std::indirect_result_t

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[edit]

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)
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_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
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

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)

[edit]

Defined in header`<iterator>`
template<class F,class...Is> requires(std::indirectly_readable<Is>&& ...)&& std::invocable<F,std::iter_reference_t<Is>...> using indirect_result_t=std::invoke_result_t<F,std::iter_reference_t<Is>...>;		(since C++20)

The alias templateindirect_result_t obtains the result type of invoking aninvocable typeF on the result of dereferencingindirectly_readable typesIs....

[edit]Template parameters

F	-	an invocable type
Is	-	indirectly readable types that are dereferenced to arguments

[edit]Example

Run this code

#include <iterator>#include <type_traits> struct Fn{long operator()(constint&);int operator()(int&&);short operator()(int,int)const;auto operator()(constfloat)->int&;void operator()(int[8]);}; static_assert(std::is_same_v<std::indirect_result_t<Fn,constint*>,long> andstd::is_same_v<std::indirect_result_t<Fn,std::move_iterator<int*>>,int> andstd::is_same_v<std::indirect_result_t<const Fn,int*,int*>,short> andstd::is_same_v<std::indirect_result_t<Fn,float*>,int&> andstd::is_same_v<std::indirect_result_t<Fn,int**>,void>); int main(){}

[edit]See also

result_ofinvoke_result (C++11)(removed in C++20)(C++17)	deduces the result type of invoking a callable object with a set of arguments (class template)[edit]
projected_value_t (C++26)	computes the value type of an`indirectly_readable` type by projection (alias template)[edit]

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std::indirect_result_t

[edit]Template parameters

[edit]Example

[edit]See also

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