std::default_sentinel_t, std::default_sentinel

Defined in header <iterator>
struct default_sentinel_t { };
(1) (since C++20)
inline constexpr default_sentinel_t default_sentinel{};
(2) (since C++20)
1) default_sentinel_t is an empty class type used to denote the end of a range. It can be used together with iterator types that know the bound of their range (e.g., std::counted_iterator).
2) default_sentinel is a constant of type default_sentinel_t.


#include <iterator>
#include <algorithm>
#include <list>
#include <iostream>
int main()
    std::list<int> l{3,1,4,1,5,9,2,6};
    std::ranges::copy(std::counted_iterator(std::begin(l), 4),
        std::default_sentinel, std::ostream_iterator<int>{std::cout, " "});


3 1 4 1

See also

input iterator that reads from std::basic_istream
(class template)
input iterator that reads from std::basic_streambuf
(class template)
iterator adaptor that tracks the distance to the end of the range
(class template)

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