std::projected_value_t

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Iterator library

Iterator concepts

indirectly_readable (C++20)
indirectly_writable (C++20)
weakly_incrementable (C++20)
incrementable (C++20)
is-integer-like is-signed-integer-like (C++20)(C++20)

sentinel_for (C++20)
sized_sentinel_for (C++20)
input_iterator (C++20)
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forward_iterator (C++20)
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Iterator primitives

input_iterator_tagoutput_iterator_tagforward_iterator_tagbidirectional_iterator_tagrandom_access_iterator_tagcontiguous_iterator_tag

(C++20)

iter_value_titer_difference_titer_reference_titer_const_reference_titer_rvalue_reference_titer_common_reference_t

(C++20)(C++20)(C++20)(C++23)(C++20)(C++20)

iterator (deprecated in C++17)
iterator_traits
incrementable_traits (C++20)
indirectly_readable_traits (C++20)

Algorithm concepts and utilities

Indirect callable concepts

indirectly_unary_invocableindirectly_regular_unary_invocable

(C++20)(C++20)

indirect_unary_predicate (C++20)
indirect_binary_predicate (C++20)

indirect_equivalence_relation (C++20)
indirect_strict_weak_order (C++20)

Common algorithm requirements

indirectly_movable (C++20)
indirectly_movable_storable (C++20)
indirectly_copyable (C++20)

indirectly_copyable_storable (C++20)
indirectly_swappable (C++20)
indirectly_comparable (C++20)

permutable (C++20)
mergeable (C++20)
sortable (C++20)

Utilities

indirect_result_t

(C++20)

projected

(C++20)

projected_value_t

(C++26)

Iterator adaptors

reverse_iterator
make_reverse_iterator (C++14)
move_iterator (C++11)
make_move_iterator (C++11)
default_sentinel_tdefault_sentinel (C++20)(C++20)
unreachable_sentinel_tunreachable_sentinel (C++20)(C++20)

front_insert_iterator
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advance
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next (C++11)

ranges::advance (C++20)
ranges::distance (C++20)
ranges::prev (C++20)
ranges::next (C++20)

Range access

begincbegin (C++11)(C++14)
rbegincrbegin (C++14)(C++14)

endcend (C++11)(C++14)
rendcrend (C++14)(C++14)

sizessize (C++17)(C++20)
empty (C++17)
data (C++17)

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Defined in header`<iterator>`
template<std::indirectly_readable I, std::indirectly_regular_unary_invocable<I> Proj> using projected_value_t= std::remove_cvref_t<std::invoke_result_t<Proj&,std::iter_value_t<I>&>>;		(since C++26)

The alias templateprojected_value_t obtains the value type by stripping any reference and its topmost cv-qualifiers of the result type of applyingProj tostd::iter_value_t<I>&.

projected_value_t is used to determine the default value type in some algorithms such asranges::contains.

[edit]Template parameters

I	-	an indirectly readable type
Proj	-	projection applied to an lvalue reference to value type of`I`

[edit]Notes

Feature-test macro	Value	Std	Feature
`__cpp_lib_algorithm_default_value_type`	`202403L`	(C++26)	default template type for algorithm values using`std::projected_value_t`

[edit]Example

This section is incomplete
Reason: no example

[edit]See also

indirect_result_t (C++20)	computes the result of invoking a callable object on the result of dereferencing some set of`indirectly_readable` types (alias template)[edit]
projected (C++20)	helper template for specifying the constraints on algorithms that accept projections (alias template)[edit]