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std::default_sentinel_t, std::default_sentinel

From cppreference.com
< cpp‎ | iterator
 
 
Iterator library
Iterator concepts
Iterator primitives
Iterator adaptors
default_sentinel_tdefault_sentinel
(C++20)(C++20)
Stream iterators
Iterator customization points
Iterator operations
(C++11)
(C++11)
Range access
(C++11)(C++14)
(C++11)(C++14)
(C++17)(C++20)
(C++14)(C++14)
(C++14)(C++14)
(C++17)
(C++17)
 
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.

[edit] Example

#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

[edit] See also

iterator adaptor that tracks the distance to the end of the range
(class template) [edit]