.TH "std::optional< _Tp >" 3cxx "Wed Jul 28 2021" "libstdc++" \" -*- nroff -*-
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.SH NAME
std::optional< _Tp > \- Class template for optional values\&.  

.SH SYNOPSIS
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.PP
.PP
Inherits \fBstd::_Optional_base< _Tp, bool, bool >\fP, and \fBstd::_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 > >\fP\&.
.SS "Public Types"

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.RI "using \fBvalue_type\fP = _Tp"
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.SS "Public Member Functions"

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.RI "template<typename _Up  = _Tp, _Requires< __not_self< _Up >, __not_tag< _Up >, is_constructible< _Tp, _Up >, is_convertible< _Up, _Tp >>  = true> constexpr \fBoptional\fP (_Up &&__t) noexcept(is_nothrow_constructible_v< _Tp, _Up >)"
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.RI "template<typename _Up  = _Tp, _Requires< __not_self< _Up >, __not_tag< _Up >, is_constructible< _Tp, _Up >, __not_< is_convertible< _Up, _Tp >>>  = false> constexpr \fBoptional\fP (_Up &&__t) noexcept(is_nothrow_constructible_v< _Tp, _Up >)"
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.RI "template<typename _Up , _Requires< __not_< is_same< _Tp, _Up >>, is_constructible< _Tp, const _Up & >, is_convertible< 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 & >)"
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.RI "template<typename _Up , _Requires< __not_< is_same< _Tp, _Up >>, is_constructible< _Tp, const _Up & >, __not_< is_convertible< 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 & >)"
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.RI "template<typename\&.\&.\&. _Args, _Requires< is_constructible< _Tp, _Args\&.\&.\&. >>  = false> constexpr \fBoptional\fP (in_place_t, _Args &&\&.\&.\&. __args) noexcept(is_nothrow_constructible_v< _Tp, _Args\&.\&.\&. >)"
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.RI "template<typename _Up , typename\&.\&.\&. _Args, _Requires< is_constructible< _Tp, initializer_list< _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\&.\&.\&. >)"
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.RI "constexpr \fBoptional\fP (\fBnullopt_t\fP) noexcept"
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.RI "template<typename _Up , _Requires< __not_< is_same< _Tp, _Up >>, is_constructible< _Tp, _Up >, is_convertible< _Up, _Tp >, __not_< __converts_from_optional< _Tp, _Up >>>  = true> constexpr \fBoptional\fP (\fBoptional\fP< _Up > &&__t) noexcept(is_nothrow_constructible_v< _Tp, _Up >)"
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.RI "template<typename _Up , _Requires< __not_< is_same< _Tp, _Up >>, is_constructible< _Tp, _Up >, __not_< is_convertible< _Up, _Tp >>, __not_< __converts_from_optional< _Tp, _Up >>>  = false> constexpr \fBoptional\fP (\fBoptional\fP< _Up > &&__t) noexcept(is_nothrow_constructible_v< _Tp, _Up >)"
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.RI "template<typename\&.\&.\&. _Args> \fBenable_if_t\fP< is_constructible_v< _Tp, _Args\&.\&.\&. >, _Tp & > \fBemplace\fP (_Args &&\&.\&.\&. __args) noexcept(is_nothrow_constructible_v< _Tp, _Args\&.\&.\&. >)"
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.RI "template<typename _Up , typename\&.\&.\&. _Args> \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"
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.RI "constexpr _Tp & \fBoperator*\fP () &noexcept"
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.RI "constexpr const _Tp && \fBoperator*\fP () const &&noexcept"
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.RI "constexpr const _Tp & \fBoperator*\fP () const &noexcept"
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.RI "constexpr const _Tp * \fBoperator\->\fP () const noexcept"
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.RI "constexpr _Tp * \fBoperator\->\fP () noexcept"
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.RI "template<typename _Up  = _Tp> \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 >>)"
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.RI "template<typename _Up > \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 & >>)"
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.RI "\fBoptional\fP & \fBoperator=\fP (\fBnullopt_t\fP) noexcept"
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.RI "template<typename _Up > \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 >>)"
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.RI "void \fBreset\fP () noexcept"
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.RI "void \fBswap\fP (\fBoptional\fP &__other) noexcept(is_nothrow_move_constructible_v< _Tp > &&\fBis_nothrow_swappable_v\fP< _Tp >)"
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.RI "constexpr _Tp & \fBvalue\fP () &"
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.RI "constexpr _Tp && \fBvalue\fP () &&"
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.RI "constexpr const _Tp & \fBvalue\fP () const &"
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.RI "constexpr const _Tp && \fBvalue\fP () const &&"
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.RI "template<typename _Up > constexpr _Tp \fBvalue_or\fP (_Up &&__u) &&"
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.RI "template<typename _Up > constexpr _Tp \fBvalue_or\fP (_Up &&__u) const &"
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.SH "Detailed Description"
.PP 

.SS "template<typename _Tp>
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class std::optional< _Tp >"
Class template for optional values\&. 
.PP
Definition at line 663 of file optional\&.

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