Editing Iterator (section)

===Classification===

====Categories====

Iterators can be categorised according to their functionality. Here is a (non-exhaustive) list of iterator categories:<ref>{{cite web
 | url        = http://www.phpro.org/tutorials/Introduction-to-SPL.html#2
 | title      = C++ Iteratoren: Iterator-Kategorien
 | author     = Kevin Waterson
 | language   = de
 | publisher  = cppreference.com
 | access-date = 2012-08-09
}}</ref><ref>{{cite web
 | url        = http://www.sgi.com/tech/stl/Iterators.html
 | title      = Iterators: Concepts
 | author     = Kevin Waterson
 | publisher  = sgi
 | access-date = 2012-08-09
}}</ref>

{| class="wikitable sortable"
|-
! Category !! Languages
|-
| Bidirectional iterator || [[C++]], [[Rust (programming language)|Rust]]<ref>{{cite web |title=DoubleEndedIterator in std::iter - Rust |url=https://doc.rust-lang.org/std/iter/trait.DoubleEndedIterator.html |website=doc.rust-lang.org |access-date=11 May 2025}}</ref>
|-
| Forward iterator || C++
|-
| Input iterator || C++
|-
| Output iterator || C++
|-
| Random access iterator || C++
|-
| Trivial iterator || C++ (old [[Standard Template Library|STL]])<ref>{{cite web
 |url          = https://stackoverflow.com/
 |title        = Types of iterator: Output vs. input vs. forward vs. random access iterator
 |author       = larsmans
 |date         = 2011-03-06
 |publisher    = stackoverflow
 |archive-url  = https://web.archive.org/web/20120808230608/http://stackoverflow.com/
 |archive-date = 2012-08-08
 |access-date  = 2012-08-09
 |url-status   = bot: unknown
}}</ref>
|}

====Types====
Different languages or libraries used with these languages define iterator types. Some of them are<ref>{{cite web
 | url        = http://www.phpro.org/tutorials/Introduction-to-SPL.html#2
 | title      = Introduction to SPL: Introduction to Standard PHP Library (SPL)
 | author     = Kevin Waterson
 | publisher  = PHPRO.ORG
 | access-date = 2012-08-09
}}</ref>

{| class="wikitable sortable"
|-
! Type !! Languages
|-
| Array iterator || [[PHP]], R<ref>{{cite web|last=Collier|first=Andrew|title=Iterators in R|url=http://www.exegetic.biz/blog/2013/11/iterators-in-r/|access-date=16 November 2013|archive-date=18 October 2018|archive-url=https://web.archive.org/web/20181018084806/http://www.exegetic.biz/blog/2013/11/iterators-in-r/|url-status=dead}}</ref> 
|-
| Caching iterator || PHP
|-
| Constant iterator || [[C++]],<ref>{{cite web
 | url      = http://threadingbuildingblocks.org/docs/help/reference/containers_overview/concurrent_unordered_set_cls.htm
 | title      = concurrent_unordered_set Template Class
 | publisher      = Intel Threading Building Blocks for Open Source
 | quote      = •The iterator types iterator and const_iterator are of the forward iterator category
 | access-date      = 2012-08-09
 | archive-url      = https://web.archive.org/web/20150501163238/http://threadingbuildingblocks.org/docs/help/reference/containers_overview/concurrent_unordered_set_cls.htm
 | archive-date      = 2015-05-01
 | url-status      = dead
 }}</ref> PHP
|-
| Directory iterator || PHP, [[Python (programming language)|Python]]
|-
| Filter iterator || PHP, R
|-
| Limit iterator || PHP
|-
| List iterator || [[C Sharp (programming language)|C#]], [[Java (programming language)|Java]],<ref name=HFDPIterators /> R
|-
| Recursive array iterator || PHP
|-
| XML iterator || PHP
|}