std::ranges::elements_view<V,N>::elements_view

 

C++

编译器支持

自立实现与有宿主实现

语言

标准库

标准库标头

具名要求

功能特性测试宏 (C++20)

语言支持库

概念库 (C++20)

诊断库

内存管理库

元编程库 (C++11)

通用工具库

容器库

迭代器库

范围库 (C++20)

算法库

字符串库

文本处理库

数值库

日期和时间库

输入/输出库

文件系统库 (C++17)

并发支持库 (C++11)

执行控制库 (C++26)

技术规范

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 reserve_hint (C++26)   empty

范围转换 std::from_range_t std::from_range (C++23)(C++23)     to (C++23)

悬垂迭代器处理 dangling borrowed_iterator_t borrowed_subrange_t

范围原语
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)

范围概念
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)

视图
view_interface	subrange

范围工厂
empty_viewviews::empty	single_viewviews::single	basic_istream_viewviews::istream	iota_viewviews::iota	repeat_viewviews::repeat (C++23)(C++23)

范围适配器
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)

范围生成器 std::generator (C++23)

范围适配器闭包对象 range_adaptor_closure (C++23)

范围适配器对象

辅助项
copyable-box movable-box (C++23 前)  (C++23)	simple-view non-propagating-cache

 

std::ranges::elements_view

成员函数

elements_view::elements_view

elements_view::base

elements_view::begin

elements_view::end

elements_view::size

elements_view::reserve_hint (C++26)

嵌套类

迭代器

elements_view::iterator::iterator

elements_view::iterator::base

elements_view::iterator::operator*

elements_view::iterator::operator[]

elements_view::iterator::operator++ elements_view::iterator::operator++(int) elements_view::iterator::operator-- elements_view::iterator::operator--(int) elements_view::iterator::operator+= elements_view::iterator::operator-=

operator==(elements_view::iterator) operator<(elements_view::iterator) operator>(elements_view::iterator) operator<=(elements_view::iterator) operator>=(elements_view::iterator) operator<=>(elements_view::iterator)

operator+(elements_view::iterator) operator-(elements_view::iterator)

哨位

elements_view::sentinel::sentinel

elements_view::sentinel::base

operator==(elements_view::iterator,elements_view::sentinel)

operator-(elements_view::iterator,elements_view::sentinel)

 

elements_view() requires std::default_initializable<V> = default;	(1)	(C++20 起)
constexpr explicit elements_view( V base );	(2)	(C++20 起)

构造 elements_view。

1) 默认构造函数。值初始化底层视图 base_。构造后 base() 返回 V() 的副本。

2) 以 std::move(base) 初始化底层视图 base_。

参数

base

-

底层视图

示例

运行此代码

#include <array>
#include <iostream>
#include <ranges>
#include <tuple>

void println(auto const& v)
{
    for (auto const& e : v)
        std::cout << e << ' ';
    std::cout << '\n';
}

int main()
{
    using namespace std::literals;

    const std::array<std::tuple<int, char, std::string>, 2> vt
    {
        std::tuple{1, 'A', "α"s},
        std::tuple{2, 'B', "β"s},
    };

    [[maybe_unused]]
    auto empty = std::views::elements<0>;

    println(std::views::elements<0>(vt));
    println(std::views::elements<1>(vt));
    println(std::views::elements<2>(vt));
}

输出：

1 2
A B
α β