std::default_sentinel_t, std::default_sentinel

 

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indirectly_readable (C++20) indirectly_writable (C++20) weakly_incrementable (C++20) incrementable (C++20) is-integer-like is-signed-integer-like (C++20)(C++20)	sentinel_for (C++20) sized_sentinel_for (C++20) input_iterator (C++20) output_iterator (C++20) input_or_output_iterator (C++20)	forward_iterator (C++20) bidirectional_iterator (C++20) random_access_iterator (C++20) contiguous_iterator (C++20)
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input_iterator_tagoutput_iterator_tagforward_iterator_tagbidirectional_iterator_tagrandom_access_iterator_tagcontiguous_iterator_tag (C++20)	iter_value_titer_difference_titer_reference_titer_const_reference_titer_rvalue_reference_titer_common_reference_t (C++20)(C++20)(C++20)(C++23)(C++20)(C++20)	iterator (C++17 弃用) iterator_traits incrementable_traits (C++20) indirectly_readable_traits (C++20)
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indirectly_unary_invocableindirectly_regular_unary_invocable (C++20)(C++20)	indirect_unary_predicate (C++20) indirect_binary_predicate (C++20)	indirect_equivalence_relation (C++20) indirect_strict_weak_order (C++20)
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indirectly_movable (C++20) indirectly_movable_storable (C++20) indirectly_copyable (C++20)	indirectly_copyable_storable (C++20)   indirectly_swappable (C++20) indirectly_comparable (C++20)	permutable (C++20) mergeable (C++20) sortable (C++20)
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indirect_result_t (C++20)	projected (C++20)	projected_value_t (C++26)
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reverse_iterator make_reverse_iterator (C++14) move_iterator (C++11) make_move_iterator (C++11) default_sentinel_tdefault_sentinel (C++20)(C++20) unreachable_sentinel_tunreachable_sentinel (C++20)(C++20)	front_insert_iterator back_insert_iterator inserter insert_iterator front_inserter back_inserter move_sentinel (C++20)	common_iterator (C++20) counted_iterator (C++20) basic_const_iterator (C++23) const_iterator (C++23) const_sentinel (C++23) make_const_iterator (C++23) make_const_sentinel (C++23)
流迭代器 istream_iterator    ostream_iterator istreambuf_iterator ostreambuf_iterator	迭代器定制点 ranges::iter_move (C++20) ranges::iter_swap (C++20)
迭代器操作 advance distance prev (C++11)   next (C++11) ranges::advance (C++20) ranges::distance (C++20) ranges::prev (C++20) ranges::next (C++20)	范围访问 begincbegin (C++11)(C++14) rbegincrbegin (C++14)(C++14)   endcend (C++11)(C++14) rendcrend (C++14)(C++14)   sizessize (C++17)(C++20) empty (C++17) data (C++17)

 

在标头 <iterator> 定义
struct default_sentinel_t {};	(1)	(C++20 起)
inlineconstexpr default_sentinel_t default_sentinel{};	(2)	(C++20 起)

1)default_sentinel_t 是用于表示范围结尾的空类类型。能与知晓其范围边界的迭代器类型（例如 std::counted_iterator）一同使用它。

2)default_sentinel 是 default_sentinel_t 类型常量。

示例

运行此代码

#include <print>#include <regex>#include <string>   int main(){conststd::string s ="Quick brown fox.";   conststd::regex words_regex("[^\\s]+");const std::ranges::subrange words(std::sregex_iterator(s.begin(), s.end(), words_regex), std::default_sentinel);   std::println("找到 {} 个单词：", std::ranges::distance(words));for(conststd::smatch& match : words)std::println("{}", match.str());}

输出：

找到 3 个单词： Quick brown fox.

参阅

istream_iterator	从 std::basic_istream 读取的输入迭代器 (类模板)
istreambuf_iterator	从 std::basic_streambuf 读取的输入迭代器 (类模板)
counted_iterator (C++20)	对到范围结尾距离进行跟踪的迭代器适配器 (类模板)