std::experimental::optional< _Tp >(3) Library Functions Manual NAME std::experimental::optional< _Tp > - Class template for optional values. SYNOPSIS #include Inherits std::_Optional_base< _Tp, bool, bool >, and _Enable_copy_move< is_copy_constructible< _Tp >::value, __and_< is_copy_constructible< _Tp >, is_copy_assignable< _Tp > >::value, is_move_constructible< _Tp >::value, __and_< is_move_constructible< _Tp >, is_move_assignable< _Tp > >::value, optional< _Tp > >. Public Types using value_type Public Member Functions template, decay_t< _Up > > >, is_constructible< _Tp, _Up && >, is_convertible< _Up &&, _Tp > >::value, bool > = true> constexpr optional (_Up &&__t) template, decay_t< _Up > > >, is_constructible< _Tp, _Up && >, __not_< is_convertible< _Up &&, _Tp > > >::value, bool > = false> constexpr optional (_Up &&__t) template >, is_constructible< _Tp, const _Up & >, is_convertible< const _Up &, _Tp >, __not_< __converts_from_optional< _Tp, _Up > > >::value, bool > = true> constexpr optional (const optional< _Up > &__t) template >, is_constructible< _Tp, const _Up & >, __not_< is_convertible< const _Up &, _Tp > >, __not_< __converts_from_optional< _Tp, _Up > > >::value, bool > = false> constexpr optional (const optional< _Up > &__t) template >, is_constructible< _Tp, _Up && >, is_convertible< _Up &&, _Tp >, __not_< __converts_from_optional< _Tp, _Up > > >::value, bool > = true> constexpr optional (optional< _Up > &&__t) template >, is_constructible< _Tp, _Up && >, __not_< is_convertible< _Up &&, _Tp > >, __not_< __converts_from_optional< _Tp, _Up > > >::value, bool > = false> constexpr optional (optional< _Up > &&__t) template enable_if_t< is_constructible< _Tp, _Args &&... >::value > emplace (_Args &&... __args) template enable_if_t< is_constructible< _Tp, initializer_list< _Up > &, _Args &&... >::value > emplace (initializer_list< _Up > __il, _Args &&... __args) constexpr operator bool () const noexcept constexpr _Tp & operator* () & constexpr _Tp && operator* () && constexpr const _Tp & operator* () const & constexpr const _Tp && operator* () const && _Tp * operator-> () constexpr const _Tp * operator-> () const template enable_if_t< __and_< __not_< is_same< optional< _Tp >, decay_t< _Up > > >, is_constructible< _Tp, _Up >, __not_< __and_< is_scalar< _Tp >, is_same< _Tp, decay_t< _Up > > > >, is_assignable< _Tp &, _Up > >::value, optional & > operator= (_Up &&__u) template enable_if_t< __and_< __not_< is_same< _Tp, _Up > >, is_constructible< _Tp, const _Up & >, is_assignable< _Tp &, _Up >, __not_< __converts_from_optional< _Tp, _Up > >, __not_< __assigns_from_optional< _Tp, _Up > > >::value, optional & > operator= (const optional< _Up > &__u) optional & operator= (nullopt_t) noexcept template enable_if_t< __and_< __not_< is_same< _Tp, _Up > >, is_constructible< _Tp, _Up >, is_assignable< _Tp &, _Up >, __not_< __converts_from_optional< _Tp, _Up > >, __not_< __assigns_from_optional< _Tp, _Up > > >::value, optional & > operator= (optional< _Up > &&__u) void swap (optional &__other) noexcept(is_nothrow_move_constructible< _Tp >() &&__is_nothrow_swappable< _Tp >::value) constexpr _Tp & value () & constexpr _Tp && value () && constexpr const _Tp & value () const & constexpr const _Tp && value () const && template _Tp value_or (_Up &&__u) && template constexpr _Tp value_or (_Up &&__u) const & Detailed Description template class std::experimental::optional< _Tp >"Class template for optional values. Author Generated automatically by Doxygen for libstdc++ from the source code. libstdc++ std::experimental::optional< _Tp >(3)