std::ranges::adjacent_view<V,N>::size

 

C++

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自立实现与有宿主实现

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标准库标头

具名要求

功能特性测试宏 (C++20)

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概念库 (C++20)

元编程库 (C++11)

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通用工具库

字符串库

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范围库 (C++20)

算法库

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文件系统库 (C++17)

正则表达式库 (C++11)

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符号索引

外部库

 

范围库

范围访问
begin cbegin end cend	rbegin crbegin rend crend	size ssize data cdata	empty
范围转换器
to (C++23)
范围原语
range_size_trange_difference_t range_value_t	range_reference_trange_const_reference_trange_rvalue_reference_t (C++23)	iterator_tconst_iterator_tsentinel_t (C++23)
悬垂迭代器处理
dangling	borrowed_iterator_t	borrowed_subrange_t
范围概念
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
视图
view_interface	subrange
范围工厂
empty_viewviews::empty single_viewviews::single	iota_viewviews::iota repeat_viewviews::repeat (C++23)(C++23)	basic_istream_viewviews::istream cartesian_product_viewviews::cartesian_product_view (C++23)(C++23)
适配器
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)
范围生成器
std::generator (C++23)
范围适配器对象
范围适配器闭包对象
range_adaptor_closure (C++23)
辅助项
copyable-box	simple-view

 

std::ranges::adjacent_view

成员函数

adjacent_view::adjacent_view (C++23)

adjacent_view::begin (C++23)

adjacent_view::end (C++23)

adjacent_view::size (C++23)

迭代器

成员函数

adjacent_view::iterator::iterator (C++23)

adjacent_view::iterator::operator* (C++23)

adjacent_view::iterator::operator[] (C++23)

adjacent_view::iterator::operator++ adjacent_view::iterator::operator++(int) adjacent_view::iterator::operator-- adjacent_view::iterator::operator--(int) adjacent_view::iterator::operator+= adjacent_view::iterator::operator-= (C++23)(C++23)(C++23)(C++23)(C++23)(C++23)

非成员函数

operator==(adjacent_view::iterator) operator<(adjacent_view::iterator) operator>(adjacent_view::iterator) operator<=(adjacent_view::iterator) operator>=(adjacent_view::iterator) operator<=>(adjacent_view::iterator) (C++23)(C++23)(C++23)(C++23)(C++23)(C++23)

operator+(adjacent_view::iterator) operator-(adjacent_view::iterator) (C++23)(C++23)

iter_move(adjacent_view::iterator) (C++23)

iter_swap(adjacent_view::iterator) (C++23)

哨兵

成员函数

adjacent_view::sentinel::sentinel (C++23)

非成员函数

operator==(adjacent_view::iterator,adjacent_view::sentinel) (C++23)

operator-(adjacent_view::iterator,adjacent_view::sentinel) (C++23)

 

constexpr auto size() requires ranges::sized_range<V>;		(C++23 起)
constexpr auto size() const requires ranges::sized_range<const V>;		(C++23 起)

返回元素的数量。

令 base_ 为底层视图。等价于：

using SizeType = decltype(ranges::size(base_));
using CommonType = ranges::common_type_t<SizeType, std::size_t>;
auto size = static_cast<CommonType>(ranges::size(base_));
size -= std::min<CommonType>(size, N - 1);
return static_cast<SizeType>(size);

参数

(无)

返回值

元素的数量，ranges::size(base_) 小于 N 值可能为 ​0​。

示例

运行此代码

#include <ranges>
 
int main()
{
    constexpr static auto v = {1, 2, 3, 4, 5, 6};
 
    constexpr int width1 {4};
    constexpr auto view1 {std::views::adjacent<width1>(v)};
    static_assert(view1.size() == 3);
    static_assert(view1.size() == (v.size() - width1 + 1));
 
    constexpr int width2 {8};
    constexpr auto view2 {std::views::adjacent<width2>(v)};
    // 窗口太窄，所以视图无元素。
    static_assert(view2.size() == 0);
}

参阅

ranges::size (C++20)	返回等于范围大小的整数 (定制点对象)
ranges::ssize (C++20)	返回等于范围大小的有符号整数 (定制点对象)