Editing Iterator (section)

==Pattern==
{{Main|Iterator pattern}}

An iterator provides access to an element of a collection (''element access'') and can change its internal state to provide access to the next element (''element traversal'').<ref name=ExternalInternal>{{cite web
 |url          = http://www.careerride.com/
 |title        = Difference between an external iterator and an internal iterator
 |date         = 2009-04-03
 |publisher    = CareerRide.COM
 |archive-url  = https://web.archive.org/web/20120919061643/http://careerride.com/
 |archive-date = 2012-09-19
 |quote        = An internal iterator is implemented by the member functions of the class which has the iteration logic. An external iterator is implemented by a separate class which can be attached to the object which has iteration logic. The advantage of external iterator is that, many iterators can be made active simultaneously on the existing or same object.
 |access-date  = 2012-08-08
 |url-status   = bot: unknown
}}</ref> It also provides for creation and initialization to a first element and indicates whether all elements have been traversed. In some programming contexts, an iterator provides additional functionality.

An iterator allows a consumer to process each element of a collection while isolating the consumer from the internal structure of the collection.<ref name=definition /> The collection can store elements in any manner while the consumer can access them as a sequence.

In object-oriented programming, an iterator class is usually designed in tight coordination with the corresponding collection class. Usually, the collection provides the methods for creating iterators.

A [[loop counter]] is sometimes also referred to as a loop iterator. A [[loop counter]], however, only provides the traversal functionality and not the element access functionality.