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

 

C++

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符號索引

外部庫

 

範圍庫 (Ranges library)

範圍訪問 begin cbegin   end cend rbegin crbegin   rend crend size ssize   data cdata reserve_hint (C++26)   empty

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

懸空迭代器處理 (Dangling iterator handling) dangling borrowed_iterator_t borrowed_subrange_t

範圍原語 (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)

範圍概念 (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)

檢視
view_interface	subrange

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

範圍介面卡 (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)

範圍生成器 (Range generators) std::generator (C++23)

範圍介面卡閉包物件 (Range adaptor closure objects) range_adaptor_closure (C++23)

範圍介面卡物件 (Range adaptor objects)

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

 

std::ranges::subrange

成員函式

subrange::subrange

subrange::operator PairLike

觀察器

subrange::begin

subrange::end

subrange::empty

subrange::size

迭代器操作

subrange::advance

subrange::next

subrange::prev

推導指引

非成員函式

get(std::ranges::subrange)

輔助型別

subrange_kind

tuple_size<std::ranges::subrange>

tuple_element<std::ranges::subrange>

 

定義於標頭檔案 <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> {};		(C++20 起)

此 std::ranges::subrange 的 std::tuple_size 偏特化提供了一種編譯時方式，以元組式語法獲取 subrange 的元件數量，其始終為 2。這為結構化繫結提供支援。

繼承自 std::integral_constant

成員常量

value [靜態]

常數值 2 (public static 成員常量)

成員函式

operator std::size_t	將物件轉換為 std::size_t，返回 value (公開成員函式)
operator() (C++14)	返回 value (公開成員函式)

成員型別

型別	定義
value_type	std::size_t
型別	std::integral_constant<std::size_t, value>

示例

執行此程式碼

#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";
}

輸出

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

參閱

結構化繫結 (C++17)	將指定的名稱繫結到初始化器的子物件或元組元素
tuple_size (C++11)	獲取類元組型別元素的數量 (類模板)
std::tuple_size<std::tuple> (C++11)	獲取 tuple 的大小 一個 tuple (類模板特化)
std::tuple_size<std::pair> (C++11)	獲取 pair 的大小 (類模板特化)
std::tuple_size<std::array> (C++11)	獲得 array 的大小 (類模板特化)
std::tuple_element<std::ranges::subrange> (C++20)	獲取 std::ranges::subrange 的迭代器或哨兵的型別 (類模板特化)