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This means it might contain formatting issues, incorrect code, conceptual problems, or other severe issues.

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{{task|Iteration}} Loop through and print each element in a collection in order.

Use your language's "for each" loop if it has one, otherwise iterate through the collection in order with some other loop.

;Related tasks:

  • [[Loop over multiple arrays simultaneously]]
  • [[Loops/Break]]
  • [[Loops/Continue]]
  • [[Loops/Do-while]]
  • [[Loops/Downward for]]
  • [[Loops/For]]
  • [[Loops/For with a specified step]]
  • [[Loops/Foreach]]
  • [[Loops/Increment loop index within loop body]]
  • [[Loops/Infinite]]
  • [[Loops/N plus one half]]
  • [[Loops/Nested]]
  • [[Loops/While]]
  • [[Loops/with multiple ranges]]
  • [[Loops/Wrong ranges]]

ACL2

(defun print-list (xs)
   (if (endp xs)
       nil
       (prog2$ (cw "~x0~%" (first xs))
               (print-list (rest xs)))))


> (print-list (list 1 "a" 1/2 (list 1 2) 'sym))
1
"a"
1/2
(1 2)
SYM
NIL

Ada

arrays

with Ada.Integer_Text_IO;
use  Ada.Integer_Text_IO;

procedure For_Each is

   A : array (1..5) of Integer := (-1, 0, 1, 2, 3);

begin

   for Num in A'Range loop
      Put( A (Num) );
   end loop;

end For_Each;

Alternative solution (Ada 2012):

   for Item of A loop
      Put( Item );
   end loop;

doubly linked lists

{{works with|Ada 2005}}

with Ada.Integer_Text_IO, Ada.Containers.Doubly_Linked_Lists;
use  Ada.Integer_Text_IO, Ada.Containers;

procedure Doubly_Linked_List is

   package DL_List_Pkg is new Doubly_Linked_Lists (Integer);
   use     DL_List_Pkg;

   procedure Print_Node (Position : Cursor) is
   begin
      Put (Element (Position));
   end Print_Node;

   DL_List : List;

begin

   DL_List.Append (1);
   DL_List.Append (2);
   DL_List.Append (3);

   -- Iterates through every node of the list.
   DL_List.Iterate (Print_Node'Access);

end Doubly_Linked_List;

vectors

{{works with|Ada 2005}}

with Ada.Integer_Text_IO, Ada.Containers.Vectors;
use  Ada.Integer_Text_IO, Ada.Containers;

procedure Vector_Example is

   package Vector_Pkg is new Vectors (Natural, Integer);
   use     Vector_Pkg;

   procedure Print_Element (Position : Cursor) is
   begin
      Put (Element (Position));
   end Print_Element;

   V : Vector;

begin

   V.Append (1);
   V.Append (2);
   V.Append (3);

   -- Iterates through every element of the vector.
   V.Iterate (Print_Element'Access);

end Vector_Example;

Aikido

Aikido's foreach loop allows iteration through multiple value types.

strings

var str = "hello world"
foreach ch str {    // you can also use an optional 'in'
    println (ch)   // one character at a time
}

vectors

var vec = [1,2,3,4]
foreach v vec {    // you can also use an optional 'in'
    println (v)
}

maps

var cities = {"San Ramon": 50000, "Walnut Creek": 70000, "San Francisco": 700000}   // map literal
foreach city cities {
    println (city.first + " has population " + city.second)
}

integers

foreach i 100 {
    println (i)    // prints values 0..99
}

foreach i 10..20 {
    println (i)     // prints values 10..20
}

var a = 20
var b = 10
foreach i a..b {
    println (i)   // prints values from a to b (20..10)
}

Objects

Aikido allows definition of a foreach operator for an object. In this example we define a single linked list and a foreach operator to iterate through it

class List {
    class Element (public data) {
        public var next = null
    }
    var start = null

    public function insert (data) {
        var element = new Element (data)
        element.next = start
        start = element
    }

    public operator foreach (var iter) {
        if (typeof(iter) == "none") {   // first iteration
            iter = start
            return iter.data
        } elif (iter.next == null) {    // check for last iteration
            iter = none
        } else {
            iter = iter.next      // somewhere in the middle
            return iter.data
        }
    }

}

var list = new List()
list.insert (1)
list.insert (2)
list.insert (4)

foreach n list {
    println (n)
}

Coroutines

Aikido supports coroutines. The foreach operator may be used to iterate thorough the generated values.

// coroutine to generate the squares of a sequence of numbers
function squares (start, end) {
    for (var i = start ; i < end ; i++) {
        yield i*i
    }
}

var start = 10
var end = 20

foreach s squares (start, end) {
    println (s)
}

Files

If you open a file you can iterate through all the lines

var s = openin ("input.txt")
foreach line s {
    print (line)
}

Enumerations

enum Color {
   RED, GREEN, BLUE
}

foreach color Color {
    println (color)
}

Aime

# iterate over a list of integers
integer i, v;

for (i, v in list(2, 3, 5, 7, 11, 13, 17, 18)) {
}

ALGOL 68

{{works with|ALGOL 68|Standard - no extensions to language used}} {{works with|ALGOL 68G|Any - tested with release mk15-0.8b.fc9.i386}} {{works with|ELLA ALGOL 68|Any (with appropriate job cards) - tested with release 1.8.8d.fc9.i386}}

[]UNION(STRING, INT, PROC(REF FILE)VOID) collection = ("Mary","Had",1,"little","lamb.",new line);

FOR index FROM LWB collection TO UPB collection DO
  print((collection[index]," "))
OD

Output:


Mary Had          +1 little lamb.

Note: [[ALGOL 68S]] actually has a reserved word FOREACH that is used to break arrays in to portions, and process in parallel.

AmigaE

PROC main()
  DEF a_list : PTR TO LONG, a
  a_list := [10, 12, 14]
  FOR a := 0 TO ListLen(a_list)-1
    WriteF('\d\n', a_list[a])
  ENDFOR
  -> if the "action" fits a single statement, we can do instead
  ForAll({a}, a_list, `WriteF('\d\n', a))
ENDPROC

Apex


Integer[] myInts = new Integer[]{1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

for (Integer i : myInts) {
    System.debug(i);
}

AppleScript

repeat with fruit in {"Apple", "Orange", "Banana"}
  log contents of fruit
end repeat

Arturo

array #("one" "two" "three")

dict #{
	name	"john"
	surname	"doe"
	age	33
}

loop array {
	print &
}

loop dict [key,val]{
	print key + " => " + val
}

{{out}}

one
two
three
surname => doe
age => 33
name => john

AutoHotkey

string = mary,had,a,little,lamb
Loop, Parse, string, `,
  MsgBox %A_LoopField%

AWK

The for (element_index in array) can be used, but it does not give elements' indexes in the order inside the array (AWK indexes in array are indeed more like hashes).


BEGIN {
  split("Mary had a little lamb", strs, " ")
  for(el in strs) {
    print strs[el]
  }
}

If elements must be returned in some order, keys must be generated in that order. In the example above the array is filled through the split function, which uses indexes from 1. So to iterate over the array's elements in the ''right'' order, a normal loop can be used:

BEGIN {
  n = split("Mary had a little lamb", strs, " ")
  for(i=1; i <= n; i++) {
    print strs[i]
  }
}

Note that in awk, foreach loops can only be performed against an associative container. It is not possible to loop against an explicit list, so the following will not work:

# This will not work
BEGIN {
  for (l in "apples","bananas","cherries") {
  print "I like " l
}

BASIC

=

BASIC256

= BASIC-256 does not have a FOR EACH type statement. Use a FOR loop to iterate through an array by index.

DIM collection$(1)
collection$ = { "The", "quick", "brown", "fox", "jumps", "over", "the", "lazy", "dog." }

FOR i = 0 TO collection$[?]-1
   PRINT collection$[i]+ " ";
NEXT i
PRINT

Output:

The quick brown fox jumps over the lazy dog.

=

BBC BASIC

= {{works with|BBC BASIC for Windows}}

      DIM collection$(8)
      collection$() = "The", "quick", "brown", "fox", "jumps", \
      \               "over", "the", "lazy", "dog."

      FOR index% = 0 TO DIM(collection$(), 1)
        PRINT collection$(index%) " ";
      NEXT
      PRINT

=

Commodore BASIC

= Commodore BASIC too does not have a FOR-EACH construct. FOR loop is used to iterate through a string array by index. READ-DATA is used to fill up the string array

10 DIM A$(9) :REM DECLARE STRING ARRAY
20 REM *** FILL ARRAY WITH WORDS ***
30 FOR I = 0 TO 8
40 READ A$(I)
50 NEXT
60 REM *** PRINT ARRAY CONTENTS ***
70 FOR I = 0 TO 8
80 PRINT A$(I)" ";
90 NEXT
100 END
1000 DATA THE, QUICK, BROWN, FOX, JUMPS, OVER, THE, LAZY, DOG.

=

Creative Basic

=

DEF AnArray[11]:INT

AnArray=0,1,2,3,4,5,6,7,8,9,10

'A console only program will work without OPENCONSOLE and
'CLOSECONSOLE; however, it does not hurt to use them.
OPENCONSOLE

FOR X=0 TO 10
    PRINT AnArray[X]
NEXT X

'keep the console from closing right away.
DO:UNTIL INKEY$<>""

CLOSECONSOLE

'because this is a console only program.
END

=

FreeBASIC

=

' FB 1.05.0

' FreeBASIC doesn't have a foreach loop but it's easy to manufacture one using macros

#Macro ForEach(I, A)
For _i as integer = LBound(A) To UBound(A)
#Define I (A(_i))
#EndMacro

#Define In ,

Dim a(-5 To 5) As Integer = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}
ForEach(i in a)
  Print i; " ";
Next

Print
Sleep

{{out}}


 1  2  3  4  5  6  7  8  9  10  11

=

Gambas

= '''[https://gambas-playground.proko.eu/?gist=cb94500c68749f6f93915f3f10de5a03 Click this link to run this code]'''

Public Sub Main()
Dim siInput As Short[] = [1, 8, 0, 6, 4, 7, 3, 2, 5, 9]
Dim siTemp As Short

For Each siTemp In siInput.Sort()
  Print siTemp;;
Next

End

{{out}}


0 1 2 3 4 5 6 7 8 9

==={{header|IS-BASIC}}=== 100 STRING COLLECTION$(1 TO 9)*8 110 LET I=1 120 DO 130 READ IF MISSING EXIT DO:COLLECTION$(I) 140 LET I=I+1 150 LOOP 160 FOR J=1 TO I-1 170 PRINT COLLECTION$(J);" "; 180 NEXT 190 DATA The,quick,brown,fox,jumps,over,the,lazy,dog.



=
## IWBASIC
=
'''Linked List'''

```IWBASIC
DEF AList:POINTER

AList=ListCreate()

'Add items to the list.
DEF X:INT

FOR X=0 TO 10
    POINTER Temp=ListAdd(AList,NEW(INT,1))
    #<INT>temp=X
'The hash ("#") dereferencing operator is unique to IWBASIC and Creative Basic, and
'it is suitable for most basic pointer needs. IWBASIC also supports a "C style"
'dereferencing operator: "*". And that will work here too.
NEXT X

'A program compiled as console only does not need the commands to open and
'close the console. However, it does not hurt to use them.
OPENCONSOLE

'***Iterate the list with the "for each" loop***
FOR Temp=EACH AList AS INT
     PRINT #Temp
NEXT

PRINT

'A press any key to continue message is automatic in a program compiled as a console only
program. I presume the compiler inserts the code.
CLOSECONSOLE

'Because this is a console only program.
END

'''An Array'''

DEF AnArray[11]:INT

AnArray=0,1,2,3,4,5,6,7,8,9,10

OPENCONSOLE

FOR X=0 TO 10
	PRINT AnArray[X]
NEXT X

PRINT

'a press any key message is automatic when compiled as console only.
CLOSECONSOLE

'Because this is a console only program.
END

=

Liberty BASIC

= The most natural way is to use a csv list with a sentinel value.

in$      ="Not,Hardly,Just,Adequately,Quite,Really,Very,Fantastically,xyzzy"
element$ =""
i =1    '   used to point to successive elements

do
    element$ =word$( in$, i, ",")
    if element$ ="xyzzy" then exit do
    print element$; " good!"
    i =i +1
loop until 1 =2

end

Not good! Hardly good! Just good! Adequately good! Quite good! Really good! Very good! Fantastically good!

==={{header|NS-HUBASIC}}=== 10 DIM A$(9) : REM DECLARE STRING ARRAY 20 REM ADD DATA TO ARRAY AND PRINT ARRAY CONTENTS 30 FOR I=0 TO 8 40 READ A$(I) 50 PRINT A$(I)" "; 60 NEXT 70 DATA THE, QUICK, BROWN, FOX, JUMPS, OVER, THE, LAZY, DOG.



=
## PureBasic
=
Works for LinkedLists and Maps

```PureBasic
ForEach element()
  PrintN(element())
Next

=

Run BASIC

=

t$={Sunday,Monday,Tuesday,Wednesday,Thursday,Friday,Saturday"

while word$(t$,i+1,",") <> ""
  i = i + 1
  print word$(t$,i,",")
wend

==={{header|TI-89 BASIC}}===

Local i,strs
Define strs = {"Lorem","ipsum","dolor"}
For i, 1, dim(strs)
  Disp strs[i]
EndFor

=

VBA

=

Public Sub LoopsForeach()
    Dim FruitArray() As Variant
    Dim Fruit As Variant
    FruitArray = [{"Apple","Banana","Strawberry"}]
    Dim FruitBasket As Collection
    Set FruitBasket = New Collection
    For Each Fruit In FruitArray
        FruitBasket.Add Fruit
    Next Fruit
    For Each Fruit In FruitBasket
        Debug.Print Fruit
    Next Fruit
End Sub

=

VBScript

=

items = Array("Apple", "Orange", "Banana")

For Each x In items
    WScript.Echo x
Next

=

Visual Basic .NET

=

Dim list As New List(Of String)
list.Add("Car")
list.Add("Boat")
list.Add("Train")

For Each item In list
    Console.WriteLine(item)
Next

Batch File

The FOR command can imitate the "Foreach Loop". The whitespace and the comma (,) are the default delimiters.

'''Direct usage:'''

@echo off
for %%A in (This is a sample collection) do (
     echo %%A
)

'''Using a Collection Variable:'''

@echo off
set "collection=This is a sample collection"
for %%A in (%collection%) do (
     echo %%A
)

{{Out|They have the Same Output}}

This
is
a
sample
collection

bc

There is no "for each"-loop in bc. For accessing each element of an array (the only collection-like type) one uses a straightforward for-loop.

a[0] = .123
a[1] = 234
a[3] = 95.6
for (i = 0; i < 4; i++) {
    a[i]
}

Bracmat

Bracmat has a more or less traditional 'while' loop (whl'expression) which was introduced rather late in the history of Bracmat. Before that, tail recursion was a way to repeat something. But let us make a list first:

  ( list
  =   Afrikaans
      Ελληνικά
      עברית
      മലയാളം
      ئۇيغۇرچە
  )

The 'while' solution. Use an auxiliary variable L that gets its head chopped off until nothing is left:

  !list:?L
& whl'(!L:%?language ?L&out$!language)

The tail-recursive solution. When the auxiliary variable is reduced to nothing, the loop fails. By adding the ~ flag to the initial invocation, failure is turned into success. This solution benefits from tail recursion optimization.

  !list:?L
& ( loop
  =   !L:%?language ?L
    & out$!language
    & !loop
  )
& ~!loop

A completely different way of iteration is by using a pattern that matches an element in the list, does something useful as a side effect and then fails, forcing bracmat to backtrack and try the next element in the list. The @ flag matches at most one element. The % flag matches at least one element. Together they ensure that exactly one language name is assigned to the variable language. After all elements have been done, control is passed to the rhs of the | operator.

  (   !list
    : ? (%@?language&out$!language&~) ?
  |
  )

C

C does not really have a native 'container' type, nor does it have a 'for each' type statement. The following shows how to loop through an array and print each element.

#include <stdio.h>
...

const char *list[] = {"Red","Green","Blue","Black","White"};
#define LIST_SIZE (sizeof(list)/sizeof(list[0]))

int ix;
for(ix=0; ix<LIST_SIZE; ix++) {
   printf("%s\n", list[ix]);
}

The C language does, however, have a number of standard data structures that can be thought of as collections, and foreach can easily be made with a macro.

C string as a collection of char


#include <stdio.h>
#include <stdlib.h>
/* foreach macro for using a string as a collection of char */
#define foreach( ptrvar , strvar ) char* ptrvar; for( ptrvar=strvar ; (*ptrvar) != '\0' ; *ptrvar++)

int main(int argc,char* argv[]){
char* s1="abcdefg";
char* s2="123456789";
foreach( p1 , s1 ) {
 printf("loop 1 %c\n",*p1);
}
foreach( p2 , s2 ){
 printf("loop 2 %c\n",*p2);
}
exit(0);
return(0);
}

C int array as a collection of int (array size known at compile-time)


#include <stdio.h>
#include <stdlib.h>
int main(int argc,char* argv[]){
/* foreach macro viewing an array of int values as a collection of int values */
#define foreach( intpvar , intary ) int* intpvar; for( intpvar=intary; intpvar < (intary+(sizeof(intary)/sizeof(intary[0]))) ; intpvar++)
int a1[]={ 1 , 1 , 2 , 3 , 5 , 8 };
int a2[]={ 3 , 1 , 4 , 1, 5, 9 };
foreach( p1 , a1 ) {
 printf("loop 1 %d\n",*p1);
}
foreach( p2 , a2 ){
 printf("loop 2 %d\n",*p2);
}
exit(0);
return(0);
}

Most general: string or array as collection (collection size known at run-time) : ''Note: idxtype can be removed and [http://gcc.gnu.org/onlinedocs/gcc/Typeof.html typeof(col[0])] can be used in it's place with [[GCC]]''


#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(int argc,char* argv[]){
#define foreach( idxtype , idxpvar , col , colsiz ) idxtype* idxpvar; for( idxpvar=col ; idxpvar < (col+(colsiz)) ; idxpvar++)
#define arraylen( ary ) ( sizeof(ary)/sizeof(ary[0]) )
char* c1="collection";
int c2[]={ 3 , 1 , 4 , 1, 5, 9 };
double* c3;
int c3len=4;
c3=(double*)calloc(c3len,sizeof(double));
c3[0]=1.2;c3[1]=3.4;c3[2]=5.6;c3[3]=7.8;
foreach( char,p1   , c1, strlen(c1) ) {
 printf("loop 1 : %c\n",*p1);
}
foreach( int,p2    , c2, arraylen(c2) ){
 printf("loop 2 : %d\n",*p2);
}
foreach( double,p3 , c3, c3len ){
 printf("loop 3 : %3.1lf\n",*p3);
}
exit(0);
return(0);
}

C++

C++03 did not have a "for each" loop. The following is a generic loop which works with any standard container except for built-in arrays. The code snippet below assumes that the container type in question is typedef'd to container_type and the actual container object is named container.

for (container_type::iterator i = container.begin(); i != container.end(); ++i)
{
  std::cout << *i << "\n";
}

However the idiomatic way to output a container would be

std::copy(container.begin(), container.end(),
          std::ostream_iterator<container_type::value_type>(std::cout, "\n"));

There's also an algorithm named for_each. However, you need a function or function object to use it, e.g.

void print_element(container_type::value_type const& v)
{
  std::cout << v << "\n";
}

...
  std::for_each(container.begin(), container.end(), print_element);

{{works with|C++11}}

for (auto element: container)
{
  std::cout << element << "\n";
}

Here container is the container variable, element is the loop variable (initialized with each container element in turn), and auto means that the compiler should determine the correct type of that variable automatically. If the type is expensive to copy, a const reference can be used instead:

for (auto const& element: container)
{
  std::cout << element << "\n";
}

Of course the container elements can also be changed by using a non-const reference (provided the container isn't itself constant):

for (auto&& element: container) //use a 'universal reference'
{
  element += 42;
}

C#

string[] things = {"Apple", "Banana", "Coconut"};

foreach (string thing in things)
{
    Console.WriteLine(thing);
}

Chapel

var food = ["Milk", "Bread", "Butter"];
for f in food do writeln(f);

Clojure

(doseq [item collection] (println item))

CMake

set(list one.c two.c three.c)

foreach(file ${list})
  message(${file})
endforeach(file)

COBOL

The following is in the Managed COBOL dialect: {{trans|C#}} {{works with|Visual COBOL}}

01  things occurs 3.
...
set content of things to ("Apple", "Banana", "Coconut")
perform varying thing as string through things
    display thing
end-perform

ColdFusion


<Cfloop list="Fee, Fi, Foe, Fum" index="i">
  <Cfoutput>#i#!</Cfoutput>
</Cfloop>

Common Lisp

(loop for i in list do (print i))

or

(map nil #'print list)

D

This works if ''collection'' is a string/array/associative array, or if implements an appropriate ''opApply'' function, or if it has the basic Range methods.

import std.stdio: writeln;

void main() {
    auto collection1 = "ABC";
    foreach (element; collection1)
        writeln(element);

    auto collection2 = [1, 2, 3];
    foreach (element; collection1)
        writeln(element);

    auto collection3 = [1:10, 2:20, 3:30];
    foreach (element; collection3)
        writeln(element);

    foreach (key, value; collection3)
        writeln(key, " ", value);
}

{{out}}

A
B
C
A
B
C
10
20
30
1 10
2 20
3 30

Dao

items = { 1, 2, 3 }
for( item in items ) io.writeln( item )

Delphi

for..in loops were added in Delphi 2005.

Supports arrays (single, multidimensional, and dynamic), sets, strings, collections and any class or interface that implements GetEnumerator().

program LoopForEach;

{$APPTYPE CONSOLE}

var
  s: string;
begin
  for s in 'Hello' do
    Writeln(s);
end.

Output:

H
e
l
l
o

Dragon


for (value : array) {
   showln array
}

Dyalect

for i in [1,2,3] {
   print(i)
}

This code would work for any type that has a method "iter" (returning an iterator). In fact a runtime environment silently calls this method for you here and creates an iterator out of an array. The code above is absolutely identical to:

for i in [1,2,3].iter() {
   print(i)
}

This would perfectly work with any custom iterator as well:

func myCollection() {
    yield 1
    yield 2
    yield 3
}

for i in myCollection() {
   print(i)
}

All three code samples would output:

1
2
3

E

for e in theCollection {
    println(e)
}

In E, the for ... in ... loop is also used for iterating over numeric ranges; see [[Loop/For#E]].

EchoLisp


(define my-list '( albert simon antoinette))
(for ((h my-list)) (write h))
    albert simon antoinette

(define my-vector #(55 66 soixante-dix-sept))
(for (( u my-vector)) (write u))
    55 66 soixante-dix-sept

(define my-string "Longtemps")
(for ((une-lettre my-string)) (write une-lettre))
    "L" "o" "n" "g" "t" "e" "m" "p" "s"

;; etc ... for other collections like Streams, Hashes, Graphs, ...

Efene

Any data structure can be printed as a whole, preformated:

io.format("~p~n", [Collection])

However, to iterate over each element of a list, Efene uses lists.map/2, except in the case of IO where lists.foreach/2 has to be used as the evaluation order is defined to be the same as the order of the elements in the list.

lists.foreach(fn (X) { io.format("~p~n", [X]) }, Collection)

Eiffel

{{works with|EiffelStudio|6.6 beta (with provisional loop syntax)}} The iteration (foreach) form of the Eiffel loop construct is introduced by the keyword across.

            across my_list as ic loop print (ic.item) end

The local entity ic is an instance of the library class ITERATION_CURSOR. The cursor's feature item provides access to each structure element. Descendants of class ITERATION_CURSOR can be created to handle specialized iteration algorithms. The types of objects that can be iterated across (my_list in the example) are based on classes that inherit from the library class ITERABLE

Boolean expression variant

The iteration form of the Eiffel loop can also be used as a boolean expression when the keyword loop is replaced by either all (effecting [[wp:Universal quantification|universal quantification]]) or some (effecting [[wp:Existential quantification|existential quantification]]).

This iteration is a boolean expression which is true if all items in my_list have counts greater than three:

            across my_list as ic all ic.item.count > 3 end

Whereas, the following is true if at least one item has a count greater than three:

            across my_list as ic some ic.item.count > 3 end

Ela

open monad io

each [] = do return ()
each (x::xs) = do
  putStrLn $ show x
  each xs

Elena

ELENA 4.1 :

import system'routines;
import extensions;

public program()
{
    var things := new string[]::("Apple", "Banana", "Coconut");

    things.forEach:(thing)
    {
        console.printLine:thing
    }
}

Elixir

iex(1)> list = [1,3.14,"abc",[3],{0,5}]
[1, 3.14, "abc", [3], {0, 5}]
iex(2)> Enum.each(list, fn x -> IO.inspect x end)
1
3.14
"abc"
[3]
{0, 5}
:ok

Emacs Lisp

For a list either dolist macro

(dolist (x '(1 2 3 4))
  (message "x=%d" x))

or mapc function

(mapc (lambda (x)
        (message "x=%d" x))
      '(1 2 3 4))

dolist and mapc are both builtin in current Emacs. For past Emacs both can be had from cl.el with for instance (eval-when-compile (require 'cl)).

cl.el also offers a loop macro similar in style to [[#Common Lisp|Common Lisp]].

Erlang

Any data structure can be printed as a whole, preformated:

io:format("~p~n",[Collection]).

However, to iterate over each element of a list, Erlang uses lists:map/2, except in the case of IO where lists:foreach/2 has to be used as the evaluation order is defined to be the same as the order of the elements in the list.

lists:foreach(fun(X) -> io:format("~p~n",[X]) end, Collection).

ERRE

It's an extension of 'standard' FOR loop: constant list must be explicit.


      FOR INDEX$=("The","quick","brown","fox","jumps","over","the","lazy","dog.") DO
        PRINT(INDEX$;" ";)
      END FOR
      PRINT

Euphoria

{{works with|OpenEuphoria}} include std/console.e

sequence s = {-2,-1,0,1,2} --print elements of a numerical list for i = 1 to length(s) do ? s[i] end for

puts(1,'\n')

s = {"Name","Date","Field1","Field2"} -- print elements of a list of 'strings' for i = 1 to length(s) do printf(1,"%s\n",{s[i]}) end for

puts(1,'\n')

for i = 1 to length(s) do -- print subelements of elements of a list of 'strings' for j = 1 to length(s[i]) do printf(1,"%s\n",s[i][j]) end for puts(1,'\n') end for

if getc(0) then end if


{{out}}

```txt

-2
-1
0
1
2

Name
Date
Field1
Field2

N
a
m
e

D
a
t
e

F
i
e
l
d
1

F
i
e
l
d
2

Factor

{ 1 2 4 } [ . ] each

Fantom

Use each method to iterate over a collection of items in a List.

class Main
{
  public static Void main ()
  {
    Int[] collection := [1, 2, 3, 4, 5]
    collection.each |Int item|
    {
      echo (item)
    }
  }
}

friendly interactive shell

Unlike, bash or csh, the PATH variable is automatically converted to real array.

for path in $PATH
    echo You have $path in PATH.
end

Sample output:


You have /bin in PATH.
You have /usr/bin in PATH.

Fortran

program main

 implicit none

 integer :: i
 character(len=5),dimension(5),parameter :: colors = ['Red  ','Green','Blue ','Black','White']

 !using a do loop:
 do i=1,size(colors)
   write(*,'(A)') colors(i)
 end do

 !this will also print each element:
 write(*,'(A)') colors

end program main

Forth

create a 3 , 2 , 1 ,
: .array ( a len -- )
  cells bounds do  i @ .  cell +loop ;     \ 3 2 1

Frink

Frink's for loop is actually a "for each" loop which can iterate over built-in collection types including arrays, sets, dictionaries, enumerating expressions, and Java types such as Map, Iterator, Enumeration, etc.


array = [1, 2, 3, 5, 7]
for n = array
   println[n]

=={{header|F_Sharp|F#}}== We can use ''for'' directly or list iteration.

for i in [1 .. 10] do printfn "%d" i

List.iter (fun i -> printfn "%d" i) [1 .. 10]

GAP

for p in AlternatingGroup(4) do
    Print(p, "\n");
od;

()
(1,3,2)
(1,2,3)
(1,4,3)
(2,4,3)
(1,3)(2,4)
(1,2,4)
(1,4)(2,3)
(2,3,4)
(1,3,4)
(1,2)(3,4)
(1,4,2)

Go

range works with all of the built-in container-types. With one variable (''i''), it gives you the key/index of every item. With two variables (''i'', ''x''), it gives you both the key/index and value/item. For channels, only the single-variable variant is allowed.

func printAll(values []int) {
   for i, x := range values {
      fmt.Printf("Item %d = %d\n", i, x)
   }
}

Groovy

"for" loop:

def beatles = ["John", "Paul", "George", "Ringo"]

for(name in beatles) {
    println name
}

"each()" method:

Though technically not a loop, most Groovy programmers would use the somewhat more terse "each()" method on the list itself in preference to the "for" loop construct.

beatles.each {
    println it
}

Output (same for either):

John
Paul
George
Ringo

Halon

$things = ["Apple", "Banana", "Coconut"];

foreach ($things as $thing) {
    echo $thing;
}

Haskell

import Control.Monad (forM_)
forM_ collect print

which is the same as

mapM_ print collect

Haxe

var a = [1, 2, 3, 4];

for(i in a)
    Sys.println(i);

HicEst

CHARACTER days="Monday Tuesday Wednesday Thursday Friday Saturday Sunday "

items = INDEX(days, ' ', 256)          ! 256 = count option
DO j = 1, items
  EDIT(Text=days, ITeM=j, Parse=today)
  WRITE() today
ENDDO

Hy

(for [x collection] (print x))

Io

collection foreach(println)

=={{header|Icon}} and {{header|Unicon}}== The example below X can be a list, string, table or other data type.

procedure main()
X := [1,2,3,-5,6,9]
every x := !L do
   write(x)
end

This loop can be written somewhat more concisely as:

every write(!L)

J




## Java

{{works with|Java|1.5+}}

```java>Iterable<Type
 collect;
...
for(Type i:collect){
   System.out.println(i);
}

This works for any array type as well as any type that implements the Iterable interface (including all Collections).

{{works with|Java|1.8+}}


Iterable collect;
...
collect.forEach(o -> System.out.println(o));

This works with any Iterable, but not with arrays.

JavaScript

For arrays in ES5, we can use '''Array.forEach()''':

"alpha beta gamma delta".split(' ').forEach(
  function (x) {
    console.log(x);
  }
);

Output:

alpha
beta
gamma
delta

though it will probably be more natural – dispensing with side-effects, and allowing for easier composition of nested functions – to simply use '''Array.map()''',

console.log("alpha beta gamma delta".split(' ').map(
  function (x) {
    return x.toUpperCase(x);
  }
).join('\n'));

Output:

ALPHA
BETA
GAMMA
DELTA

or, more flexibly, and with greater generality, obtain an accumulating fold from '''Array.reduce()'''

console.log(
  "alpha beta gamma delta".split(' ').reduce(
    function (a, x, i, lst) {
      return lst.length - i + '. ' + x + '\n' + a;
    }, ''
  )
)

Output:

1. delta
2. gamma
3. beta
4. alpha

More generally, the following works for any object, including an array. It iterates over the keys of an object.

for (var a in o) {
    print(o[a]);
}

However, it has the often unwanted feature that it lists inherited properties and methods of objects as well as the ones directly set on the object -- consider whether to filter out such properties inside the loop, for example:

for (var a in o) {
    if (o.hasOwnProperty(a)) {
        print(o[a]);
    }
}

{{works with|JavaScript|1.6}} ;Deprecated There is also a [https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Statements/for_each...in for each in] construct that iterates over the values of an object:

h = {"one":1, "two":2, "three":3}
for (x in h) print(x);
/*
two
one
three
*/

for each (y in h) print(y);
/*
2
1
3
*/

{{works with|ECMAScript|6th edition}} There is also a [https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Statements/for...of for of] construct that iterates over the values of an object:

h = {"one":1, "two":2, "three":3}
for (x in h) print(x);
/*
two
one
three
*/

for (y of h) print(y);
/*
2
1
3
*/

Jsish

Jsi supports ''for of'' for looping over element of an array.

for (str of "alpha beta gamma delta".split(' ')) { puts(str); }

{{out}}

alpha
beta
gamma
delta

Julia

{{trans|Python}}

for i in collection
   println(i)
end

The Julia for statement is always a "foreach", and the built-in start:end or start:step:end "range" syntax can be used for iteration over arithmetic sequences. Many Julia objects support iteration: arrays and tuples iterate over each item, strings iterate over each character, dictionaries iterate over (key,value) pairs, numeric scalars provide a length-1 iteration over their value, and so on.

jq

'''Iterables''':

In this section, the array defined by "example" is used as an example:

def example: [1,2];

jq has two types of iterables -- JSON arrays and JSON objects. In both cases, the ".[]" filter may be used to iterate through the values, it being understand that for objects, the "values" are the values associated with the keys:

example | .[]
# or equivalently: example[]

{"a":1, "b":2} | .[]
# or equivalently: {"a":1, "b":2}[]

In both cases, the output is the stream consisting of the values 1 followed by 2.

Sometimes it is necessary to use an alternative to ".[]". For example, one might want to generate an index along with the array elements. In such cases, the "range(m;n)" generator, which performs a similar role to C's "for(i=m; i<n; i++)", can be used for array. Here is how range/2 would be used to perform the task for an array:

example | . as $a | range(0; length) | $a[.]

For JSON objects, the corresponding technique involves using keys, e.g.


 {"a":1, "b":2} | . as $o | keys | map( [., $o[.]] )

produces: [["a",1],["b",2]]

'''Strings''':

To convert the constituent characters (or technically, codepoints) of a string into a stream of values, there are two techniques illustrated by these examples:

"abc" | . as $s | range(0;length) | $s[.:.+1]

"abc" | explode | map( [.]|implode) | .[]

In both cases, the result is the stream of values: "a", "b", "c".

Kotlin

// version 1.0.6

fun main(args: Array<String>) {
    val greek = arrayOf("alpha", "beta", "gamma", "delta")
    for (letter in greek) print("$letter ")
    println()
    // or alternatively
    greek.forEach { print("$it ") }
    println()
}

{{out}}


alpha beta gamma delta
alpha beta gamma delta

Lasso

array(1,2,3) => foreach { stdoutnl(#1) }

with i in array(1,2,3) do { stdoutnl(#i) }

K

   {`0:$x} ' !10

   _sin ' (1; 2; 3;)

LFE

(lists:foreach
  (lambda (x)
    (io:format "item: ~p~n" (list x)))
  (lists:seq 1 10))

LabVIEW

[[LabVIEW]] has a feature known as an Auto-Indexed Tunnel. It is the very small orange box on the lower left of the for loop.
{{VI solution|LabVIEW_Loops_Foreach.png}}

Lang5

say.(*) . ;
5 iota >>say.

LIL

# Loops/Foreach, in LIL
set collection [list 1 2 "three"]
append collection [list 4 5 six]  # appended as a single item in collection
print "Collection is: $collection"

# using default "i" variable name set for each item
foreach $collection {print $i}

# user named variable in the steps, retrieving accumulated result of loop
# each loop step quotes two copies of the item
set newlist [foreach j $collection {quote $j $j}]
print "Result of second foreach: $newlist"

{{out}}

prompt$ lil loopsForeach.lil
Collection is: 1 2 three {4 5 six}
1
2
three
4 5 six
Result of second foreach: {1 1} {2 2} {three three} {4 5 six 4 5 six}

Lingo

days = ["monday", "tuesday", "wednesday", "thursday", "friday", "saturday", "sunday"]
repeat with day in days
  put day
end repeat

A callback-based forEach() can be implemented like this:

----------------------------------------
-- One of the five native iterative methods defined in ECMAScript 5
-- @param {list} tList
-- @param {symbol} cbFunc
-- @param {object} [cbObj=_movie]
----------------------------------------
on forEach (tList, cbFunc, cbObj)
  if voidP(cbObj) then cbObj = _movie
  cnt = tList.count
  repeat with i = 1 to cnt
    call(cbFunc, cbObj, tList[i], i, tList)
  end repeat
end

days = ["monday", "tuesday", "wednesday", "thursday", "friday", "saturday", "sunday"]
forEach(days, #alert, _player)

Lisaac

"Lisaac loop foreach".split.foreach { word : STRING;
  word.print;
  '\n'.print;
};

LiveCode

Livecode's ''for each'' operates on chunks which may be words, items, lines, tokens. Example is for items.

repeat for each item x in "red, green, blue"
    put x & cr
    --wait 100 millisec  -- req'd if you want to see in the LC Message Box (akin to repl)
end repeat

Lua

Lua has 2 built-in iterators over tables.

pairs() iterates over all entries in a table, but in no particular order:

t={monday=1, tuesday=2, wednesday=3, thursday=4, friday=5, saturday=6, sunday=0, [7]="fooday"}
for key, value in pairs(t) do
  print(value, key)
end

Output:


0	sunday
fooday	7
2	tuesday
3	wednesday
5	friday
4	thursday
6	saturday
1	monday

ipairs() iterates over table entries with positive integer keys, and is used to iterate over lists in order.

l={'monday', 'tuesday', 'wednesday', 'thursday', 'friday', 'saturday', 'sunday', not_a_number='fooday', [0]='today', [-1]='yesterday' }
for key, value in ipairs(l) do
  print(key, value)
end

Output:


1	monday
2	tuesday
3	wednesday
4	thursday
5	friday
6	saturday
7	sunday

Note that ipairs() ignores non-numeric and non-positive integer keys.

M2000 Interpreter

Iterators we have for Arrays, Inventories and Stacks (containers). Each(object Start to End), or Each(object 1 to -1) or Each(Object, 1,-1). We can use -2 for second from end item. We can use step inside while iterator {} using Iterator=Each(object, new_start, end_item). We can read cursor using ^. So Print k^, k2^, k1^ return positions (from 0 for inventories). We can use more than one iterators for an object.


Module Checkit {
      \\ Inventories may have keys or keys/values
      \\ here keys are values too
      Inventory Alfa="Apple", "Banana", "Coconut"
      \\ key 30 has value 25, other keys have value same as key.
      Inventory Beta=100, 30:=25, 20, 5
      Print "Parallel"
      k=Each(Alfa)
      k1=Each(Alfa End to Start)
      k2=Each(Beta)
      \\ Parallel iterators
      \\ when one of them end then while end too.
      \\ so 5 not printed. Print 100, 25, 20
      While k,k2, k1 {
            Print Eval$(k), Eval$(k1), Eval(k2)
      }
      Print "Nested"
      \\ Nested iterators
      k=Each(Alfa)
      While k {
      k1=Each(Alfa End to Start)
            While k1 {
                  Print Eval$(k), Eval$(k1)
            }
      }
}
Checkit

Maple


for p in [2, 3, 5, 7] do
    print(p);
end do;

Mathematica

Foreach over list of strings

s = (StringSplit@Import["ExampleData/USConstitution.txt"])[[1;;7]];
Do[
 Print@i,
 {i, s}
]

Output:

We
the
People
of
the
United
States,

=={{header|MATLAB}} / {{header|Octave}}==

    list1 = [1,5,6,7,-7,-9];
    for k = list1,    % list1 must be a row vector (i.e. array of size 1xn)
        printf('%i\n',k)
    end;

    list2 = {'AA','BB','CC'};
    for k = list2,    % list2 must be a row vector (i.e. array of size 1xn)
        printf('%s\n',k{1})
    end;

A vectorized version of the code is

  printf('%d\n',list1);
  printf('%s\n',list2{:});

Maxima

for n in [2, 3, 5, 7] do print(n);

MAXScript


arr = for i in 1 to 50 collect ("Number: " + (random 10 99) as string)
makeuniquearray arr
sort arr

for i in arr do print i as string

Metafont

If we have a list of arbitrary items, we can simply use for:

for x = "mary", "had", "a", "little", "lamb": message x; endfor
end

The list can be generated in place by any suitable macro or another loop... e.g. let us suppose we have things like a[n] defined (with maximum n being 10). Then

for x = for i = 1 upto 9: a[i], endfor, a[10]: show x; endfor
end

works more like a foreach; we could make a macro to hide the strangeness of such a code.

min

{{works with|min|0.19.3}}

(1 2 3) 'puts foreach

MiniScript

for i in collection
   print i
end

The MiniScript for statement is always a "foreach", and the standard range intrinsic can be used for iteration over arithmetic sequences. All MiniScript collection types support iteration: lists iterate over each item, strings iterate over each character, and maps/objects iterate over (key,value) pairs.

MOO

things = {"Apple", "Banana", "Coconut"};

for thing in (things)
    player:tell(thing);
endfor

Nemerle

This works on anything which implements the IEnumerable interface.

def things = ["Apple", "Banana", "Coconut"];

foreach (thing in things) WriteLine(thing.ToLower());
foreach (i in [5, 10 .. 100]) Write($"$i\t");

NetRexx

/* NetRexx */
options replace format comments java crossref savelog symbols nobinary

  say
  say 'Loops/Foreach'

  days = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday']
  daysl = Arrays.asList(days)
  daysi = daysl.iterator

  loop while daysi.hasNext
    say daysi.next
    end

NewLISP

(map println '(Apple Banana Coconut))

Nim

var list: seq[string] = @[]
list.add("lorem")
list.add("ipsum")
list.add("dolor")
for i in items(list):
  echo(i)

Output:


lorem
ipsum
dolor

=={{header|Objective-C}}== {{works with|Objective-C|2.0+}} {{works with|GNUstep}} {{works with|Cocoa}}

NSArray *collect;
//...
for(Type i in collect){
   NSLog(@"%@", i);
}

''collect'' can be any object that adopts the NSFastEnumeration protocol.

Or (always using OpenStep compatible frameworks): {{works with|Objective-C|<2.0}}

NSArray *collect;
//...
NSEnumerator *enm = [collect objectEnumerator];
id i;
while( (i = [enm nextObject]) ) {
  // do something with object i
}

Objeck

fruits := ["Apple", "Banana", "Coconut"];
each(i : fruits) {
  fruits[i]->PrintLine();
};

OCaml

List of integers:

List.iter
  (fun i -> Printf.printf "%d\n" i)
  collect_list

Array of integers:

Array.iter
  (fun i -> Printf.printf "%d\n" i)
  collect_array

Oforth

: printMonths | m | Date.Months forEach: m [ m . ] ;

But, apply can be used instead of a loop :




## Octave


```octave
a = [ 1,4,3,2 ];
b = [ 1,2,3,4; 5,6,7,8 ];
for v = a
  disp(v); % output single values: 1,4,3,2
endfor
for v = b
  disp(v); % v is the column vector [1;5], then [2;6] ...
endfor

We can also iterate over structures:

x.a = [ 10, 11, 12 ];
x.b = { "Cell", "ul", "ar" };
for [ val, key ] = x
  disp(key);
  disp(val);
endfor

ooRexx

The OVER loop control keyword is used to select each item in a collection in turn. Open Object Rexx allows the DO block structure keyword to be used to start a loop for backward compatibility with classic Rexx; the LOOP keyword is preferred here as it is self-documenting.

/* Rexx */
say
say 'Loops/Foreach'
out = ''

days = .array~of('Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday')

loop daysi over days
  out ||= daysi' '
  end daysi
say out~strip()

exit

'''Output:'''


Loops/Foreach
Sunday Monday Tuesday Wednesday Thursday Friday Saturday

Oz

declare
  MyList = [1 2 3 4]
in
  {ForAll MyList Show}

  %% or:
  for E in MyList do {Show E} end

PARI/GP

for(i=1,#v,print(v[i]))

or (PARI/GP >= 2.4)

apply(x->print(x),v)

Pascal

See [[Loops/Foreach#Delphi | Delphi]]

Perl

foreach my $i (@collection) {
   print "$i\n";
}

The keyword for can be used instead of foreach. If a loop variable (here $i) is not given, then $_ is used.

A more compact notation using perl statement modifier:

print "$_\n"  foreach @collection

In perl, it is possible to loop against an explicit list, so there is no need to define a container:

foreach $l ( "apples", "bananas", "cherries" ) {
  print "I like $l\n";
}

Perl 6

{{works with|Rakudo|2015.10-40}}

say $_ for @collection;

Perl 6 leaves off the each from foreach, leaving us with for instead. The variable $_ refers to the current element, unless you assign a name to it using ->.

for @collection -> $currentElement { say $currentElement; }

Perl 6 will do it's best to put the topic at the right spot.

.say for @collection;
for @collection { .say };

Iteration can also be done with hyperoperators. In this case it's a candidate for autothreading and as such, execution order may vary. The resulting list will be in order.

.say;
@collection>>.=&infix:<+>(2); # increment each element by 2

Phix

sequence s = {-2,"field",3.14159268979,{"this","that"}}
for i=1 to length(s) do
    ?s[i]
end for

PHL

var numbers = 1..10;

numbers each # (number) [
    printf("%i\n", number);
];

PHP

foreach ($collect as $i) {
   echo "$i\n";
}

foreach ($collect as $key => $i) {
   echo "\$collect[$key] = $i\n";
}

foreach can also iterate over objects. By default it iterates over all visible fields of an object.

PicoLisp

(mapc println '(Apple Banana Coconut))

Pike

int main(){
   array(int|string) collect = ({109, "Hi", "asdf", "qwerty"});
   foreach(collect, int|string elem){
      write(elem + "\n");
   }
}

Iterating over the keys and values of a mapping (dictionary):

int main(){
    mapping(string:string) coll = (["foo":"asdf", "bar":"qwer", "quux":"zxcv"]);
    foreach (coll;string key;string val)
        write(key+" --> "+val+"\n");
    }
}

PL/I

declare A(10) fixed binary;
do i = lbound(A,1) to hbound(A,1);
   put skip list (A(i));
end;

Pop11

Iteration over list:

lvars el, lst = [1 2 3 4 foo bar];
for el in lst do
   printf(el,'%p\n');
endfor;

PostScript

The forall operator performs a loop over a collection (array, string or dictionary). Strings and arrays can be treated very much the same:

[1 5 3 2] { = } forall
(abc) { = } forall

but dictionaries take a little more work since a key/value pair is pushed on the stack in each iteration:

 {
  exch (Key: ) print
  =
  (Value: ) print
  =
} forall

PowerShell


$colors = "Black","Blue","Cyan","Gray","Green","Magenta","Red","White","Yellow",
          "DarkBlue","DarkCyan","DarkGray","DarkGreen","DarkMagenta","DarkRed","DarkYellow"

foreach ($color in $colors)
{
    Write-Host "$color" -ForegroundColor $color
}

{{Out}}


Black
Blue
Cyan
Gray
Green
Magenta
Red
White
Yellow
DarkBlue
DarkCyan
DarkGray
DarkGreen
DarkMagenta
DarkRed
DarkYellow

Prolog

For example :

?- foreach(member(X, [red,green,blue,black,white]), writeln(X)).
red
green
blue
black
white
true.

Python

for i in collection:
   print i

Note: The Python for statement is always a ''"foreach" ...'' and the range() and xrange() built-in functions are used to generate lists of indexes over which it will iterate as necessary. The majority of Python objects support iteration. Lists and tuples iterate over each item, strings iterate over each character, dictionaries iterate over keys, files iterate over lines, and so on.

For example:

lines = words = characters = 0
f = open('somefile','r')
for eachline in f:
    lines += 1
    for eachword in eachline.split():
        words += 1
        for eachchar in eachword:
            characters += 1

print lines, words, characters

Whether for loops over the elements of the collection in order depends on the collection having an inherent order or not. Elements of strings (i.e. characters), tuples and lists, for example, are ordered but the order of elements in dictionaries and sets is not defined.

One can loop over the key/value pairs of a dictionary in ''alphabetic'' or ''numeric'' key order by sorting the sequence of keys, provided that the keys are all of ''comparable'' types. In Python 3.x a sequence of mixed numeric and string elements is not sortable (at least not with the default invocation of sorted()), whereas in Python 2.x numeric types are sorted according to their string representation by default:

d = {3: "Earth", 1: "Mercury", 4: "Mars", 2: "Venus"}
for k in sorted(d):
    print("%i: %s" % (k, d[k]))

d = {"London": "United Kingdom", "Berlin": "Germany", "Rome": "Italy", "Paris": "France"}
for k in sorted(d):
    print("%s: %s" % (k, d[k]))

{{works with|Python|2.x}}

d = {"fortytwo": 42, 3.14159: "pi", 23: "twentythree", "zero": 0, 13: "thirteen"}
for k in sorted(d):
    print("%s: %s" % (k, d[k]))

R

a <- list("First", "Second", "Third", 5, 6)
for(i in a) print(i)

Racket


#lang racket

;; an example sequence
(define sequence '("something" 1 2 "foo"))

;; works for any sequence
(for ([i sequence])
  (displayln i))

REBOL

REBOL [
	Title: "Loop/Foreach"
	URL: http://rosettacode.org/wiki/Loop/Foreach
]

x: [Sork Gun Blues Neds Thirst Fright Catur]

foreach i x [prin rejoin [i "day "]]  print ""

; REBOL also has the 'forall' construct, which provides the rest of
; the list from the current position.

forall x [prin rejoin [x/1 "day "]]  print ""

Output:

Sorkday Gunday Bluesday Nedsday Thirstday Frightday Caturday
Sorkday Gunday Bluesday Nedsday Thirstday Frightday Caturday

Red

 blk: ["John" 23 "dave" 30 "bob" 20 "Jeff" 40]
>> foreach item blk [print item]
John
23
dave
30
bob
20
Jeff
40
>>  foreach [name age] blk [print [name "is" age "years old"]]
John is 23 years old
dave is 30 years old
bob is 20 years old
Jeff is 40 years old

>> forall blk [print blk]
John 23 dave 30 bob 20 Jeff 40
23 dave 30 bob 20 Jeff 40
dave 30 bob 20 Jeff 40
30 bob 20 Jeff 40
bob 20 Jeff 40
20 Jeff 40
Jeff 40
40

Retro

Retro has '''for-each''' combinators for operating on elements of various data structures.

# Strings

This will display the ASCII code for each character in a string

~~~
'This_is_a_message [ n:put sp ] s:for-each
~~~

# Array

Display each element

~~~
{ #1 #2 #3 }  [ n:put sp ] a:for-each
~~~

# Linked List

Using the dictionary as an example, display each name

~~~
&Dictionary [ d:name s:put sp ] d:for-each
~~~

REXX

days = 'zuntik montik dinstik mitvokh donershtik fraytik shabes'

  do j=1  for words(days)              /*loop through days of the week. */
  say word(days,j)                     /*display the weekday to screen. */
  end   /*j*/
                                       /*stick a fork in it, we're done.*/

Ring


aList = "Welcome to the Ring Programming Language"
for n in aList
    see n + nl
next

Ruby

for i in collection do
  puts i
end

This is syntactic sugar for:

collection.each do |i|
  puts i
end

There are various flavours of each that may be class-dependent: [http://www.ruby-doc.org/core/classes/String.html#M000862 String#each_char], [http://www.ruby-doc.org/core/classes/Array.html#M002174 Array#each_index], [http://www.ruby-doc.org/core/classes/Hash.html#M002863 Hash#each_key], etc

Rust

Rust's for-loop already is a foreach-loop.

let collection = vec![1,2,3,4,5];
for elem in collection {
    println!("{}", elem);
}

Do note that Rust moves values by default and doesn't copy them. A vector would be unusable after looping over it like above. To preserve it, borrow it or use an Iter, to mutate values do a mutable borrow or create an IterMut. To get an immutable reference omit the mut-part.

let mut collection = vec![1,2,3,4,5];
for mut_ref in &mut collection {
// alternatively:
// for mut_ref in collection.iter_mut() {
    *mut_ref *= 2;
    println!("{}", *mut_ref);
}

// immutable borrow
for immut_ref in &collection {
// alternatively:
// for immut_ref in collection.iter() {
    println!("{}", *immut_ref);
}

Since Rust 1.21 foreach can be used explicitly executing a closure on each element.

let collection = vec![1, 2, 3, 4, 5];
collection.iter().for_each(|elem| println!("{}", elem));

Salmon

iterate (x; ["Red", "Green", "Blue"])
    x!;

output:


Red
Green
Blue

SAS

/* Initialize an array with integers 1 to 10, and print their sum */
data _null_;
array a a1-a10;
n=1;
do over a;
  a=n;
  n=n+1;
end;
s=sum(of a{*});
put s;
run;

Sather

class MAIN is
  main is
     num:ARRAY{INT} := |1, 5, 4, 3, 10|;
     loop
       -- the iterator elt! behaves like a "foreach",
       -- yielding the next element of the array at each iteration
       #OUT + num.elt! + "\n";
     end;
  end;
end;

Scala

val collection = Array(1, 2, 3, 4)
collection.foreach(println)

Alternatively:

(element <- 1 to 4).foreach(println)

Scheme

List:

(for-each
  (lambda (i) (display i) (newline))
  the_list)

Scilab

{{works with|Scilab|5.5.1}} for e=["a","b","c"] printf("%s\n",e) end


{{out}}

```txt
a
b
c

Seed7

The for loop of Seed7 can be used to loop over the elements of a container.

$ include "seed7_05.s7i";

var array string: things is [] ("Apple", "Banana", "Coconut");

const proc: main is func
  local
    var string: thing is "";
  begin
    for thing range things do
      writeln(thing);
    end for;
  end func;

Self

aCollection do: [| :element | element printLine ].

(Provided that the objects in the collection understand the printLine method).

SETL

S := {1,2,3,5,8,13,21,34,55,89};
for e in S loop
    print(e);
end loop;

Sidef

'''foreach''' loop:

foreach [1,2,3] { |i|
    say i
}

'''for-in''' loop:

for i in [1,2,3] {
    say i
}

'''.each''' method:

[1,2,3].each { |i|
    say i
}

Slate

c do: [| :obj | print: obj].

Smalltalk

aCollection do: [ :element | element displayNl ].

(Provided that the objects in the collection understand the displayNl method).

Snabel

Prints foo, bar & baz followed by newlines.

['foo' 'bar' 'baz'] &say for

Sparkling

Sparkling currently has no "foreach" construct, but there's a "foreach" function in the standard library:

let hash = { "foo": 42, "bar": 1337, "baz": "qux" };
foreach(hash, function(key, val) {
    print(key, " -> ", val);
});

Standard ML

List of integers:

app
  (fn i => print (Int.toString i ^ "\n"))
  collect_list

Array of integers:

Array.app
  (fn i => print (Int.toString i ^ "\n"))
  collect_array

Stata

local a 2 9 4 7 5 3 6 1 8
foreach i in `a' {
	display "`i'"
}

Suneido

for i in #(1, 2, 3)
    Print(i)

Swift

for i in [1,2,3] {
   print(i)
}

This works for any type that conforms to the SequenceType protocol (including arrays, collections, generators, ranges).

Alternately: {{works with|Swift|2.x+}}

[1,2,3].forEach {
   print($0)
}

SystemVerilog

program main;
  int values[$];

  initial begin
    values = '{ 1, 3, 7, 11 };
    foreach (values[i]) begin
       $display( "%0d --> %0d", i, values[i] );
    end
  end
endprogram

Tcl

foreach i {foo bar baz} {
    puts "$i"
}

Note that foreach also accepts multiple variables:

foreach {x y} {1 2 3 4} {
    puts "$x,$y"
}

And also multiple lists:

foreach i {1 2 3} j {a b c} {
    puts "$i,$j"
}

Or any combination of variables/list:

foreach i {1 2 3} {x y} {a b c d e f} {
    puts "$i,$x,$y"
}

Trith

[1 2 3 4 5] [print] each

TUSCRIPT

$$ MODE TUSCRIPT
week="Monday'Tuesday'Wednesday'Thursday'Friday'Saterday'Sunday"
LOOP day=week
PRINT day
ENDLOOP

Output:


Monday
Tuesday
Wednesday
Thursday
Friday
Saterday
Sunday

UNIX Shell

To iterate any single list, you use a for loop. {{works with|Bourne Shell}}

for file in *.sh; do
  echo "filename is $file"
done

If the list is in a shell parameter (like PATH), you adjust IFS. {{works with|Bourne Shell}}

PATH=/usr/bin:/bin:/usr/sbin:/sbin:/usr/X11R6/bin:/usr/local/bin

oldifs=$IFS
IFS=:
for dir in $PATH; do
  echo search $dir
done
IFS=$oldifs

Some shells have real arrays. The for loop can also iterate these. {{works with|Bash}}

collection=("first" "second" "third" "fourth" "something else")
for x in "${collection[@]}"; do
  echo "$x"
done

{{works with|pdksh|5.2.14}}

set -A collection "first" "second" "third" "fourth" "something else"
for x in "${collection[@]}"; do
  echo "$x"
done

=

C Shell

=

set collection=(first second third fourth "something else")
foreach x ($collection:q)
	echo $x:q
end

V

[1 2 3] [puts] step

Vim Script

Vim Script's for-loop is actually a foreach-loop and iterates through a list.

for i in ["alpha", "beta", 42, 5.54]
    echo i
endfor

Wart

each x '(1 2 3)
  prn x

WDTE

 import 'arrays';
let s => import 'stream';

a.stream [5; 7; 3]
-> s.map (io.writeln io.stdout)
-> s.drain
;

XLISP

XLISP's FOR-EACH applies a procedure to each member of a list in turn.

(FOR-EACH PRINT '(CYRUS CAMBYSES DARIUS XERXES ARTAXERXES))

{{out}}

CYRUS
CAMBYSES
DARIUS
XERXES
ARTAXERXES

XPL0

Translation of C example:

include c:\cxpl\codes;
int List, I;
[List:= ["Red", "Green", "Blue", "Black", "White"];
for I:= 0, 5-1 do
        [Text(0, List(I));  CrLf(0)];
]

XSLT

For-each is the only iteration construct that is built into XSLT. All other iteration is either implied by applying a template to all members matching an XPath expression, or built from recursive application of a template. You have access to something like a loop counter with the one-based "position()" function.

<fo:block font-weight="bold">Adults:</fo:block>
<xsl:for-each select="person[@age &gt;= 21]">
  <fo:block><xsl:value-of select="position()"/>. <xsl:value-of select="@name"/></fo:block>
</xsl:for-each>

zig

const warn = @import("std").debug.warn;

pub fn main() void {
    const items = []i16{ 0, 1, 1, 2, 3, 5, 8 };

    for (items) |i| {
        warn("{}\n", i);
    }
}

zkl

{{trans|XPL0}}

foreach c in (T("Red","Green","Blue","Black","White"))
  { print(c," "); }

{{out}}

Red Green Blue Black White

Other forms of foreach, one that breaks apart a container into elements and one line nested loops.

foreach x,y,z in (T(T(1,2,3), T(4,5,6))) { println(x,y,z) }
foreach x,y,z in (T(1,2,3), T(4,5), T(6)){ println(x,y,z) }

{{out}}


123
456



146
156
246
256
346
356

{{omit from|GUISS}}