional\fP< _Tp >::optional (in_place_t, _Args &&\&.\&.\&. __args)\fC [inline]\fP, \fC [explicit]\fP, \fC [constexpr]\fP, \fC [noexcept]\fP"

.PP
Definition at line \fB772\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > template<typename _Up , typename\&.\&.\&. _Args, _Requires< \fBis_constructible\fP< _Tp, \fBinitializer_list\fP< _Up > &, _Args\&.\&.\&. > >  = false> constexpr \fBstd::optional\fP< _Tp >::optional (in_place_t, \fBinitializer_list\fP< _Up > __il, _Args &&\&.\&.\&. __args)\fC [inline]\fP, \fC [explicit]\fP, \fC [constexpr]\fP, \fC [noexcept]\fP"

.PP
Definition at line \fB781\fP of file \fBoptional\fP\&.
.SH "Member Function Documentation"
.PP 
.SS "template<typename _Tp > template<typename\&.\&.\&. _Args> constexpr \fBenable_if_t\fP< is_constructible_v< _Tp, _Args\&.\&.\&. >, _Tp & > \fBstd::optional\fP< _Tp >::emplace (_Args &&\&.\&.\&. __args)\fC [inline]\fP, \fC [constexpr]\fP, \fC [noexcept]\fP"

.PP
Definition at line \fB871\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > template<typename _Up , typename\&.\&.\&. _Args> constexpr \fBenable_if_t\fP< is_constructible_v< _Tp, \fBinitializer_list\fP< _Up > &, _Args\&.\&.\&. >, _Tp & > \fBstd::optional\fP< _Tp >::emplace (\fBinitializer_list\fP< _Up > __il, _Args &&\&.\&.\&. __args)\fC [inline]\fP, \fC [constexpr]\fP, \fC [noexcept]\fP"

.PP
Definition at line \fB883\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > constexpr bool \fBstd::optional\fP< _Tp >::has_value () const\fC [inline]\fP, \fC [constexpr]\fP, \fC [noexcept]\fP"

.PP
Definition at line \fB944\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > constexpr \fBstd::optional\fP< _Tp >::operator bool () const\fC [inline]\fP, \fC [explicit]\fP, \fC [constexpr]\fP, \fC [noexcept]\fP"

.PP
Definition at line \fB941\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > constexpr _Tp && \fBstd::optional\fP< _Tp >::operator* () &&\fC [inline]\fP, \fC [constexpr]\fP, \fC [noexcept]\fP"

.PP
Definition at line \fB934\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > constexpr _Tp & \fBstd::optional\fP< _Tp >::operator* () &\fC [inline]\fP, \fC [constexpr]\fP, \fC [noexcept]\fP"

.PP
Definition at line \fB930\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > constexpr const _Tp && \fBstd::optional\fP< _Tp >::operator* () const &&\fC [inline]\fP, \fC [constexpr]\fP, \fC [noexcept]\fP"

.PP
Definition at line \fB938\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > constexpr const _Tp & \fBstd::optional\fP< _Tp >::operator* () const &\fC [inline]\fP, \fC [constexpr]\fP, \fC [noexcept]\fP"

.PP
Definition at line \fB926\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > constexpr const _Tp * \fBstd::optional\fP< _Tp >::operator\-> () const\fC [inline]\fP, \fC [constexpr]\fP, \fC [noexcept]\fP"

.PP
Definition at line \fB918\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > constexpr _Tp * \fBstd::optional\fP< _Tp >::operator\-> ()\fC [inline]\fP, \fC [constexpr]\fP, \fC [noexcept]\fP"

.PP
Definition at line \fB922\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > template<typename _Up  = _Tp> constexpr \fBenable_if_t\fP< __and_v< __not_self< _Up >, __not_< __and_< \fBis_scalar\fP< _Tp >, \fBis_same\fP< _Tp, \fBdecay_t\fP< _Up > > > >, \fBis_constructible\fP< _Tp, _Up >, \fBis_assignable\fP< _Tp &, _Up > >, \fBoptional\fP & > \fBstd::optional\fP< _Tp >::operator= (_Up && __u)\fC [inline]\fP, \fC [constexpr]\fP, \fC [noexcept]\fP"

.PP
Definition at line \fB803\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > template<typename _Up > constexpr \fBenable_if_t\fP< __and_v< __not_< \fBis_same\fP< _Tp, _Up > >, \fBis_constructible\fP< _Tp, const _Up & >, \fBis_assignable\fP< _Tp &, const _Up & >, __not_< __converts_from_optional< _Tp, _Up > >, __not_< __assigns_from_optional< _Tp, _Up > > >, \fBoptional\fP & > \fBstd::optional\fP< _Tp >::operator= (const \fBoptional\fP< _Up > & __u)\fC [inline]\fP, \fC [constexpr]\fP, \fC [noexcept]\fP"

.PP
Definition at line \fB823\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > constexpr \fBoptional\fP & \fBstd::optional\fP< _Tp >::operator= (\fBnullopt_t\fP)\fC [inline]\fP, \fC [constexpr]\fP, \fC [noexcept]\fP"

.PP
Definition at line \fB789\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > template<typename _Up > constexpr \fBenable_if_t\fP< __and_v< __not_< \fBis_same\fP< _Tp, _Up > >, \fBis_constructible\fP< _Tp, _Up >, \fBis_assignable\fP< _Tp &, _Up >, __not_< __converts_from_optional< _Tp, _Up > >, __not_< __assigns_from_optional< _Tp, _Up > > >, \fBoptional\fP & > \fBstd::optional\fP< _Tp >::operator= (\fBoptional\fP< _Up > && __u)\fC [inline]\fP, \fC [constexpr]\fP, \fC [noexcept]\fP"

.PP
Definition at line \fB849\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > constexpr void \fBstd::optional\fP< _Tp >::reset ()\fC [inline]\fP, \fC [constexpr]\fP, \fC [noexcept]\fP"

.PP
Definition at line \fB1005\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > constexpr void \fBstd::optional\fP< _Tp >::swap (\fBoptional\fP< _Tp > & __other)\fC [inline]\fP, \fC [constexpr]\fP, \fC [noexcept]\fP"

.PP
Definition at line \fB896\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > constexpr _Tp & \fBstd::optional\fP< _Tp >::value () &\fC [inline]\fP, \fC [constexpr]\fP"

.PP
Definition at line \fB956\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > constexpr _Tp && \fBstd::optional\fP< _Tp >::value () &&\fC [inline]\fP, \fC [constexpr]\fP"

.PP
Definition at line \fB964\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > constexpr const _Tp & \fBstd::optional\fP< _Tp >::value () const &\fC [inline]\fP, \fC [constexpr]\fP"

.PP
Definition at line \fB948\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > constexpr const _Tp && \fBstd::optional\fP< _Tp >::value () const &&\fC [inline]\fP, \fC [constexpr]\fP"

.PP
Definition at line \fB972\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > template<typename _Up > constexpr _Tp \fBstd::optional\fP< _Tp >::value_or (_Up && __u) &&\fC [inline]\fP, \fC [constexpr]\fP"

.PP
Definition at line \fB994\fP of file \fBoptional\fP\&.
.SS "template<typename _Tp > template<typename _Up > constexpr _Tp \fBstd::optional\fP< _Tp >::value_or (_Up && __u) const &\fC [inline]\fP, \fC [constexpr]\fP"

.PP
Definition at line \fB981\fP of file \fBoptional\fP\&.

.SH "Author"
.PP 
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