std::tuple_size<std:ranges::subrange>

 

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Ranges library

Range access
begin cbegin end cend	rbegin crbegin rend crend	size ssize data cdata	empty
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to (C++23)
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range_size_trange_difference_trange_value_trange_reference_t	iterator_tconst_iterator_tsentinel_tconst_sentinel_t (C++23)(C++23)	range_const_reference_trange_rvalue_reference_trange_common_reference_t (C++23)	elements_of (C++23)
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dangling	borrowed_iterator_t	borrowed_subrange_t
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range borrowed_range sized_range constant_range (C++23)	common_range view viewable_range	input_range output_range forward_range	bidirectional_range random_access_range contiguous_range
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view_interface	subrange
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empty_viewviews::empty single_viewviews::single	iota_viewviews::iota repeat_viewviews::repeat (C++23)(C++23)	basic_istream_viewviews::istream
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views::all_tviews::all ref_view owning_view as_rvalue_viewviews::as_rvalue (C++23)(C++23) filter_viewviews::filter transform_viewviews::transform take_viewviews::take take_while_viewviews::take_while	drop_viewviews::drop drop_while_viewviews::drop_while join_viewviews::join join_with_viewviews::join_with (C++23)(C++23) lazy_split_viewviews::lazy_split split_viewviews::split views::counted common_viewviews::common	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)
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std::generator (C++23)
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range_adaptor_closure (C++23)
Helper items
copyable-box movable-box (until C++23)(C++23)	simple-view non-propagating-cache

 

std::ranges::subrange

Member functions

subrange::subrange (C++20)

subrange::operator PairLike (C++20)

Observers

subrange::begin (C++20)

subrange::end (C++20)

subrange::empty (C++20)

subrange::size (C++20)

Iterator operations

subrange::advance (C++20)

subrange::next (C++20)

subrange::prev (C++20)

Deduction guides

Non-member functions

get (C++20)

Helper types

subrange_kind (C++20)

tuple_size (C++20)

tuple_element (C++20)

 

Defined in header <ranges>
template< class I, class S, ranges::subrange_kind K > struct tuple_size<ranges::subrange<I, S, K>>     : std::integral_constant<std::size_t, 2> {};		(since C++20)

The partial specialization of std::tuple_size for std::ranges::subrange provides a compile-time way to obtain the number of components of a subrange, which is always 2, using tuple-like syntax. It is provided for structured binding support.

Inherited from std::integral_constant

Member constants

value [static]

the constant value 2 (public static member constant)

Member functions

operator std::size_t	converts the object to std::size_t, returns value (public member function)
operator() (C++14)	returns value (public member function)

Member types

Type	Definition
value_type	std::size_t
type	std::integral_constant<std::size_t, value>

Example

Run this code

#include <array>
#include <iostream>
#include <iterator>
#include <ranges>
 
int main()
{
    static_assert(2 == std::tuple_size_v<std::ranges::subrange<int*, int*>>);
 
    using array5 = std::array<int, 5>;
 
    static_assert(2 == std::tuple_size<std::ranges::subrange<
        array5::const_iterator, array5::const_iterator>>{});
 
    constexpr array5 a{ 1, 2, 3, 4, 5 };
 
    std::ranges::subrange sub_a1{a};
 
    for (std::cout << "sub_a1: { "; int e : sub_a1) { std::cout << e << ' '; }
    std::cout << "}\n";
 
    std::ranges::subrange sub_a2{std::next(cbegin(a)), std::prev(cend(a))};
 
    const auto [first, last] = sub_a2;
    std::cout << "sub_a2 size = " << std::distance(first, last) << '\n';
 
    for (std::cout << "sub_a2: { "; int e : sub_a2) { std::cout << e << ' '; }
    std::cout << "}\n";
}

Output:

sub_a1: { 1 2 3 4 5 }
sub_a2 size = 3
sub_a2: { 2 3 4 }

See also

Structured binding (C++17)	binds the specified names to sub-objects or tuple elements of the initializer
tuple_size (C++11)	obtains the number of elements of a tuple-like type (class template)
std::tuple_element<std::ranges::subrange> (C++20)	obtains the type of the iterator or the sentinel of a std::ranges::subrange (class template specialization)