9 Iterators library [iterators]

9.3 Iterator requirements [iterator.requirements]

9.3.8 Concept Iterator [iterators.iterator]

The Iterator concept forms the basis of the iterator concept taxonomy; every iterator satisfies the Iterator requirements. This concept specifies operations for dereferencing and incrementing an iterator. Most algorithms will require additional operations to compare iterators with sentinels ([iterators.sentinel]), to read ([iterators.input]) or write ([iterators.output]) values, or to provide a richer set of iterator movements ([iterators.forward], [iterators.bidirectional], [iterators.random.access]).)

  template <class I>
  concept bool Iterator =
    requires(I i) {
      { *i } -> auto&&; // Requires: i is dereferenceable
    } &&

Note: The requirement that the result of dereferencing the iterator is deducible from auto&& means that it cannot be void. — end note ]