Editing For loop (section)

{{Short description|Control flow statement for repeated execution}}
[[File:For loop example.svg|thumb|right|Flow diagram of the following for loop code:
<syntaxhighlight lang="c">
for (i = 0; i < 5; i++)
  printf("*");
</syntaxhighlight>

The loop will cause five asterisks to be printed.]]
{{Loop constructs}}<!-- DO NOT remove. Discuss navigation concept at [[Talk:Do while loop#Helpbox experiment]] -->

In [[computer science]], a '''for-loop''' or '''for loop''' is a [[control flow]] [[Statement (computer science)|statement]] for specifying [[iteration]]. Specifically, a for-loop functions by running a section of code repeatedly until a certain condition has been satisfied.

For-loops have two parts: a header and a body. The header defines the iteration and the body is the code executed once per iteration. The header often declares an explicit [[For loop#Loop counters|loop counter]] or loop [[Variable (computer science)|variable]]. This allows the body to know which iteration is being executed. For-loops are typically used when the number of iterations is known before entering the loop. For-loops can be thought of as shorthands for [[while-loop]]s which increment and test a loop variable.

Various keywords are used to indicate the usage of a for loop: descendants of [[ALGOL]] use "{{mono|for}}", while descendants of [[Fortran]] use "{{mono|do}}". There are other possibilities, for example [[COBOL]] which uses {{nowrap|{{code|PERFORM VARYING}}}}.

The name ''for-loop'' comes from the word [[Wiktionary: for|for]]. ''For'' is used as the [[reserved word]] (or keyword) in many programming languages to introduce a for-loop. The term in English dates to [[ALGOL 58]] and was popularized in [[ALGOL 60]]. It is the direct translation of the earlier German {{Wikt-lang|de|für}} and was used in [[Superplan]] (1949–1951) by [[Heinz Rutishauser]]. Rutishauser was involved in defining ALGOL 58 and ALGOL 60.<ref>{{Cite book |last=Wirth |first=Niklaus |author-link=Niklaus Wirth |year=1973 |chapter=Preface |title=Systematic Programming: An Introduction |pages=xiii |publisher=Prentice-Hall |isbn=0138803692}}</ref> The loop body is executed "for" the given values of the loop variable. This is more explicit in [[ALGOL]] versions of the for statement where a list of possible values and increments can be specified.

In Fortran and [[PL/I]], the keyword {{mono|DO}} is used for the same thing and it is named a ''do-loop''; this is different from a ''[[do while loop]]''.