std:: projected_value_t

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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)
output_iterator (C++20)
input_or_output_iterator (C++20)

forward_iterator (C++20)
bidirectional_iterator (C++20)
random_access_iterator (C++20)
contiguous_iterator (C++20)

Iterator primitives

input_iterator_tag output_iterator_tag forward_iterator_tag bidirectional_iterator_tag random_access_iterator_tag contiguous_iterator_tag

(C++20)

iter_value_t iter_difference_t iter_reference_t iter_const_reference_t iter_rvalue_reference_t iter_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_invocable indirectly_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_t default_sentinel (C++20) (C++20)
unreachable_sentinel_t unreachable_sentinel (C++20) (C++20)

front_insert_iterator
back_insert_iterator
inserter
insert_iterator
front_inserter
back_inserter
move_sentinel (C++20)

common_iterator (C++20)
counted_iterator (C++20)
basic_const_iterator (C++23)
const_iterator (C++23)
const_sentinel (C++23)
make_const_iterator (C++23)
make_const_sentinel (C++23)

Stream iterators

istream_iterator
ostream_iterator

istreambuf_iterator
ostreambuf_iterator

Iterator customization points
ranges::iter_move (C++20)
ranges::iter_swap (C++20)

Iterator operations

advance
distance
prev (C++11)
next (C++11)

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

Range access

begin cbegin (C++11) (C++14)
rbegin crbegin (C++14) (C++14)

end cend (C++11) (C++14)
rend crend (C++14) (C++14)

size ssize (C++17) (C++20)
empty (C++17)
data (C++17)

定義先ヘッダ `<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 > & >> ;		(C++26以降)

エイリアステンプレート projected_value_t は、 Proj を std:: iter_value_t < I > & に適用した結果の型から、参照と最上位のCV修飾子を取り除くことで値型を取得します。

projected_value_t は、 ranges:: contains などの一部のアルゴリズムにおいてデフォルト値の型を決定するために使用されます。

Compiler support
Freestanding and hosted
Language
Standard library
Standard library headers
Named requirements
Feature test macros (C++20)
Language support library
Concepts library (C++20)
Diagnostics library
Memory management library
Metaprogramming library (C++11)
General utilities library
Containers library
Iterators library
Ranges library (C++20)
Algorithms library
Strings library
Text processing library
Numerics library
Date and time library
Input/output library
Filesystem library (C++17)
Concurrency support library (C++11)
Execution control library (C++26)
Technical specifications
Symbols index
External libraries

cppreference.net

Namespaces

Variants

std:: projected_value_t

目次

テンプレートパラメータ

注記

例

関連項目

I	-	間接的に読み取り可能な型
Proj	-	`I` の値型への左辺値参照に適用される射影

indirect_result_t (C++20)	間接的に読み取り可能な型の集合をデリファレンスした結果に対して呼び出し可能オブジェクトを呼び出した結果を計算する (エイリアステンプレート)
projected (C++20)	射影を受け入れるアルゴリズムの制約を指定するためのヘルパーテンプレート (エイリアステンプレート)