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Loops/Foreach

(Redirected from Foreach)
Loops/Foreach
You are encouraged to solve this task according to the task description, using any language you may know.

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.

11l

Translation of: C#
`V things = [‘Apple’, ‘Banana’, ‘Coconut’] L(thing) things   print(thing)`

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
```

Action!

In Action! there is no for-each loop.

`PROC Main()  DEFINE PTR="CARD"  BYTE i  PTR ARRAY items(10)  items(0)="First"   items(1)="Second"  items(2)="Third"   items(3)="Fourth"  items(4)="Fifth"   items(5)="Sixth"  items(6)="Seventh" items(7)="Eighth"  items(8)="Ninth"   items(9)="Tenth"   PrintE("In Action! there is no for-each loop")  PutE()  FOR i=0 TO 9  DO    PrintE(items(i))  ODRETURN`
Output:
```In Action! there is no for-each loop

First
Second
Third
Fourth
Fifth
Sixth
Seventh
Eighth
Ninth
Tenth
```

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;`

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

`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

`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 literalforeach 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 = 20var b = 10foreach 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 numbersfunction squares (start, end) {    for (var i = start ; i < end ; i++) {        yield i*i    }} var start = 10var 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 integersinteger i, v; for (i, v in list(2, 3, 5, 7, 11, 13, 17, 18)) {}`

ALGOL 68

Works with: ALGOL 68 version Standard - no extensions to language used
Works with: ALGOL 68G version Any - tested with release mk15-0.8b.fc9.i386
Works with: ELLA ALGOL 68 version 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.
```

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

ALGOL 68RS and algol68toc have a FORALL loop, the following is equivalent to the example above:

`FORALL index IN collection DO  print((collection[index]," "))OD`

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 fruitend repeat`

Arturo

`arr: ["one" "two" "three"] dict: #[	    name:		"John"	surname:	"Doe"	age:		34] loop arr 'item ->    print item loop dict [key val]->    print [key "=>" val]`
Output:
```one
two
three
name => John
surname => Doe
age => 34```

AutoHotkey

`string = mary,had,a,little,lambLoop, 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 workBEGIN {  for (el in "apples","bananas","cherries") {    print "I like " el  }}`

BASIC

BaCon

BaCon includes support for delimited strings. Delimited strings form a type of collection. Along with this support is a `for in` loop. Not quite a `for each` but pretty close.

`OPTION COLLAPSE TRUEFOR x\$ IN "Hello cruel world"    PRINT x\$NEXT FOR y\$ IN "1,2,\"3,4\",5" STEP ","    PRINT y\$NEXT`
Output:
```prompt\$ bacon -q forin.bac >/dev/null
prompt\$ ./forin
Hello
cruel
world
1
2
"3,4"
5```

The `OPTION COLLAPSE TRUE` statements prevents empty results when multiple delimiters appear together. The default delimiter is space, and can be changed with `OPTION DELIM x` where x is a static string literal.

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 iPRINT`

Output:

`The quick brown fox jumps over the lazy dog.`

BBC BASIC

`      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 ARRAY20 REM *** FILL ARRAY WITH WORDS ***30 FOR I = 0 TO 840 READ A\$(I)50 NEXT60 REM *** PRINT ARRAY CONTENTS ***70 FOR I = 0 TO 880 PRINT A\$(I)" ";90 NEXT100 END1000 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 PrintSleep`
Output:
``` 1  2  3  4  5  6  7  8  9  10  11
```

Gambas

`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`
Output:
```0 1 2 3 4 5 6 7 8 9
```

IS-BASIC

`100 STRING COLLECTION\$(1 TO 9)*8110 LET I=1120 DO 130   READ IF MISSING EXIT DO:COLLECTION\$(I)140   LET I=I+1150 LOOP 160 FOR J=1 TO I-1170   PRINT COLLECTION\$(J);" ";180 NEXT 190 DATA The,quick,brown,fox,jumps,over,the,lazy,dog.`

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 onlyprogram. 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 `

Lambdatalk

` {def collection alpha beta gamma delta} -> collection {S.map {lambda {:i} {br}:i} {collection}} ->alpha beta gamma delta or {def S.foreach {lambda {:s}  {if {S.empty? {S.rest :s}}   then {S.first :s}   else {S.first :s} {br}{S.foreach {S.rest :s}}}}} {S.foreach {collection}}->alpha beta gamma delta  `

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 +1loop until 1 =2 end`
```Not good!
Hardly good!
Just good!
Quite good!
Really good!
Very good!
Fantastically good!
```

NS-HUBASIC

`10 DIM A\$(9) : REM DECLARE STRING ARRAY20 REM ADD DATA TO ARRAY AND PRINT ARRAY CONTENTS30 FOR I=0 TO 840 READ A\$(I)50 PRINT A\$(I)" ";60 NEXT70 DATA THE, QUICK, BROWN, FOX, JUMPS, OVER, THE, LAZY, DOG.`

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`

TI-89 BASIC

`Local i,strsDefine 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 FruitEnd Sub`

VBScript

`items = Array("Apple", "Orange", "Banana") For Each x In items    WScript.Echo xNext`

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`

Yabasic

`//Yabasic tampoco tiene una construcción ForEach. //Mediante un bucle FOR iteramos a través de una matriz por índice. //READ-DATA se usa para rellenar la matriz dim arreglo(10)data 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11for each = 0 to arraysize(a(),1)    read arreglo(each)next each for each = 0 to arraysize(a(),1)    print arreglo(each), " ";next eachprintend`

Batch File

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

Direct usage:

`@echo offfor %%A in (This is a sample collection) do (     echo %%A)`

Using a Collection Variable:

`@echo offset "collection=This is a sample collection"for %%A in (%collection%) do (     echo %%A)`
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] = .123a[1] = 234a[3] = 95.6for (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 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#

`string[] things = {"Apple", "Banana", "Coconut"}; foreach (string thing in things){    Console.WriteLine(thing);}`

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;}`

Chapel

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

Clojure

`(doseq [item collection] (println item))`

CLU

As in Python (which no doubt got the idea from CLU), every for loop in CLU is really a foreach, and iterating over a range of numbers is done by using an iterator (e.g. `int\$from_to`).

Unlike Python, the for loop only accepts iterators, and collections are not automatically cast into iterators. To loop over the elements of an array, one needs to explicitly use the `elements` iterator.

`start_up = proc ()    po: stream := stream\$primary_output()     words: array[string] := array[string]\$        ["enemy", "lasagna", "robust", "below", "wax"]     for word: string in array[string]\$elements(words) do        stream\$putl(po, word)    endend start_up`

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:

Translation of: 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 thingend-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)`

or

`(dolist (x the-list) (print x))`

or

`(use-package :iterate)(iter  (for x in the-list)  (print x))`

Using DO

` (let ((the-list '(1 7 "foo" 1 4)))	; Set the-list as the list  (do ((i the-list (rest i)))		; Initialize to the-list and set to rest on every loop      ((null i))			; Break condition    (print (first i))))	                ; On every loop print list's first element `
Output:
```1
7
"foo"
1
4
```

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);        }`
Output:
```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 value} `

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 version 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 universal quantification) or `some` (effecting 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 5.0 :

`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)13.14"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.

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 listfor 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 `
Output:
```-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
```

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]`

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)    }  }}`

Fennel

sequential table

`(each [k v (ipairs [:apple :banana :orange])]  (print k v))`
Output:
```1       apple
2       banana
3       orange```

key-value table

`(each [k v (pairs {:apple :x :banana 4 :orange 3})]  (print k v))`
Output:
```apple   x
banana  4
orange  3```

Forth

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

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`

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.
```

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] `

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;}`

`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 optionDO j = 1, items  EDIT(Text=days, ITeM=j, Parse=today)  WRITE() todayENDDO`

Hy

`(for [x collection] (print x))`

Icon and 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)`

Io

`collection foreach(println)`

J

`smoutput each i.10`

Java

Works with: Java version 1.5+
`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 version 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);});`

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"));`

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;}, ""));`

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 version 1.6
Deprecated

There is also a 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);for each (y in h) print(y);`
Works with: ECMAScript version 6th edition

There is also a for of construct that iterates over the values of an object:

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

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".

Jsish

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

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

Julia

Translation of: 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.

K

`   {`0:\$x} ' !10`
`   _sin ' (1; 2; 3;)`

Klingphix

`include ..\Utilitys.tlhy ( -2 "field" 3.14159 ( "this" "that" ) ) len [get ?] for " " input`
Output:
```-2
field
3.14159
("this", "that")```

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()}`
Output:
```alpha beta gamma delta
alpha beta gamma delta
```

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.
This image is a VI Snippet, an executable image of LabVIEW code. The LabVIEW version is shown on the top-right hand corner. You can download it, then drag-and-drop it onto the LabVIEW block diagram from a file browser, and it will appear as runnable, editable code.

Lambdatalk

` {def collection alpha beta gamma delta} -> collection {S.map {lambda {:i} {br}:i} {collection}} ->alpha beta gamma delta or {def S.foreach {lambda {:s}  {if {S.empty? {S.rest :s}}   then {S.first :s}   else {S.first :s} {br}{S.foreach {S.rest :s}}}}} {S.foreach {collection}}->alpha beta gamma delta  `

Lang5

`: >>say.(*) . ;5 iota >>say.`

langur

A for in loop iterates over values and a for of loop iterates over indices.

`for .i in [1, 2, 3] {    writeln .i} val .abc = "abc" for .i in .abc {    writeln .i} for .i of .abc {    writeln .abc[.i]} for .i in .abc {    writeln cp2s .i}`
Output:
```1
2
3
97
98
99
97
98
99
a
b
c```

Lasso

`array(1,2,3) => foreach { stdoutnl(#1) }`
`with i in array(1,2,3) do { stdoutnl(#i) }`

LFE

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

LIL

`# Loops/Foreach, in LILset collection [list 1 2 "three"]append collection [list 4 5 six]  # appended as a single item in collectionprint "Collection is: \$collection" # using default "i" variable name set for each itemforeach \$collection {print \$i} # user named variable in the steps, retrieving accumulated result of loop# each loop step quotes two copies of the itemset newlist [foreach j \$collection {quote \$j \$j}]print "Result of second foreach: \$newlist"`
Output:
```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 dayend 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 repeatend`
`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`

Logo

`foreach [red green blue] [print ?]`

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/Wolfram Language

Foreach over list of strings

`s = ([email protected]["ExampleData/USConstitution.txt"])[[1;;7]]; Do[ [email protected], {i, s}]`

Output:

```We
the
People
of
the
United
States,```

MATLAB / 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 arrsort 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; endforend`

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; endforend`

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

min

Works with: min version 0.19.3
`(1 2 3) 'puts foreach`

MiniScript

`for i in collection   print iend`

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`

Nanoquery

Like Python, Nanoquery supports for...in syntax for list types and strings.

`for item in collection    println itemend`

Some examples:

`for n in {1,3,5,7,9}	print n + " "endprintln for char in "test string"	print charendprintln`
Output:
```1 3 5 7 9
test string```

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

`let list = ["lorem", "ipsum", "dolor"}for item in list:  echo item`
Output:
```lorem
ipsum
dolor```

Objeck

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

Objective-C

Works with: Objective-C version 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 version <2.0
`NSArray *collect;//...NSEnumerator *enm = [collect objectEnumerator];id i;while( (i = [enm nextObject]) ) {  // do something with object i}`

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`

Octave

`a = [ 1,4,3,2 ];b = [ 1,2,3,4; 5,6,7,8 ];for v = a  disp(v); % output single values: 1,4,3,2endforfor 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`

Oforth

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

But, apply can be used instead of a loop :

`#. Date.Months apply`

Ol

` (for-each print '(1 3 4 2))(print)(for-each (lambda (a b c) (print a "-" b "/" c))   '(1 2 3 4)   '(5 6 7 8)   '(a b x z)) `
Output:
```1
3
4
2

1-5/a
2-6/b
3-7/x
4-8/z
```

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 */saysay 'Loops/Foreach'out = '' days = .array~of('Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday') loop daysi over days  out ||= daysi' '  end daysisay 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)`

See 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";}`

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;`

Plain English

`To run:Start up.Create a list.Write each entry in the list to the console.Destroy the list.Wait for the escape key.Shut down. An entry is a thing with a number. A list is some entries. To add a number to a list:Allocate memory for an entry.Put the number into the entry's number.Append the entry to the list. To create a list:Add 1 to the list.Add 2 to the list.Add 3 to the list.Add 6 to the list.Add 7 to the list.Add 9 to the list. To write an entry to the console:Convert the entry's number to a string.Write the string to the console. To write each entry in a list to the console:Get an entry from the list.Loop.If the entry is nil, exit.Write the entry to the console.Put the entry's next into the entry.Repeat.`
Output:
```1
2
3
6
7
9
```

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:

`<</a 25 /b 42>> {  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} `
Output:
```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)).redgreenblueblackwhitetrue. `

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 = 0f = 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 version 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]))`

Quackery

`\$ "Sweet Boom Pungent Prickle Orange" nest\$witheach [ i times sp echo\$ cr ]`
Output:
```    Sweet
Boom
Pungent
Prickle
Orange
```

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)) `

Raku

(formerly Perl 6)

Works with: Rakudo version 2015.10-40
`say \$_ for @collection;`

Raku 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; }`

Raku 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.

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

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]John23dave30bob20Jeff40>>  foreach [name age] blk [print [name "is" age "years old"]]John is 23 years olddave is 30 years oldbob is 20 years oldJeff is 40 years old >> forall blk [print blk]John 23 dave 30 bob 20 Jeff 4023 dave 30 bob 20 Jeff 40dave 30 bob 20 Jeff 4030 bob 20 Jeff 40bob 20 Jeff 4020 Jeff 40Jeff 4040`

ReScript

`let fruits = ["apple", "banana", "coconut"] Js.Array2.forEach(fruits, f => Js.log(f))`

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 + nlnext `

Ruby

`for i in collection do  puts iend`

This is syntactic sugar for:

`collection.each do |i|  puts iend`

There are various flavours of `each` that may be class-dependent: String#each_char, Array#each_index, 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 borrowfor 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 version 5.5.1
`for e=["a","b","c"]    printf("%s\n",e)end`
Output:
```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 (which can be added, if missing).

Most modern Smalltalks allow for a selector symbol to be sent a value: message; which allows for the very compact:

`aCollection do:#displayNl.`

(and because Aikido mentions it: of course this works for any kind of collection (and even things which simply implement a do: method to iterate on something)

`(1 to:6 by:2) do:#displayNl.'hello' do:#displayNl.(Integer primesUpTo:100) do:#displayNl.'/' asFilename directoryContents do:#displayNl.((Smalltalk allClasses collect:#name) asSortedCollection to:2) do:#displayNl. funnyClassLessObject := Plug new                           respondTo:#do:                           with:[:arg |                              arg value:'look ma'.                              arg value:'no classes needed'].funnyClassLessObject do:#displayNl.etc.`
Output:

1 3 5 h e l l o 2 3 5 ... 97 home usr ... tmp cores AAAARecord AATree look ma no classes needed

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 8foreach 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 version 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  endendprogram`

Tailspin

Stream them

` ['a', 'b', 'c'] ... -> !OUT::write `
Output:
`abc`

Lists/arrays can be put through an array transform to get the index as well

` ['a', 'b', 'c'] -> \[i]('\$i;:\$;' -> !OUT::write \) -> !VOID `
Output:
```1:a
2:b
3:c
```

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 TUSCRIPTweek="Monday'Tuesday'Wednesday'Thursday'Friday'Saterday'Sunday"LOOP day=weekPRINT dayENDLOOP`

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=\$IFSIFS=:for dir in \$PATH; do  echo search \$dirdoneIFS=\$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 version 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:qend`

V

`[1 2 3] [puts] step`

Vala

`List<string> things = new List<string> ();things.append("Apple");things.append("Banana");things.append("Coconut"); foreach (string thing in things){  stdout.printf("%s\n", thing);}`

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 iendfor`

Wart

`each x '(1 2 3)  prn x`

WDTE

`let a => import 'arrays';let s => import 'stream'; a.stream [5; 7; 3]-> s.map (io.writeln io.stdout)-> s.drain;`

Wren

`for (f in ["apples", "oranges", "pears"]) System.print(f)`
Output:
```apples
oranges
pears
```

XLISP

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

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

Translation of: XPL0
`foreach c in (T("Red","Green","Blue","Black","White"))  { print(c," "); }`
Output:
`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) }`
Output:
```123
456
```
```146
156
246
256
346
356
```