23 Iterators library [iterators]

The template parameter Iterator shall either meet the Cpp17InputIterator requirements ([input.iterators]) or model input_­iterator ([iterator.concept.input]).

Additionally, if any of the bidirectional traversal functions are instantiated, the template parameter shall either meet the Cpp17BidirectionalIterator requirements ([bidirectional.iterators]) or model bidirectional_­iterator ([iterator.concept.bidir]).

If any of the random access traversal functions are instantiated, the template parameter shall either meet the Cpp17RandomAccessIterator requirements ([random.access.iterators]) or model random_­access_­iterator ([iterator.concept.random.access]).