std::ranges::concat_view<Views...>::begin

 

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) sized-random-access-range (C++26)

视图
view_interface	subrange

范围工厂
empty_viewviews::empty	single_viewviews::single	basic_istream_viewviews::istream	iota_viewviews::iota views::indices (C++26)	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 as_input_viewviews::as_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::concat_view

成员函数

concat_view::concat_view

concat_view::begin

concat_view::end

concat_view::size

推导指引

迭代器

成员函数

concat_view::iterator::iterator

concat_view::iterator::operator*

concat_view::iterator::operator[]

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

concat_view::iterator::satisfy concat_view::iterator::prev concat_view::iterator::advance-fwd concat_view::iterator::advance-bwd

非成员函数

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

operator+(concat_view::iterator) operator-(concat_view::iterator)

iter_move(concat_view::iterator)

iter_swap(concat_view::iterator)

 

constexpr /*iterator*/<false> begin() requires (!(/*simple-view*/<Views> && ...));	(1)	(C++26 起)
constexpr /*iterator*/<true> begin() const requires (ranges::range<const Views> && ...) && /*concatable*/<const Views...>;	(2)	(C++26 起)

返回指向 concat_view 开头的迭代器。

1) 等价于

iterator <false> it(this, std::in_place_index<0>,
                  ranges::begin(std::get<0>(views_ )));
it.template satisfy <0>();
return it;

2) 等价于

iterator <true> it(this, std::in_place_index<0>,
                 ranges::begin(std::get<0>(views_ )));
it.template satisfy <0>();
return it;

返回值

如上所述。

示例

运行此代码

#include <print>
#include <ranges>
#include <string_view>
using namespace std::literals;

int main()
{
    static constexpr auto c = {"🐱", "🐶"};
    static constexpr auto a = {"🤡"sv};
    static constexpr auto t = {"💚"sv};
    static constexpr auto cat{std::views::concat(c, a, t)};
    static_assert(*cat.begin() == "\U0001F431" and
                  cat.begin()[1] == "🐶" and
                  *(cat.begin() + 2) == "\N{CLOWN FACE}");
    std::println("{}", cat);
}

输出：

["🐱", "🐶", "🤡", "💚"]

参阅

end	返回 指向末尾的迭代器或哨位 (公开成员函数)
ranges::begin (C++20)	返回指向范围起始的迭代器 (定制点对象)