View source for Loop (computing)

In [[computing]], a '''loop''' is a [[sequence]] of [[Statement (computer science)|statements]] which is specified once but which may be carried out several times in succession.

== Description ==

The code "inside" the loop (the ''body'' of the loop, shown below as ''xxx'') is obeyed a specified number of times, or once for each of a collection of items, or until some condition is met, or [[infinite loop|indefinitely]].

In [[functional programming]] languages, such as [[Haskell (programming language)|Haskell]] and [[Scheme (programming language)|Scheme]], loops can be expressed by using [[recursion (computer science)|recursion]] or [[fixed point combinator|fixed point iteration]] rather than explicit looping constructs. [[Tail recursion]] is a special case of recursion which can be easily transformed to iteration.

== Examples ==

Various types of loop exist:

* Count-controlled loops
* Condition-controlled loops
* Collection-controlled loops
* General iteration
* Infinite loops
* Continuation with next iteration
* Redo current iteration
* Restart loop
* Early exit from loops
* Loop variants and invariants

== See also ==

* [[Computing]]
* [[Control flow]]
* [[Statement (computer science)]]

== External links == 

* [https://en.wikipedia.org/wiki/Control_flow#Loops Control flow: Loops] @ Wikipedia

[[Category:Computer programming]]
[[Category:Computer science]]
[[Category:Computing]]