std::ranges::elements_view<V,F>::iterator<Const>::operator*

 

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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 (until C++23)  (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

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)

 

constexpr decltype(auto) operator*() const;		(C++20 起)

返回底层迭代器指向的 V 中的元素。

等效地返回 /*get-element*/(this->base())，其中对于表达式 e，/*get-element*/(e) 为

• std::get<N>(*e)，如果 ranges::range_reference_t<Base> 是引用类型。否则，
• static_cast<E>(std::get<N>(*e))，其中 E 为 std::remove_cv_t<std::tuple_element_t<N, ranges::range_reference_t<Base>>>。

参数

(无)

返回值

当前元素。

注释

operator-> 未提供。

示例

运行此代码

#include <iostream>
#include <ranges>
#include <string_view>
#include <tuple>
 
int main()
{
    using T = std::tuple<int, char, std::string_view>;
 
    const auto il = {
        T{1, 'A', "α"},
        T{2, 'B', "β"},
        T{3, 'C', "γ"},
    };
 
    const auto view {il | std::views::elements<2>};
 
    const auto iter {view.begin() + 1};
 
    std::cout << *iter << '\n';
}

输出

β

参见

operator[] (C++20)

通过索引访问元素 (公共成员函数)