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.

Example

#include <algorithm>
#include <iostream>
#include <iterator>
#include <list>
 
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, " "});
    std::cout << '\n';
}

Output:

3 1 4 1

istream_iterator	input iterator that reads from `std::basic_istream` (class template)
istreambuf_iterator	input iterator that reads from `std::basic_streambuf` (class template)
counted_iterator (C++20)	iterator adaptor that tracks the distance to the end of the range (class template)

std::default_sentinel_t, std::default_sentinel

Example

See also