< cpp‎ | experimental‎ | ranges
Technical specifications
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template < class S, class I >

concept bool Sentinel =
  Semiregular<S> && Iterator<I> &&

  WeaklyEqualityComparableWith<S, I>;
(ranges TS)

The Sentinel concept specifies the relationship between an Iterator type and a Semiregular type whose values denote a range.

Let s and i be values of type S and I, respectively, such that [i, s) denotes a range. Sentinel<S, I> is satisfied only if:

  • i == s is well-defined.
  • If bool(i != s) then i is dereferenceable and [++i, s) denotes a range.

The domain of == can change over time. Given an iterator i and sentinel s such that [i, s) denotes a range and i != s, [i, s) is not required to continue to denote a range after incrementing any iterator equal to i (and so i == s is no longer required to be well-defined after such an increment).