std::ranges::elements_of

 

C++

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Feature test macros(C++20)

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Concepts library(C++20)

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Metaprogramming library(C++11)

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Ranges library(C++20)

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External libraries

 

Ranges library

Range access begin cbegin   end cend rbegin crbegin   rend crend size ssize   data cdata reserve_hint (C++26)   empty

Range conversions std::from_range_t std::from_range (C++23)(C++23)     to (C++23)

Dangling iterator handling dangling borrowed_iterator_t borrowed_subrange_t

Range primitives
range_size_trange_difference_trange_value_t elements_of (C++23)	iterator_tconst_iterator_tsentinel_tconst_sentinel_t (C++23)(C++23)	range_reference_trange_const_reference_trange_rvalue_reference_trange_common_reference_t (C++23)

Range concepts
range borrowed_range    common_range	sized_range viewable_range    view	input_range output_range forward_range	bidirectional_range    random_access_range contiguous_range	approximately_sized_range (C++26) constant_range (C++23)

Views
view_interface	subrange

Range factories
empty_viewviews::empty	single_viewviews::single	basic_istream_viewviews::istream	iota_viewviews::iota	repeat_viewviews::repeat (C++23)(C++23)

Range adaptors
views::all_tviews::all as_rvalue_viewviews::as_rvalue (C++23)(C++23)   filter_viewviews::filter transform_viewviews::transform take_viewviews::take take_while_viewviews::take_while common_viewviews::common views::counted to_input_viewviews::to_input (C++26)(C++26)	ref_view drop_viewviews::drop drop_while_viewviews::drop_while lazy_split_viewviews::lazy_split split_viewviews::split join_viewviews::join join_with_viewviews::join_with (C++23)(C++23)   concat_viewviews::concat (C++26)(C++26) cache_latest_viewviews::cache_latest (C++26)(C++26)	owning_view reverse_viewviews::reverse as_const_viewviews::as_const (C++23)(C++23) elements_viewviews::elements keys_viewviews::keys values_viewviews::values enumerate_viewviews::enumerate (C++23)(C++23) zip_viewviews::zip (C++23)(C++23) zip_transform_viewviews::zip_transform (C++23)(C++23)	adjacent_viewviews::adjacent (C++23)(C++23) views::pairwise (C++23) adjacent_transform_viewviews::adjacent_transform (C++23)(C++23) views::pairwise_transform (C++23) chunk_viewviews::chunk (C++23)(C++23) slide_viewviews::slide (C++23)(C++23) chunk_by_viewviews::chunk_by (C++23)(C++23) stride_viewviews::stride (C++23)(C++23) cartesian_product_viewviews::cartesian_product (C++23)(C++23)

Range generators std::generator (C++23)

Range adaptor closure objects range_adaptor_closure (C++23)

Range adaptor objects

Helper items
copyable-box movable-box (until C++23)  (C++23)	simple-view non-propagating-cache

 

Defined in header <ranges>
template<ranges::range R, class Allocator =std::allocator<std::byte>> struct elements_of;		(since C++23)

Encapsulates a range. Specializations of elements_of act as a tag in overload sets to disambiguate when a range should be treated as a sequence rather than a single value.

Template parameters

R	-	a type that satisfies range
Allocator	-	an allocator type that meets the requirements of Allocator

Data members

Member name	Definition
range	a range of type R (public member object)
allocator	an allocator of type Allocator. It has default member initializer that value initializes itself (public member object)

All these members are declared with [[no_unique_address]] attribute.

Deduction guide

template<class R, class Allocator =std::allocator<std::byte>> elements_of( R&&, Allocator = Allocator())-> elements_of<R&&, Allocator>;		(since C++23)

Example

Run this code

#include <any>#include <generator>#include <iostream>#include <ranges>#include <string_view>   template<bool Elementwise>std::generator<std::any> gen(std::ranges::input_rangeauto&& r){ifconstexpr(Elementwise) co_yield std::ranges::elements_of(r);// yield each element of relse co_yield r;// yield r as a single value}   int main(){auto test =std::string_view{"test"};   for(std::any a : gen<true>(test))std::cout<<'['<<std::any_cast<char>(a)<<"] ";std::cout<<'\n';   for(std::any a : gen<false>(test))std::cout<<'['<<std::any_cast<std::string_view>(a)<<"] ";std::cout<<'\n';}

Output:

[t] [e] [s] [t] [test]

References

• C++23 standard (ISO/IEC 14882:2024):

• 26.5.6 Class template elements_of [range.elementsof]