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) input_or_output_iterator (C++20) sentinel_for (C++20) sized_sentinel_for (C++20)	input_iterator (C++20) 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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indirect_result_t (C++20)	projected (C++20)
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reverse_iterator move_iterator (C++11) 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) back_insert_iterator front_insert_iterator insert_iterator	make_reverse_iterator (C++14) make_move_iterator (C++11) default_sentinel_tdefault_sentinel (C++20)(C++20) unreachable_sentinel_tunreachable_sentinel (C++20)(C++20) make_const_iterator (C++23) make_const_sentinel (C++23) back_inserter front_inserter inserter
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istream_iterator ostream_iterator	istreambuf_iterator ostreambuf_iterator
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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

Run this code

#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, " "});
}

Output:

3 1 4 1

See also

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)