22 Iterators library [iterators]

22.5 Iterator adaptors [predef.iterators]

22.5.5 Default sentinels [default.sentinels]

namespace std { struct default_sentinel_t { }; }
Class default_­sentinel_­t is an empty 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., counted_­iterator ([counted.iterator])).