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std:: default_sentinel_t, std:: default_sentinel

From cppreference.net
C++
Iterator library
Iterator concepts
Iterator primitives
Algorithm concepts and utilities
Indirect callable concepts
Common algorithm requirements
(C++20)
(C++20)
(C++20)
Utilities
(C++20)
Iterator adaptors
(C++14)
(C++11)
(C++11)
default_sentinel_t default_sentinel
(C++20) (C++20)
(C++20) (C++20)
Range access
(C++11) (C++14)
(C++14) (C++14)
(C++11) (C++14)
(C++14) (C++14)
(C++17) (C++20)
(C++17)
(C++17)
定义于头文件 <iterator>
struct default_sentinel_t { } ;
(1) (C++20 起)
inline constexpr default_sentinel_t default_sentinel { } ;
(2) (C++20 起)
1) default_sentinel_t 是一个空类类型，用于表示范围的终点。它可以与知晓自身范围边界的迭代器类型（例如 std::counted_iterator ）配合使用。
2) default_sentinel 是一个类型为 default_sentinel_t 的常量。

示例

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

输出： 

Found 3 words:
Quick
brown
fox.

参见

从 std::basic_istream 读取的输入迭代器
(类模板)
从 std::basic_streambuf 读取的输入迭代器
(类模板)
(C++20)
跟踪到范围末尾距离的迭代器适配器
(类模板)