Loop over multiple arrays simultaneously: Difference between revisions

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=={{header|ALGOL W}}==
<lang algolw>begin
% declare the three arrays %
string(1) array a, b ( 1 :: 3 );
integer array c ( 1 :: 3 );
% initialise the arrays - have to do this element by element in Algol W %
a(1) := "A"; a(2) := "B"; a(3) := "C";
b(1) := "a"; b(2) := "b"; b(3) := "c";
c(1) := 1; c(2) := 2; c(3) := 3;
% loop over the arrays %
for i := 1 until 3 do write( i_w := 1, s_w := 0, a(i), b(i), c(i) );
end. </lang>

If the arrays are not the same length, a subscript range error would occur when a non-existant element was accessed.
=={{header|AutoHotkey}}==
=={{header|AutoHotkey}}==
=== Pseudo-arrays ===
=== Pseudo-arrays ===

Revision as of 08:50, 30 August 2015

Task
Loop over multiple arrays simultaneously
You are encouraged to solve this task according to the task description, using any language you may know.

Loop over multiple arrays (or lists or tuples or whatever they're called in your language) and print the ith element of each. Use your language's "for each" loop if it has one, otherwise iterate through the collection in order with some other loop.

For this example, loop over the arrays (a,b,c), (A,B,C) and (1,2,3) to produce the output 

aA1
bB2
cC3

If possible, also describe what happens when the arrays are of different lengths.

ACL2

<lang Lisp>(defun print-lists (xs ys zs) 

  (if (or (endp xs) (endp ys) (endp zs))
      nil
      (progn$ (cw (first xs))
              (cw "~x0~x1~%"
                  (first ys)
                  (first zs))
              (print-lists (rest xs)
                           (rest ys)
                           (rest zs)))))

(print-lists '("a" "b" "c") '(A B C) '(1 2 3))</lang>

Ada

<lang Ada>with Ada.Text_IO; use Ada.Text_IO;

procedure Array_Loop_Test is 

  type Array_Index is range 1..3;
  A1 : array (Array_Index) of Character := "abc";
  A2 : array (Array_Index) of Character := "ABC";
  A3 : array (Array_Index) of Integer   := (1, 2, 3);

begin 

  for Index in Array_Index'Range loop
     Put_Line (A1 (Index) & A2 (Index) & Integer'Image (A3

(Index))(2)); 

  end loop;

end Array_Loop_Test;</lang>

ALGOL 68

Works with: ALGOL 68 version Revision 1 - no extensions to language used
Works with: ALGOL 68G version Any - tested with release

[http://sourceforge.net/projects/algol68/files/algol68g/algol68g-1.18.0/algol68g-1.18.0-9h.tiny.el5.centos.fc11.i386.rpm/download

1.18.0-9h.tiny]

<lang algol68>[]UNION(CHAR,INT) x=("a","b","c"), y=("A","B","C"), z=(1,2,3); FOR i TO UPB x DO 

 printf(($ggd$, x[i], y[i], z[i], $l$))

OD</lang>

Output:
aA1
bB2
cC3

ALGOL W

<lang algolw>begin 

   % declare the three arrays                                               %
   string(1) array a, b ( 1 :: 3 );
   integer   array c    ( 1 :: 3 );
   % initialise the arrays - have to do this element by element in Algol W  %
   a(1) := "A"; a(2) := "B"; a(3) := "C";
   b(1) := "a"; b(2) := "b"; b(3) := "c";
   c(1) :=  1;  c(2) :=  2;  c(3) :=  3;
   % loop over the arrays                                                   %
   for i := 1 until 3 do write( i_w := 1, s_w := 0, a(i), b(i), c(i) );

end. </lang>

If the arrays are not the same length, a subscript range error would occur when a non-existant element was accessed.

AutoHotkey

Pseudo-arrays

StringSplit creates a pseudo-array <lang autohotkey>List1 = a,b,c List2 = A,B,C List3 = 1,2,3 MsgBox, % LoopMultiArrays()

List1 = a,b,c,d,e List2 = A,B,C,D List3 = 1,2,3 MsgBox, % LoopMultiArrays()


---------------------------------------------------------------------------

LoopMultiArrays() 

{ ; print the ith element of each
---------------------------------------------------------------------------


   local Result
   StringSplit, List1_, List1, `,
   StringSplit, List2_, List2, `,
   StringSplit, List3_, List3, `,
   Loop, % List1_0
       Result .= List1_%A_Index% List2_%A_Index% List3_%A_Index% "`n"
   Return, Result

}</lang> An array that is too short on creation will return empty strings when trying to retrieve further elements. The 2nd Message box shows: 

aA1
bB2
cC3
dD
e

Real arrays

Works with: AutoHotkey_L

In AutoHotkey_L, we can use true arrays (Objects) and the For loop. <lang AHK>List1 := ["a", "b", "c"] List2 := ["A", "B", "C"] List3 := [ 1 , 2 , 3 ] MsgBox, % LoopMultiArrays()

List1 := ["a", "b", "c", "d", "e"] List2 := ["A", "B", "C", "D"] List3 := [1,2,3] MsgBox, % LoopMultiArrays()


LoopMultiArrays() { 

   local Result
   For key, value in List1
       Result .= value . List2[key] . List3[key] "`n"
   Return, Result

}</lang> The output from this script is identical to the first one.

AWK

<lang awk>BEGIN { 

 split("a,b,c", a, ",");
 split("A,B,C", b, ",");
 split("1,2,3", c, ",");

 for(i = 1; i <= length(a); i++) {
   print a[i] b[i] c[i];
 }

}</lang>

Axe

Note that in this example, we use a few bytes from each of L₁, L₂, and L₃ for simplicity. In practice, one would want to arrange the arrays to all fit within L₁ to avoid volatility issues with L₂ and L₃. <lang axe>'a'→{L₁} 'b'→{L₁+1} 'c'→{L₁+2} 'A'→{L₂} 'B'→{L₂+1} 'C'→{L₂+2} 1→{L₃} 2→{L₃+1} 3→{L₃+2} For(I,0,2) Disp {L₁+I}►Char,{L₂+I}►Char,{L₃+I}►Dec,i End</lang>

Babel

There are two ways to do this in Babel. First, you could transpose the lists:

<lang babel>main: { (('a' 'b' 'c')('A' 'B' 'C')('1' '2' '3')) simul_array }

simul_array!: 

   { trans
   { { << } each "\n" << } each }</lang>

The 'trans' operator substitutes nil in the portions of each transposed column wherever a row list was shorter than the longest row list. The '<<' operator prints nothing if the top-of-stack is nil.

A more literal solution to the problem as presented would be to iterate across each list using a user-defined cdrall operator:

<lang babel>main: { (('a' 'b' 'c')('A' 'B' 'C')('1' '2' '3')) simul_array }

simul_array!: 

   {{ dup 
       { car << } each 
       cdrall }
       { allnil? not }
   while }

cdrall!: { { { cdr } each -1 take } nest }

-- only returns true if all elements of a list are nil allnil?!: 

   { 1 <->
   { car nil? 
       { zap 0 last }
       { nil }
   if} each }</lang>

This solution is formally identical to the first and will handle lists of varying lengths by printing inserting nil and printing nothing for the tail ends 

of the

short lists.

BBC BASIC

<lang bbcbasic> DIM array1$(2), array2$(2), array3%(2) 

     array1$() = "a", "b", "c"
     array2$() = "A", "B", "C"
     array3%() = 1, 2, 3
     
     FOR index% = 0 TO 2
       PRINT array1$(index%) ; array2$(index%) ; array3%(index%)
     NEXT</lang>

C

Given several arrays, especially if they are heterogeneous, the most ordinary way to loop over all of them is to simply use an index variable. Determining when to stop is generally done in some application-specific way.

<lang c>#include <stdio.h>

char a1[] = {'a','b','c'}; char a2[] = {'A','B','C'}; int a3[] = {1,2,3};

int main(void) { 

   for (int i = 0; i < 3; i++) {
       printf("%c%c%i\n", a1[i], a2[i], a3[i]);
   }

}</lang>

(Note: Some compilers may require a flag to accept this modern C code, such as gcc -std=c99.)

On the other hand, it is possible to write a more generic higher-order iteration scheme, as demonstrated in this example. 

There, a type for arrays with runtime-specified lengths and polymorphic
printing is defined, and the iteration continues up to the length of

the shortest array.

C#

<lang csharp>class Program { 

   static void Main(string[] args)
   {
       char[] a = { 'a', 'b', 'c' };
       char[] b = { 'A', 'B', 'C' };
       int[] c = { 1, 2, 3 };
       int min = Math.Min(a.Length, b.Length);
       min = Math.Min(min, c.Length);
       for (int i = 0; i < min; i++)
           Console.WriteLine("{0}{1}{2}", a[i], b[i], c[i]);
   }

}</lang>


Using Zip:

<lang csharp> int[] numbers = { 1, 2, 3, 4 }; string[] words = { "one", "two", "three" }; Console.WriteLine(numbers.Zip(words, (first, second) => first + " " + 

second));

</lang>

Like a perl programmer would write it:

<lang csharp> Console.WriteLine((new[] { 1, 2, 3, 4 }).Zip(new[] { "a", "b", "c" }, (f, s) => f + " " + s)); </lang>

C++

With std::vectors: <lang cpp>#include <iostream>

  1. include <vector>

int main(int argc, char* argv[]) { 

  std::vector<char> ls(3); ls[0] = 'a'; ls[1] = 'b'; ls[2] = 'c';
  std::vector<char> us(3); us[0] = 'A'; us[1] = 'B'; us[2] = 'C';
  std::vector<int> ns(3);  ns[0] = 1;   ns[1] = 2;   ns[2] = 3;

  std::vector<char>::const_iterator lIt = ls.begin();
  std::vector<char>::const_iterator uIt = us.begin();
  std::vector<int>::const_iterator nIt = ns.begin();
  for(; lIt != ls.end() && uIt != us.end() && nIt !=

ns.end(); 

      ++lIt, ++uIt, ++nIt)
  {
     std::cout << *lIt << *uIt << *nIt << "\n";
  }

}</lang>

Using static arrays: <lang cpp>#include <iostream>

int main(int argc, char* argv[]) { 

  char ls[] = {'a', 'b', 'c'};
  char us[] = {'A', 'B', 'C'};
  int ns[] = {1, 2, 3};

  for(size_t li = 0, ui = 0, ni = 0;
      li < sizeof(ls) && ui < sizeof(us) && ni

< sizeof(ns) / sizeof(int); 

      ++li, ++ui, ++ni)
  {
     std::cout << ls[li] << us[ui] << ns[ni] <<
"\n";
  }

}</lang>

Chapel

<lang chapel>var a1 = [ "a", "b", "c" ]; var a2 = [ "A", "B", "C" ]; var a3 = [ 1, 2, 3 ];

for (x,y,z) in zip(a1, a2, a3) do 

   writeln(x,y,z);</lang>

Clojure

<lang clojure>(doseq [s (map #(str %1 %2 %3) "abc" "ABC" "123")] 

 (println s))</lang>

The sequence stops when the shortest list is exhausted.

COBOL

<lang cobol> IDENTIFICATION DIVISION. 

      PROGRAM-ID. Loop-Over-Multiple-Tables.

      DATA DIVISION.
      WORKING-STORAGE SECTION.
      01  A VALUE "abc".
          03  A-Vals PIC X OCCURS 3 TIMES.

      01  B VALUE "ABC".
          03  B-Vals PIC X OCCURS 3 TIMES.

      01  C VALUE "123".
          03  C-Vals PIC 9 OCCURS 3 TIMES.

      01  I PIC 9.

      PROCEDURE DIVISION.
          PERFORM VARYING I FROM 1 BY 1 UNTIL 3 < I
              DISPLAY A-Vals (I) B-Vals (I) C-Vals (I)
          END-PERFORM

          GOBACK
          .</lang>

Common Lisp

Using functional application

<lang lisp>(mapc (lambda (&rest args) 

       (format t "~{~A~}~%" args))
     '(|a| |b| |c|)
     '(a b c)
     '(1 2 3))</lang>

If lists are different lengths, it stops after the shortest one.

Using LOOP

<lang lisp> 

 (loop for x in '("a" "b" "c")
       for y in '(a b c)
       for z in '(1 2 3)
       do (format t "~a~a~a~%" x y z))

</lang>

D

<lang d>import std.stdio, std.range;

void main () { 

   foreach (a, b, c; zip("abc", "ABC", [1, 2, 3]))
       writeln(a, b, c);

}</lang>

Output:
aA1
bB2
cC3

zip() allows to specify the stopping policy. On default it stops when the shortest range is exhausted (same as StoppingPolicy.shortest): <lang d>import std.stdio, std.range;

void main () { 

   auto a1 = [1, 2];
   auto a2 = [1, 2, 3];
   alias StoppingPolicy sp;

   // Stops when the shortest range is exhausted
   foreach (p; zip(sp.shortest, a1, a2))
       writeln(p.tupleof);
   writeln();

   // Stops when the longest range is exhausted
   foreach (p; zip(sp.longest, a1, a2))
       writeln(p.tupleof);
   writeln();

   // Requires that all ranges are equal
   foreach (p; zip(sp.requireSameLength, a1, a2))
       writeln(p.tupleof);

}</lang>

Output:
11
22

11
22
03

11
22

Followed by an exception with message "Inequal-length ranges passed to Zip".

There is also std.range.lockstep: <lang d>import std.stdio, std.range;

void main() { 

   auto arr1 = [1, 2, 3, 4, 5];
   auto arr2 = [6, 7, 8, 9, 10];

   foreach (ref a, ref b; lockstep(arr1, arr2))
       a += b;

   assert(arr1 == [7, 9, 11, 13, 15]);

   // Lockstep also supports iteration with an index variable
   foreach (index, a, b; lockstep(arr1, arr2))
       writefln("Index %s:  a = %s, b = %s", index, a, b);

}</lang> Lower level code that stops at the shortest length: <lang d>import std.stdio, std.algorithm;

void main () { 

   auto s1 = "abc";
   auto s2 = "ABC";
   auto a1 = [1, 2];

   foreach (i; 0 .. min(s1.length, s2.length, a1.length))
       writeln(s1[i], s2[i], a1[i]);

}</lang>

Output:
aA1
bB2

Delphi

<lang Delphi>program LoopOverArrays;

{$APPTYPE CONSOLE}

uses SysUtils;

const 

 ARRAY1: array [1..3] of string = ('a', 'b', 'c');
 ARRAY2: array [1..3] of string = ('A', 'B', 'C');
 ARRAY3: array [1..3] of Integer = (1, 2, 3);

var 

 i: Integer;

begin 

 for i := 1 to 3 do
   Writeln(Format('%s%s%d', [ARRAY1[i], ARRAY2[i], ARRAY3[i]]));

 Readln;

end.</lang>

DWScript

If the arrays don't have the same bounds, an index out of bound exception will be triggered when attempting to access a non-existing element.

<lang delphi>const a1 = ['a', 'b', 'c']; const a2 = ['A', 'B', 'C']; const a3 = [1, 2, 3];

var i : Integer; for i := 0 to 2 do 

  PrintLn(Format('%s%s%d', [a1[i], a2[i], a3[i]]));</lang>

E

E lacks a nice way to do this; this is [http://wiki.erights.org/wiki/Parallel_iteration to be fixed, once we figure out what to do]. However, iteration over an List produces its indexes as keys, so a not entirely awful idiom exists:

<lang e>def a1 := ["a","b","c"] def a2 := ["A","B","C"] def a3 := ["1","2","3"]

for i => v1 in a1 { 

   println(v1, a2[i], a3[i])

}</lang>

This will obviously fail if a2 or a3 are shorter than a1, and omit items 

if a2 or a3 are longer.

Given a parallel iteration utility, we might write this:

<lang e>for [v1, v2, v3] in zip(a1, a2, a3) { 

   println(v1, v2, v3)

}</lang>

zip cannot yet be defined for all collections (other than by iterating over each one and storing the results in a List 

first); but we can define it for numeric-indexed collections such as

Lists, as below. Both a definition for any number of collections and two 

collections is given; the latter in order to demonstrate the principle

without the clutter resulting from handling a variable number of collections.

<lang e>def zip { 

 to run(l1, l2) {
   def zipped {
     to iterate(f) {
       for i in int >= 0 {
         f(i, [l1.fetch(i, fn { return }),
               l2.fetch(i, fn { return })])
       }
     }
   }
   return zipped
 }

 match [`run`, lists] {
   def zipped {
     to iterate(f) {
       for i in int >= 0 {
         var tuple := []
         for l in lists {
           tuple with= l.fetch(i, fn { return })
         }
         f(i, tuple)
       }
     }
   }
   zipped
 }

}</lang>

(This will stop when the end of the shortest collection is reached.)

Efene

<lang efene>@public run = fn () { 

   lists.foreach(fn ((A, B, C)) { io.format("~s~n", A, B, C) },

lists.zip3("abc", "ABC", "123")) } </lang>

If the lists are not all the same length, an error is thrown.

Ela

<lang ela>open console list imperative

xs = zipWith3 (\x y z -> show x ++ show y ++ show z) ['a','b','c'] ['A','B','C'] [1,2,3]

each writen xs</lang>

The code above can be written shorter. First there is no need in lists as soon as strings in Ela can be treated as lists. Also instead of explicit labmda one can use partial application and a standard composition operator:

<lang ela>xs = zipWith3 (\x -> (x++) >> (++)) "abc" "ABC" 

"123"</lang>

Elixir

string list: <lang elixir>l1 = ["a", "b", "c"] l2 = ["A", "B", "C"] l3 = ["1", "2", "3"] IO.inspect List.zip([l1,l2,l3]) |> Enum.map(fn x-> Tuple.to_list(x) |> Enum.join end)

  1. => ["aA1", "bB2", "cC3"]</lang>

char_list: <lang elixir>l1 = 'abc' l2 = 'ABC' l3 = '123' IO.inspect List.zip([l1,l2,l3]) |> Enum.map(fn x-> Tuple.to_list(x) end)

  1. => ['aA1', 'bB2', 'cC3']</lang>

When the length of the list is different: <lang elixir>iex(1)> List.zip(['abc','ABCD','12345']) |> Enum.map(&Tuple.to_list(&1)) ['aA1', 'bB2', 'cC3'] iex(2)> List.zip(['abcde','ABC','12']) |> Enum.map(&Tuple.to_list(&1)) ['aA1', 'bB2']</lang> The zipping finishes as soon as any enumerable completes.

Erlang

Shortest option: <lang erlang>lists:zipwith3(fun(A,B,C)-> io:format("~s~n",A,B,C) end, "abc", "ABC", "123").</lang> However, as every expression in Erlang has to return something, printing 

text returns 'ok'. A list with as many 'ok's as there are lines printed
will thus be created.

The technically cleanest way to do things would be with lists:foreach/2, which also guarantees evaluation order: <lang erlang>lists:foreach(fun({A,B,C}) -> io:format("~s~n",A,B,C) end, 

             lists:zip3("abc", "ABC", "123")).</lang>

If the lists are not all the same length, an error is thrown.

Euphoria

There are many ways to do this. All of them rely on what strings really 

are.

If they are all "strings", it's quite easy: <lang Euphoria> sequence a, b, c

a = "abc" b = "ABC" c = "123"

for i = 1 to length(a) do 

   puts(1, a[i] & b[i] & c[i] & "\n")

end for </lang>

If not, and the other sequence is known to contain only integers:

<lang Euphoria> sequence a, b, c

a = "abc" b = "ABC" c = {1, 2, 3}

for i = 1 to length(a) do 

   printf(1, "%s%s%g\n", {a[i], b[i], c[i]})

end for </lang>

A general solution for any arbitrary strings of characters or numbers can get a bit complex. This is because of how sequences are stored and printed out. One possible answer is as follows, if you know that only alphanumeric characters are used: <lang Euphoria> for i = 1 to length(a) do 

   if (a[i] >= '0' and a[i] <= '9') then

a[i] -= '0' 

   end if
   if (b[i] >= '0' and b[i] <= '9') then

b[i] -= '0' 

   end if
   if (c[i] >= '0' and c[i] <= '9') then

c[i] -= '0' 

   end if
   printf(1, "%s%s%s\n", {a[i], b[i], c[i]})

end for </lang> Just as in Java, using single quotes around a character gives you its "char value". In Euphoria, though, it is simply that character's code in ASCII.

With all three of the above solutions, if any of the strings are smaller 

than the first, it will return an error.

F#

<lang fsharp>for c1,c2,n in Seq.zip3 ['a';'b';'c'] ['A';'B';'C'] [1;2;3] do 

 printfn "%c%c%d" c1 c2 n</lang>

When one sequence is exhausted, any remaining elements in the other sequences are ignored.

Factor

<lang factor>"abc" "ABC" "123" [ [ write1 ] tri@ nl ] 3each</lang>

Fantom

This will stop when it reaches the end of the shortest list. <lang fantom> class LoopMultiple { 

 public static Void main ()
 {
   List arr1 := ["a", "b", "c"]
   List arr2 := ["A", "B", "C"]
   List arr3 := [1, 2, 3]
   [arr1.size, arr2.size, arr3.size].min.times |Int i|
   {
     echo ("${arr1[i]}${arr2[i]}${arr3[i]}")
   }
 }

} </lang>

Forth

<lang forth>create a char a , char b , char c , create b char A , char B , char C , create c char 1 , char 2 , char 3 ,

main
 3 0 do cr
   a i cells + @ emit
   b i cells + @ emit
   c i cells + @ emit
 loop
 cr
 a b c
 3 0 do cr
   3 0 do
     rot dup @ emit cell+
   loop
 loop
 drop drop drop
</lang>

Fortran

<lang fortran>program main 

implicit none

integer,parameter :: n_vals = 3
character(len=*),dimension(n_vals),parameter :: ls = ['a','b','c']
character(len=*),dimension(n_vals),parameter :: us = ['A','B','C']
integer,dimension(n_vals),parameter          :: ns = [1,2,3]

integer :: i  !counter

do i=1,n_vals
     write(*,'(A1,A1,I1)') ls(i),us(i),ns(i)
end do

end program main </lang>

FunL

<lang funl>import lists.zip3

for x <- zip3( ['a', 'b', 'c'], ['A', 'B', 'C'], [1, 2, 3] ) 

   println( x.mkString() )</lang>
Output:
aA1
bB2
cC3

GAP

<lang gap>

  1. The Loop function will apply some function to every tuple built by

taking

  1. the i-th element of each list. If one of them is exhausted before the

others,

  1. the loop continues at its begining. Only the longests lists will be

precessed only once. Loop := function(a, f) 

   local i, j, m, n, v;
   n := Length(a);
   v := List(a, Length);
   m := Maximum(v);
   for j in [1 .. m] do
       f(List([1 .. n], i -> a[i][1 + RemInt(j - 1, v[i])]));
   od;

end;

  1. Here we simply print each "row"

f := function(u) 

   Perform(u, Print);
   Print("\n");

end;

Loop([["a", "b", "c"], ["A", "B", "C"], [1, 2, 3]], f);

aA1 bB2 cC3

Loop([["a", "b"], ["A", "B", "C", "D", "E"], [1, 2, 3]], f);

aA1 bB2 aC3 bD1 aE2</lang>

Go

Go's "range clause" of a for statement only looks at a single iterable value (array, slice, etc). To access the three in parallel, they have to be explicitly indexed.

If a2 or a3 were shorter, the program would panic with "runtime error: index out of range". If a2 or a3 were longer, extra elements would be ignored. Go's philosophy is that you should explicitly check for whatever conditions are meaningful in your application and explicitly handle whatever errors are plausible. <lang go>package main

import "fmt"

var a1 = []string{"a", "b", "c"} var a2 = []byte{'A', 'B', 'C'} var a3 = []int{1, 2, 3}

func main() { for i := range a1 { fmt.Printf("%v%c%v\n", a1[i], a2[i], a3[i]) } }</lang>

Golfscript

<lang golfscript>["a" "b" "c"]:a; ["A" "B" "C"]:b; ["1" "2" "3"]:c; [a b c]zip{puts}/</lang>

If there are arrays of different size, the shorter are treated as "null-padded" array.

Groovy

Solution: <lang groovy>def synchedConcat = { a1, a2, a3 -> 

   assert a1 && a2 && a3
   assert a1.size() == a2.size()
   assert a2.size() == a3.size()
   [a1, a2, a3].transpose().collect { "${it[0]}${it[1]}${it[2]}" }

}</lang>

Test: <lang groovy>def x = ['a', 'b', 'c'] def y = ['A', 'B', 'C'] def z = [1, 2, 3]

synchedConcat(x, y, z).each { println it }</lang>

Output:
aA1
bB2
cC3

Haskell

Using list comprehension

<lang haskell>{-# LANGUAGE ParallelListComp #-} main = sequence [ putStrLn [x, y, z] | x <- "abd" | y <- "ABC" | z <- "123"]</lang>

Using Transpose

In this special case of transposing strings.

<lang haskell>import Data.List main = mapM putStrLn $ transpose ["abd", "ABC", "123"]</lang>

Using ZipWith*

<lang haskell>import Data.List main = mapM putStrLn $ zipWith3 (\a b c -> [a,b,c]) "abc" "ABC" "123"</lang>

Using applicative ZipLists

ZipLists generalize zipWith to any number of parameters <lang haskell>import Control.Applicative main = sequence $ getZipList $ (\x y z -> putStrLn [x, y, z]) <$> ZipList "abd" <*> ZipList "ABC" <*> ZipList "123"</lang>

Haxe

<lang haxe>using Lambda; using Std;

class Main {

static function main() { var a = ['a', 'b', 'c']; var b = ['A', 'B', 'C']; var c = [1, 2, 3];

//Find smallest array var len = [a, b, c] .map(function(a) return a.length) .fold(Math.min, 0x0FFFFFFF) .int();

for (i in 0...len) Sys.println(a[i] + b[i] + c[i].string()); } }</lang>

HicEst

<lang HicEst>CHARACTER :: A = "abc" REAL :: C(3)

C = $ ! 1, 2, 3

DO i = 1, 3 

  WRITE() A(i), "ABC"(i), C(i)

ENDDO</lang>

Icon and Unicon

The first solution uses co-expressions to produce parallel evaluation. <lang Icon>procedure main() a := create !["a","b","c"] b := create !["A","B","C"] c := create !["1","2","3"] while write(@a,@b,@c) end</lang>

The second solution is more like other procedural languages and also handles unequal list lengths. <lang Icon>link numbers # for max

procedure main()

a := ["a","b","c"] b := ["A","B","C","D"] c := [1,2,3]

every i := 1 to max(*a,*b,*c) do 

  write(a[i]|"","\t",b[i]|"","\t",c[i]|"")

end</lang>

Library: Icon Programming Library

[http://www.cs.arizona.edu/icon/library/procs/numbers.htm Uses max from numbers]

J

For arrays of different types: <lang J> ,.&:(":"0@>)/ 'abc' ; 'ABC' ; 1 2 3 aA1 bB2 cC3</lang> This approach works by representing the digits as characters.

Where arrays are all the same type (all numeric or all string): <lang J> ,.&:>/ 'abc' ; 'ABC' ; '123' aA1 bB2 cC3</lang>

Both of these implementations reject arrays with conflicting lengths.

Other options include:

<lang J> |: 'abc', 'ABC' ,:;":&> 1 2 3 aA1 bB2 cC3</lang> <lang J> |: 'abc', 'ABC',: '123' aA1 bB2 cC3</lang> These implementations pad short arrays with spaces.

Or:

<lang J> |:>]&.>L:_1 'abc';'ABC';<1 2 3 ┌─┬─┬─┐ │a│A│1│ ├─┼─┼─┤ │b│B│2│ ├─┼─┼─┤ │c│C│3│ └─┴─┴─┘</lang>

This implementation puts each item from each of the original lists into a box and forms an array of boxes. (A "box" is a immutable pointer to immutable data -- in other words value semantics instead of reference semantics -- and "putting an item into a box" is obtaining one of these pointers for that item.) This implementation extends any short array by providing empty boxes to represent the missing elements. (An "empty box" is what a programmer in another language might call "a pointer to a zero length array".)

Java

Translation of: JavaScript

<lang java>String[] a = {"a","b","c"}; String[] b = {"A","B","C"}; int[] c = {1,2,3}; for(int i = 0;i < a.length;i++){ 

   System.out.println(a[i] + b[i] + c[i]);

}</lang> If the first array is too short, it will stop when it gets to the end of the first array. If one of the other arrays is too short, an ArrayIndexOutOfBoundException will be thrown.

JavaScript

This loops over the indices of the first array, and uses that to index into the others. <lang javascript>var a = ["a","b","c"], 

   b = ["A","B","C"],
   c = [1,2,3],
   output = "",
   i;

for (i = 0; i < a.length; i += 1) { 

   output += a[i] + b[i] + c[i] + "\n";

}</lang> If the b or c arrays are too "short", you will see the string "undefined" appear in the output.

jq

The following solution is based on the assumption that all the arrays can be presented as an array of arrays. This allows any number of arrays to be handled.

Specifically, zip/0 expects an array of 0 or more arrays as its input. The first array determines the number of items in the output; nulls are used for padding. <lang jq># zip/0 emits [] if input is [].

def zip: 

 . as $in
 | [range(0; $in[0]|length) as $i | $in | map( .[$i] ) ];</lang>

Example 1: 

[["a","b","c"], ["A","B","C"], [1,2,3]] | zip
Output:
 [["a","A",1],["b","B",2],["c","C",3]]

To obtain the compact output used in the the task description, we can filter the results through a "pretty-print" function: 

def pp: reduce .[] as $i (""; . + "\($i)");

Example 2: 

[["a","b","c"], ["A","B","C"], [1,2,3]] | zip | map(pp)
Output:
 [
  "aA1",
  "bB2",
  "cC3"
 ]

As already mentioned, the above definition of zip/0 privileges the first 

array,

and if the subsequent arrays are of different lengths, null is used as a 

filler.

Thus: 

[["a","b","c"], ["A","B"], [1]] | zip

produces: 

[["a","A",1],["b","B",null],["c",null,null]]

Handling jagged input An alternative approach would be use a variant of zip/0 that pads all arrays shorter than the longest with nulls. Here is such a variant: <lang jq>

  1. transpose a possibly jagged matrix

def transpose: 

 if . == [] then []
 else (.[1:] | transpose) as $t
 | .[0] as $row
 | reduce range(0; [($t|length), (.[0]|length)] | max) as $i
        ([]; . + [ [ $row[$i] ] + $t[$i] ])
 end;

</lang>

Julia

With a higher order function: <lang Julia>julia> map(println, ('a','b','c'),('A','B','C'),(1,2,3)) ; aA1 bB2 cC3 </lang>

With a loop: <lang Julia>julia> for (i,j,k) in zip(('a','b','c'),('A','B','C'),(1,2,3)) 

        println(i,j,k)
      end

aA1 bB2 cC3 </lang>

K

<lang K>{,/$x}'+("abc";"ABC";1 2 3)</lang>

Output:
("aA1"
 "bB2"
 "cC3")

If the length of the arrays are different, then K croaks with "length error".

The following is a more general approach where <lang K> 

     &/#:'x

</lang>

calculates the minimum length of the arrays and is used to index the first elements in each array.

<lang K> 

  {+x[;!(&/#:'x)]}("abc";"ABC";"1234")

</lang>

Output:
("aA1"
 "bB2"
 "cC3")

If the arrays are of different type, then the arrays must be converted to strings.

<lang K> 

  {a:,/'($:'x);+a[;!(&/#:'a)]}("abc";"ABC";1 2 3 4)

</lang>

LFE

<lang lisp> (lists:zipwith3 

 (lambda (i j k)
   (io:format "~s~s~p~n" `(,i ,j ,k)))
   '(a b c)
   '(A B C)
   '(1 2 3))

</lang>

If any of the data lists differ in size from the other, the results will print out up to the shortest data list, and then raise a function_clause error.

Erlang, and thus LFE, have zipwith and zipwith3 for working with 2 and 3 simultaneous sets of data respectively. If you need more than that, you'll need to create your own "zip" function with something like (: lists map ...).

Liberty BASIC

<lang lb>a$(1)="a" : a$(2)="b" : a$(3)="c" b$(1)="A" : b$(2)="B" : b$(3)="C" c(1)=1 : c(2)=2 : c(3)=3


for i = 1 to 3 

   print a$(i);b$(i);c(i)

next</lang>

Lisaac

<lang Lisaac>Section Header

+ name := ARRAY_LOOP_TEST;

Section Public

- main <- ( 

 + a1, a2 : ARRAY[CHARACTER];
 + a3 : ARRAY[INTEGER];

 a1 := ARRAY[CHARACTER].create 1 to 3;
 a2 := ARRAY[CHARACTER].create 1 to 3;
 a3 := ARRAY[INTEGER].create 1 to 3;

 1.to 3 do { i : INTEGER;
   a1.put ((i - 1 + 'a'.code).to_character) to i;
   a2.put ((i - 1 + 'A'.code).to_character) to i;
   a3.put i to i;
 };

 1.to 3 do { i : INTEGER;
   a1.item(i).print;
   a2.item(i).print;
   a3.item(i).print;
   '\n'.print;
 };

);</lang>

LiveCode

Arrays <lang LiveCode>command loopArrays 

   local lowA, uppA, nums, z
   put "a,b,c" into lowA
   put "A,B,C" into uppA
   put "1,2,3" into nums
   
   split lowA by comma
   split uppA by comma
   split nums by comma

   repeat with n = 1 to the number of elements of lowA
       put lowA[n] & uppA[n] & nums[n] & return after z
   end repeat
   put z

end loopArrays</lang> "list" processing <lang LiveCode>command loopDelimitedList 

   local lowA, uppA, nums, z
   put "a,b,c" into lowA
   put "A,B,C" into uppA
   put "1,2,3" into nums

   repeat with n = 1 to the number of items of lowA
       put item n of lowA & item n of uppA & item n of nums

& return after z 

   end repeat
   put z

end loopDelimitedList</lang> Output - both behave similarly for this exercise. 

aA1
bB2
cC3

When there are fewer elements than the first (or whatever the loop is based on), livecode will add an "empty" value. If we add a "d" to lowA and a 4 to nums we get the following: 

aA1
bB2
cC3
d4

Works with: UCB Logo

<lang logo>show (map [(word ?1 ?2 ?3)] [a b c] [A B C] [1 2 3]) 

; [aA1 bB2 cC3]

(foreach [a b c] [A B C] [1 2 3] [print (word ?1 ?2 ?3)])  ; as above, one per line</lang>

Lua

This can be done with a simple for loop: <lang lua> a1, a2, a3 = {a , b , c } , { A , B , C } , { 1 , 2 , 3 } for i = 1, 3 do print(a1[i],a2[i],a3[i]) end </lang> but it may be more enlightening (and in line with the spirit of the challenge) to use the generic for: <lang lua> function iter(a, b, c) 

 local i = 0
 return function()
   i = i + 1
   return a[i], b[i], c[i]
 end

end

for u, v, w in iter(a1, a2, a3) do print(u, v, w) end </lang>

Mathematica

This can be done with a built-in function: <lang mathematica> MapThread[Print, {{"a", "b", "c"}, {"A", "B", "C"}, {1, 2, 3}}]; </lang> All arguments must be lists of the same length.

Mercury

<lang>

- module multi_array_loop.
- interface.
- import_module io.
- pred main(io::di, io::uo) is det.
- implementation.
- import_module char, list, string.

main(!IO) :- 

   A = ['a', 'b', 'c'],
   B = ['A', 'B', 'C'],
   C = [1, 2, 3],
   list.foldl_corresponding3(print_elems, A, B, C, !IO).
- pred print_elems(char::in, char::in, int::in, io::di, io::uo) is det.

print_elems(A, B, C, !IO) :- 

   io.format("%c%c%i\n", [c(A), c(B), i(C)], !IO).

</lang> The foldl_corresponding family of procedures all throw a software_error/1 exception if the lengths of the lists are not the same.

Modula-3

<lang modula3>MODULE MultiArray EXPORTS Main;

IMPORT IO, Fmt;

TYPE ArrIdx = [1..3];

VAR 

 arr1 := ARRAY ArrIdx OF CHAR {'a', 'b', 'c'};
 arr2 := ARRAY ArrIdx OF CHAR {'A', 'B', 'C'};
 arr3 := ARRAY ArrIdx OF INTEGER {1, 2, 3};

BEGIN 

 FOR i := FIRST(ArrIdx) TO LAST(ArrIdx) DO
   IO.Put(Fmt.Char(arr1[i]) & Fmt.Char(arr2[i]) &

Fmt.Int(arr3[i]) & "\n"); 

 END;

END MultiArray.</lang>

MUMPS

Pieces of String version <lang MUMPS> LOOPMULT 

N A,B,C,D,%
S A="a,b,c,d"
S B="A,B,C,D"
S C="1,2,3"
S D=","
F %=1:1:$L(A,",") W !,$P(A,D,%),$P(B,D,%),$P(C,D,%)
K A,B,C,D,%
Q

</lang> When there aren't enough elements, a null string will be returned from the $Piece function.

Output:
USER>d LOOPMULT^ROSETTA
 
aA1
bB2
cC3
dD

Local arrays version <lang MUMPS> LOOPMULU 

N A,B,C,D,%
S A(1)="a",A(2)="b",A(3)="c",A(4)="d"
S B(1)="A",B(2)="B",B(3)="C",B(4)="D"
S C(1)="1",C(2)="2",C(3)="3"
; will error    S %=$O(A("")) F  Q:%=""  W !,A(%),B(%),C(%) S

%=$O(A(%)) 

S %=$O(A("")) F  Q:%=""  W !,$G(A(%)),$G(B(%)),$G(C(%)) S %=$O(A(%)) 
K A,B,C,D,%

</lang>

The commented out line will throw an <UNDEFINED> error when trying 

to look up D(4). Using the $Get function as a wrapper means that if the
subscript for the array doesn't exist, a null string will be returned.

This same syntax is used for globals (permanent variables, that have a caret "^" as the first character).

Output:
USER>D LOOPMULU^ROSETTA
 
aA1
bB2
cC3
dD
USER>D LOOPMULV^ROSETTA

aA1
bB2
cC3
dD
 S %=$O(A("")) F  Q:%=""  W !,A(%),B(%),C(%) S %=$O(A(%))
                                        ^
<UNDEFINED>LOOPMULV+5^ROSETTA *C(4)

Nemerle

It "feels" better to use zip() for this, unfortunately the built in zip() only takes two lists. <lang Nemerle>using System; using System.Console;

module LoopMultiple { 

   Zip3[T1, T2, T3] (x : list[T1], y : list[T2], z : list[T3]) :

list[T1 * T2 * T3] 

   {
       |(x::xs, y::ys, z::zs) => (x, y, z)::Zip3(xs, ys, zs)
       |([], [], [])          => []
       |(_, _, [])            => throw ArgumentNullException()
       |(_, [], _)            => throw ArgumentNullException()
       |([], _, _)            => throw ArgumentNullException()
   }
   
   Main() : void
   {
       def first  = ['a', 'b', 'c'];
       def second = ["A", "B", "C"];
       def third  = [1, 2, 3];
       
       foreach ((x, y, z) in Zip3(first, second, third))
           WriteLine($"$x$y$z");
   }

}</lang>

Alternately:

Translation of: C#

<lang Nemerle>using System.Console;

module LoopMult { 

   Main() : void
   {
       def first  = array['a', 'b', 'c'];
       def second = array['A', 'B', 'C'];
       def third  = array[1, 2, 3];
       
       when (first.Length == second.Length && second.Length ==

third.Length) 

           foreach (i in [0 .. (first.Length - 1)])
               WriteLine("{0}{1}{2}", first[i], second[i], third[i]);
   }

}</lang>

NetRexx

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

say 'Using arrays' aa = ['a', 'b', 'c', 'd'] bb = ['A', 'B', 'C'] cc = [1, 2, 3, 4]

loop x_ = 0 for aa.length 

 do
   ax = aa[x_]
 catch ArrayIndexOutOfBoundsException
   ax = ' '
 end
 do
   bx = bb[x_]
 catch ArrayIndexOutOfBoundsException
   bx = ' '
 end
 do
   cx = cc[x_]
 catch ArrayIndexOutOfBoundsException
   cx = ' '
 end

 say ax || bx || cx
 end x_

say 'Using indexed strings (associative arrays)' ai = sampleData('a b c d') bi = sampleData('A B C') ci = sampleData('1 2 3 4')

loop x_ = 1 to ai[0] 

 say ai[x_] || bi[x_] || ci[x_]
 end x_

method sampleData(arg) public static returns Rexx 

 smp = ' '
 smp[0] = arg.words
 loop i_ = 1 to smp[0]
   smp[i_] = arg.word(i_)
   end i_
   
 return smp

</lang>

Output:
Using arrays
aA1
bB2
cC3
d 4
Using indexed strings (associative arrays)
aA1
bB2
cC3
d 4

NewLISP

<lang NewLISP>(map println '(a b c) '(A B C) '(1 2 3))</lang>

Nim

<lang nim>let 

 a = @['a','b','c']
 b = @["A","B","C"]
 c = @[1,2,3]

for i in 0..2: 

 echo a[i], b[i], c[i]</lang>

Oberon-2

Works with oo2c version 2 <lang oberon2> MODULE LoopMArrays; IMPORT Out; VAR x,y: ARRAY 3 OF CHAR; z: ARRAY 3 OF INTEGER;

PROCEDURE DoLoop; VAR i: INTEGER; BEGIN i := 0; WHILE i < LEN(x) DO Out.Char(x[i]);Out.Char(y[i]);Out.LongInt(z[i],0);Out.Ln; INC(i) END END DoLoop;

BEGIN x[0] := 'a';y[0] := 'A';z[0] := 1; x[1] := 'b';y[1] := 'B';z[1] := 2; x[2] := 'c';y[2] := 'C';z[2] := 3; DoLoop END LoopMArrays. </lang> Output:

aA1
bB2
cC3

Objeck

<lang objeck> class MultipleArrayAccess { 

 function : Main(args : String[]) ~ Nil {
   a := ["a", "b", "c"];
   b := ["A", "B", "C"];
   c := [1, 2, 3];
   
   each(i : a) {
     a[i]->Append(b[i]);
     a[i]->Append(c[i]);
     a[i]->PrintLine();
   };
 }

} </lang>

If the arrays are different lengths, then an out-of-bounds error will be raised.

OCaml

an immediate solution: <lang ocaml>let a1 = [| 'a'; 'b'; 'c' |] and a2 = [| 'A'; 'B'; 'C' |] and a3 = [| '1'; '2'; '3' |] ;;

Array.iteri (fun i c1 -> 

 print_char c1;
 print_char a2.(i);
 print_char a3.(i);
 print_newline()

) a1 ;;</lang>

a more generic solution could be to use a function which iterates over a list of arrays:

<lang ocaml>let n_arrays_iter ~f = function 

 | [] -> ()
 | x::xs as al ->
     let len = Array.length x in
     let b = List.for_all (fun a -> Array.length a = len) xs in
     if not b then invalid_arg "n_arrays_iter: arrays of different

length"; 

     for i = 0 to pred len do
       let ai = List.map (fun a -> a.(i)) al in
       f ai
     done</lang>

this function raises Invalid_argument exception if arrays have different 

length,

and has this signature:

<lang ocaml>val n_arrays_iter : f:('a list -> unit) -> 'a array list -> unit</lang>

how to use it with arrays a1, a2 and a3 defined before:

<lang ocaml>let () = 

 n_arrays_iter [a1; a2; a3] ~f:(fun l ->
   List.iter print_char l;
   print_newline());
</lang>

Oforth

If arrays don't have the same size, zipAll reduces to the minimum size

<lang Oforth>[ "a", "b", "c" ] [ "A", "B", "C" ] [ 1, 2, 3 ] zipAll(3) apply(#[ apply(#print) printcr ])</lang>

Output:
aA1
bB2
cC3

ooRexx

<lang ooRexx> x = .array~of("a", "b", "c") y = .array~of("A", "B", "C") z = .array~of(1, 2, 3)

loop i = 1 to x~size 

   say x[i]y[i]z[i]

end </lang>

Oz

<lang oz>for 

  I in [a b c]
  J in ['A' 'B' 'C']
  K in [1 2 3]

do 

  {System.showInfo I#J#K}

end</lang>

The loop will stop when the shortest list is exhausted.

PARI/GP

This version stops when the shortest vector is exhausted. <lang parigp>loopMultiple(V)={ 

 my(l=#V[1]);
 for(i=2,#V,l=min(l,#V[i]));
 for(i=1,#V[1],
   for(j=1,#V,
     print1(V[j][i])
   );
   print()
 )

};</lang>

This version prints blanks when a vector is exhausted. <lang parigp>loopMultiple(V)={ 

 my(l=0);
 for(i=1,#V,l=max(l,#V[i]));
 for(i=1,#V[1],
   for(j=1,#V,
     if(#V[j]<i,
       print1(" ")
     ,
       print1(V[j][i])
     )
   );
   print()
 )

};</lang>

Pascal

See Delphi

Perl

<lang perl>sub zip (&@) { 

       my $code = shift;
       my $min;
       $min = $min && $#$_ > $min ? $min : $#$_ for @_;

       for my $i(0..$min){ $code->(map $_->[$i] ,@_) }

} my @a1 = qw( a b c ); my @a2 = qw( A B C ); my @a3 = qw( 1 2 3 );

zip { print @_,"\n" }\(@a1, @a2, @a3);</lang>

This implementation will stop producing items when the shortest array ends.

Perl 6

Works with: niecza version 2011.07

<lang perl6>for <a b c> Z <A B C> Z 1, 2, 3 -> $x, $y, $z { 

  say $x, $y, $z;

}</lang>

The Z operator stops emitting items as soon as the shortest input list is exhausted. However, short lists are easily extended by replicating all or part of the list, or by appending any kind of lazy list generator to supply default values as 

necessary.

Note that we can also factor out the concatenation by making the Z metaoperator apply the ~ concatenation operator across each triple: <lang perl6>for <a b c> Z~ <A B C> Z~ 1, 2, 3 -> $line { say $line; }</lang> We could also use the zip-to-string with the reduction metaoperator: <lang perl6>.say for [Z~] [<a b c>], [<A B C>], [1,2,3]</lang>

PHP

<lang PHP>$a = array('a', 'b', 'c'); $b = array('A', 'B', 'C'); $c = array('1', '2', '3'); //These don't *have* to be strings, but it saves PHP from casting them later

if ((sizeOf($a) !== sizeOf($b)) || (sizeOf($b) !== sizeOf($c))){ 

 throw new Exception('All three arrays must be the same length');

} foreach ($a as $key => $value){ 

 echo "{$a[$key]}{$b[$key]}{$c[$key]}\n";

}</lang>

This implementation throws an exception if the arrays are not all the same length.

PicoLisp

<lang PicoLisp>(mapc prinl 

  '(a b c)
  '(A B C)
  (1 2 3) )</lang>

The length of the first argument list controls the operation. If subsequent lists are longer, their remaining values are ignored. If they are shorter, NIL is passed to the function.

PL/I

<lang PL/I> declare P(3) character (1) initial ('a', b', 'c'), 

       Q(3) character (1) initial ('A', 'B', 'C'),
       R(3) fixed decimal (1) initial (1, 2, 3);

do i = lbound(P,1) to hbound(P,1); 

  put skip edit (P(i), Q(i), R(i)) (2 A, F(1));

end; </lang>

PostScript

Library: initlib

<lang postscript> % transpose is defined in initlib like this. /transpose { 

   [ exch {
       { {empty? exch pop} map all?} {pop exit} ift
       [ exch {} {uncons {exch cons} dip exch} fold counttomark 1 roll]
uncons
   } loop ] {reverse} map

}.

% using it. [[/a /b /c] [/A /B /C] [1 2 3]] transpose </lang>

PowerBASIC

<lang powerbasic>FUNCTION PBMAIN () AS LONG 

   DIM x(2), y(2) AS STRING * 1
   DIM z(2) AS LONG

   'data
   ARRAY ASSIGN x() = ("a", "b", "c")
   ARRAY ASSIGN y() = ("A", "B", "C")
   ARRAY ASSIGN z() = (1, 2, 3)

   'set upper bound
   C& = UBOUND(x)
   IF UBOUND(y) > C& THEN C& = UBOUND(y)
   IF UBOUND(z) > C& THEN C& = UBOUND(z)

   OPEN "output.txt" FOR OUTPUT AS 1
   FOR L& = 0 TO C&
       IF L& <= UBOUND(x) THEN PRINT #1, x(L&);
       IF L& <= UBOUND(y) THEN PRINT #1, y(L&);
       IF L& <= UBOUND(z) THEN PRINT #1, TRIM$(STR$(z(L&)));
       PRINT #1,
   NEXT
   CLOSE

END FUNCTION</lang>

Prolog

Works with SWI-Prolog <lang Prolog>multiple_arrays(L1, L2, L3) :- maplist(display, L1, L2, L3).

display(A,B,C) :- writef('%s%s%s\n', [[A],[B],[C]]). </lang>

Output:
 ?- multiple_arrays("abc", "ABC", "123").
aA1
bB2
cC3
true.

 ?- multiple_arrays("abc", "AB", "123").
aA1
bB2
false.

PureBasic

<lang PureBasic>OpenConsole()

Fill arrays

Dim a.s(2) Dim b.s(2) Dim c(2) For Arrayposition = 0 To ArraySize(a()) 

 a(Arrayposition) = Chr(Asc("a") + Arrayposition)
 b(Arrayposition) = Chr(Asc("A") + Arrayposition)
 c(Arrayposition) = Arrayposition + 1

Next

loop over them

For Arrayposition = 0 To ArraySize(a()) 

 PrintN(a(Arrayposition) + b(Arrayposition) + Str(c(Arrayposition)))

Next Input() ;wait for Enter before ending</lang>

If they have different lengths there are two cases:
a() is the shortest one: Only elements up to maximum index of a() are printed
a() is bigger than another one: if exceeding index to much, program crashes,
else it may work because there is some "free space" after end of assigned array memory.
For example if a has size 4, line dD4 will also be printed. size 20 leads to an crash
This is because ReDim becomes slow if everytime there is a change to array size new memory has to be allocated.

Python

Using zip(): <lang python>>>> print ( '\n'.join(.join(x) for x in zip('abc', 'ABC', '123')) ) aA1 bB2 cC3 >>></lang> If lists are different lengths, zip() stops after the shortest one.

Using map(): <lang python>>>> print ( '\n'.join(map(lambda *x: .join(x), 'abc', 'ABC', '123')) ) aA1 bB2 cC3 >>></lang> If lists are different lengths, map() in Python 2.x 

pretends that the shorter lists were extended with

None items; map() in Python 3.x stops after the shortest one.

Using itertools.imap() (Python 2.x): <lang python>from itertools import imap

def join3(a,b,c): 

  print a+b+c

imap(join3,'abc','ABC','123')</lang> If lists are differnt lengths, imap() stops after the shortest is exhausted.

zip_longest

Python 3.X has zip_longest which fills shorter iterables with its fillvalue argument which defaults to None (similar to the behavior of map() in Python 2.x): <lang python>>>> from itertools import zip_longest >>> print ( '\n'.join(.join(x) for x in zip_longest('abc', 'ABCD', '12345', fillvalue='#')) ) aA1 bB2 cC3

  1. D4
    1. 5

>>></lang> (The Python 2.X equivalent is itertools.izip_longest)

R

<lang R>multiloop <- function(...) { 

  # Retrieve inputs and convert to a list of character strings
  arguments <- lapply(list(...), as.character)
  
  # Get length of each input
  lengths <- sapply(arguments, length)

  # Loop over elements
  for(i in seq_len(max(lengths)))
  {
     # Loop over inputs
     for(j in seq_len(nargs()))
     {
        # print a value or a space (if that input has finished)
        cat(ifelse(i <= lengths[j], argumentsj[i], " "))
     }
     cat("\n")
  }

} multiloop(letters[1:3], LETTERS[1:3], 1:3)</lang>

Same thing as a single function call. But throws error if the arrays differ in length.

<lang R> apply(data.frame(letters[1:3], LETTERS[1:3], 1:3), 1, 

     function(row) { cat(row, "\n", sep=) })

</lang>

Racket

Racket for loops can loop over an arbitrary number of sequences of any kind at once:

<lang racket>

  1. lang racket

(for ([x '(a b c)] ; list 

     [y #(A B C)] ; vector
     [z "123"]
     [i (in-naturals 1)]) ; 1, 2, ... infinitely
 (printf "~s: ~s ~s ~s\n" i x y z))

</lang>

The loop stops as soon as the first sequence terminates -- in the above case i</ii> can iterate forever but looping stops when we reach the end of the list/vector/string. (The same holds for multiple containers of different sizes.)

REXX

same size arrays

If any of the array's elements are missing or it is a short list, a blank is substituted to retain visual fidelity in the output.

When all elements are blank, then it signifies the end of the arrays. <lang rexx>/*REXX program shows how to simultaneously loop over 

multiple arrays.*/

x. = ' '; x.1 = "a"; x.2 = 'b'; x.3 = "c" y. = ' '; y.1 = "A"; y.2 = 'B'; y.3 = "C" z. = ' '; z.1 = "1"; z.2 = '2'; z.3 = "3" 

          do j=1  until output=
          output = x.j || y.j || z.j
          say output
          end    /*j*/                /*stick a fork in it, we're

done.*/</lang>

Output:
aA1
bB2
cC3

dissimilar sized arrays

In this example, two of the arrays are extended (past the 1st example).
Also note that REXX doesn't require quotes around numbers (they're optional). <lang rexx>/*REXX program shows how to simultaneously loop over 

multiple arrays.*/

x.=' '; x.1="a"; x.2='b'; x.3="c"; x.4='d' y.=' '; y.1="A"; y.2='B'; y.3="C"; z.=' '; z.1= 1 ; z.2= 2 ; z.3= 3 ; z.4= 4; z.5= 

5

      do j=1  until output=
      output=x.j || y.j || z.j
      say output
      end   /*j*/                     /*stick a fork in it, we're

done.*/</lang>

Output:
aA1
bB2
cC3
d 4
  5

dissimilar sized lists

<lang rexx>/*REXX program shows how to simultaneously loop over 

multiple  lists.*/

x = 'a b c d' y = 'A B C' z = 1 2 3 4 

              do j=1  until  output=
              output = word(x,j) || word(y,j) || word(z,j)
              say output
              end    /*j*/            /*stick a fork in it, we're

done.*/</lang>

Output:
aA1
bB2
cC3
d4

idiomatic method for lists

<lang rexx>/*REXX program shows how to simultaneously loop over 

multiple  lists.*/

x = 'a b c d' y = 'A B C' z = 1 2 3 4 ..LAST 

                    do j=1  for max(words(x), words(y), words(z))
                    say word(x,j) || word(y,j) || word(z,j)
                    end    /*j*/      /*stick a fork in it, we're

done.*/</lang>

Output:
aA1
bB2
cC3
d4
..LAST

Ruby

<lang ruby>['a','b','c'].zip(['A','B','C'], [1,2,3]) {|i,j,k| puts "#{i}#{j}#{k}"}</lang> or <lang ruby>['a','b','c'].zip(['A','B','C'], [1,2,3]) {|a| puts a.join}</lang>

Both of these loops print aA1, bB2, cC3.

Array#zip iterates once for each element of the receiver. If an argument array is longer, the excess elements are ignored. If an argument array is shorter, the value nil is supplied. <lang ruby>irb(main):001:0> ['a','b','c'].zip(['A','B'], [1,2,3,4]) {|a| puts a.join} aA1 bB2 c3 => nil irb(main):002:0> ['a','b','c'].zip(['A','B'], [1,2,3,4]) => [["a", "A", 1], ["b", "B", 2], ["c", nil, 3]]</lang>

Run BASIC

<lang runbasic>for i = 1 to 3 

a$(i) = chr$(i+96)
b$(i) = chr$(i+64)
c(i)  = i

next i

for i = 1 to 3 

   print a$(i);b$(i);c(i)

next</lang>

Rust

<lang rust>// rust 0.9-pre

fn main() { 

   let a1 = ["a", "b", "c"];
   let a2 = ["A", "B", "C"];
   let a3 = [1, 2, 3];

   for ((&x, &y), &z) in

a1.iter().zip(a2.iter()).zip(a3.iter()) { 

       println!("{}{}{}", x, y, z);
   }

}</lang>

Output:
aA1
bB2
cC3

Salmon

<lang Salmon>// First, we'll define a general-purpose zip() to zip 

any

// number of lists together. function zip(...) 

 {
   variable result;
   variable list_num := 0;
   iterate(arg; arguments)
     {
       variable elem_num := 0;
       iterate (x; arg)
         {
           result[elem_num][list_num] := x;
           ++elem_num;
         };
       ++list_num;
     };
   return result;
 };

immutable a := ["a", "b", "c"], 

         b := ["A", "B", "C"],
         c := [1, 2, 3];

iterate (x; zip(a, b, c)) 

   print(x[0], x[1], x[2], "\n");;</lang>

The preceding code will throw an exception if the lists aren't the same length. Here's an example that will print a number of lines equal to the length of the longest list and print nothing for elements that are missing if some lists are shorter than the longest:

<lang Salmon>// First, we'll define a general-purpose zip() to zip 

any

// number of lists together. function zip(...) 

 {
   variable result := [];
   variable list_num := 0;
   iterate(arg; arguments)
     {
       variable elem_num := 0;
       iterate (x; arg)
         {
           if (elem_num >= length(result))
               result[elem_num] := <<(* --> "")>>;;
           result[elem_num][list_num] := x;
           ++elem_num;
         };
       ++list_num;
     };
   return result;
 };

immutable a := ["a", "b", "c"], 

         b := ["A", "B", "C"],
         c := [1, 2, 3];

iterate (x; zip(a, b, c)) 

   print(x[0], x[1], x[2], "\n");;</lang>

Sather

<lang sather>class MAIN is 

 main is
   a :ARRAY{STR} := |"a", "b", "c"|;
   b :ARRAY{STR} := |"A", "B", "C"|;
   c :ARRAY{STR} := |"1", "2", "3"|;
   loop i ::= 0.upto!(2);
     #OUT + a[i] + b[i] + c[i] + "\n";
   end;
 end;

end;</lang>

If the index i is out of bounds, a runtime error is raised.

Scala

<lang scala> ("abc", "ABC", "123").zipped foreach { (x, y, z) => 

 println(x.toString + y + z)

} </lang>

Scheme

Scheme provides for-each and map to iterate a function over one or more lists. The map form is used to collect the results into a new list.

<lang scheme> (let ((a '("a" "b" "c")) 

     (b '("A" "B" "C"))
     (c '(1 2 3)))
 (for-each 
   (lambda (i1 i2 i3) 
     (display i1) 
     (display i2) 
     (display i3) 
     (newline))
   a b c))

</lang>

Scheme has a vector datatype with constant-time 

retrieval of items held in an ordered sequence.  Use srfi-43 to get

similar iterators for vectors, vector-for-each and vector-map:

<lang scheme> (let ((a (vector "a" "b" "c")) 

     (b (vector "A" "B" "C"))
     (c (vector 1 2 3)))
 (vector-for-each
   (lambda (current-index i1 i2 i3)
     (display i1) 
     (display i2) 
     (display i3) 
     (newline))
   a b c))

</lang>

Note, the lists or vectors must all be of the same length.

Sidef

The simplest way is to use MultiArrays: <lang ruby>MultiArray.new(%w(a b c),%w(A B C),%w(1 2 3)).each { |i,j,k| 

   say "#{i}#{j}#{k}";

};</lang>

Another approach is to zip two arrays at a time and reduce pairs of their elements into one element. <lang ruby>func multi_zip(zipped) { 

   .each { |arr|
       zipped.zip!(arr).reducePairs!{.flatten};
   };
   return zipped;

}

multi_zip(%w(a b c),%w(A B C),%w(1 2 3)).each{ |i,j,k| 

   say "#{i}#{j}#{k}";

};</lang> The returned array will have the same number of elements as the shortest 

array.

Smalltalk

Works with: GNU Smalltalk

<lang smalltalk>|a b c| a := OrderedCollection new addAll: #('a' 'b' 'c'). b := OrderedCollection new addAll: #('A' 'B' 'C'). c := OrderedCollection new addAll: #(1 2 3).

1 to: (a size) do: [ :i | 

 (a at: i) display.
 (b at: i) display.
 (c at: i) displayNl.

].</lang>

If index i is out of bound, a runtime error is raised.

Standard ML

The below code will combine arbitrarily many lists of strings into a single list with length equal to that of the shortest list. <lang Standard ML> (* 

* val combine_lists : string list list -> string list
*)

fun combine_lists nil = nil | combine_lists (l1::ls) = List.foldl (ListPair.map (fn (x,y) => y ^ 

x)) l1 ls;

(* ["a1Ax","b2By","c3Cz"] *) combine_lists[["a","b","c"],["1","2","3"],["A","B","C"],["x","y","z"]]; </lang>

SuperCollider

<lang SuperCollider>([\a,\b,\c]+++[\A,\B,\C]+++[1,2,3]).do({|array| array.do(_.post); "".postln })</lang>

Swift

<lang Swift>let a1 = ["a", "b", "c"] let a2 = ["A", "B", "C"] let a3 = [1, 2, 3]

for i in 0 ..< a1.count { 

   println("\(a1[i])\(a2[i])\(a3[i])")

}</lang>

Output:
aA1
bB2
cC3

Tcl

<lang tcl>set list1 {a b c} set list2 {A B C} set list3 {1 2 3} foreach i $list1 j $list2 k $list3 { 

   puts "$i$j$k"

}</lang> If lists are different lengths, the manual [1] says: "The total number of loop iterations is large enough to use up all the values from all the value lists. If a value list does not contain enough elements for each of its loop variables in each iteration, empty values are used for the missing elements."

TorqueScript

<lang Torquescript> $var[0] = "a b c" $var[1] = "A B C"; $var[2] = "1 2 3";

for(%i=0;%i<3;%i++) echo(getWord($var[0],%i) @ getWord($var[1],%i) @ getWord($var[2],%i)); </lang>

TUSCRIPT

<lang tuscript> $$ MODE TUSCRIPT arr1="a'b'c" arr2="a'b'C" arr3="1'2'3" LOOP a=arr1,b=arr2,c=arr3 PRINT a,b,c ENDLOOP </lang>

Output:
aa1
bb2
cC3

TXR

Pattern language

<lang bash>$ txr -c '@(bind a ("a" "b" "c")) @(bind b ("A" "B" "C")) @(bind c ("1" "2" "3")) @(output) @ (repeat) @a@b@c @ (end) @(end)' aA1 bB2 cC3</lang>

TXR Lisp, using mapcar

Here we actually loop over four things: three strings and an infinite list of newlines. The output is built up as one string object that is finally printed in one go.

<lang bash>$ txr -e '(pprint (mappend (op list) "abc" "ABC" "123" (repeat "\n"))))' aA1 bB2 cC3</lang>

TXR Lisp, using each

<lang bash>$ txr -e '(each ((x "abc") (y "ABC") (z "123")) (put-line `@x@y@z`))' aA1 bB2 cC3</lang>

Translation of Scheme

Translation of: Scheme

No "srfi-43" required:

<lang txr>@(do 

  ;; Scheme's vector-for-each: a one-liner in TXR
  ;; that happily works over strings and lists.
  (defun vector-for-each (fun . vecs)
    [apply mapcar fun (range) vecs])
  
  (defun display (obj : (stream *stdout*))
    (pprint obj stream))
  
  (defun newline (: (stream *stdout*))
    (display #\newline stream))
  
  (let ((a (vec "a" "b" "c"))
        (b (vec "A" "B" "C"))
        (c (vec 1 2 3)))
    (vector-for-each
      (lambda (current-index i1 i2 i3)
        (display i1)
        (display i2)
        (display i3)
        (newline))
      a b c)))</lang>

Translation of: Logo

<lang txr>@(do 

  (macro-time 
    (defun question-var-to-meta-num (var)
      ^(sys:var ,(int-str (cdr (symbol-name var))))))

  (defmacro map (square-fun . square-args)
    (tree-bind [(fun . args)] square-fun
      ^[apply mapcar (op ,fun ,*[mapcar question-var-to-meta-num args])
              (macrolet ([(. args) ^(quote ,args)])
                 (list ,*square-args))]))

  (defun word (. items)
    [apply format nil "~a~a~a" items])

  (defun show (x) (pprinl x))

  (show (map [(word ?1 ?2 ?3)] [a b c] [A B C] [1 2 3])))</lang>
Output:
(aA1 bB2 cC3)

UNIX Shell

With the Bourne shell, its for loop (from Loops/Foreach#UNIX Shell) can iterate only one list. We use an index i to access the other lists: set -- $list loads the positional parameters, and shift $i moves our element to $1.

Works with: Bourne Shell

<lang bash>a=a:b:c b=A:B:C c=1:2:3

oldifs=$IFS IFS=: i=0 for wa in $a; do set -- $b; shift $i; wb=$1 set -- $c; shift $i; wc=$1

printf '%s%s%s\n' $wa $wb $wc

i=`expr $i + 1` done IFS=$oldifs</lang>

Output:
aA1
bB2
cC3

When the lists have different lengths, this code uses the length of list 

a. Longer lists ignore their extra elements,

and shorter lists give extra empty strings.

Inspired by the previous example, below is the way to loop over two arrays simultaneously using set -- $ARGS. It is less general than the previous example but it is shorter and works just fine.

Works with: Bourne Shell

<lang bash>A='a1 a2 a3' B='b1 b2 b3'

set -- $B for a in $A do 

   printf "$a $1\n"
   shift

done</lang>

Output:
a1 b1
a2 b2
a3 b3


Some shells have real arrays, so the iteration is much more simple and easy.

Works with: bash
Works with: ksh93

<lang bash>a=(a b c) b=(A B C) c=(1 2 3) for ((i = 0; i < ${#a[@]}; i++)); do 

 echo "${a[$i]}${b[$i]}${c[$i]}"

done</lang>

Output:
aA1
bB2
cC3
Works with: ksh93
Works with: pdksh

<lang bash>set -A a a b c set -A b A B C set -A c 1 2 3 ((i = 0)) while ((i < ${#a[@]})); do 

 echo "${a[$i]}${b[$i]}${c[$i]}"
 ((i++))

done</lang>

Works with: zsh

<lang bash>a=(a b c) b=(A B C) c=(1 2 3) for ((i = 1; i <= $#a; i++)); do 

 echo "$a[$i]$b[$i]$c[$i]"

done</lang>

C Shell

Uses the length of array a. Longer arrays ignore their extra elements, but shorter arrays force the shell to exit with an error like b: Subscript out of range.

<lang csh>set a=(a b c) set b=(A B C) set c=(1 2 3) @ i = 1 while ( $i <= $#a ) echo "$a[$i]$b[$i]$c[$i]" @ i += 1 end</lang>

Ursala

Compute the transpose of the list formed of the three lists. If they're of unequal lengths, an exception occurs. <lang Ursala>#show+

main = ~&K7 <'abc','ABC','123'></lang>

Output:
aA1
bB2
cC3

Wart

<lang wart>each (x X n) (zip '(a b c) '(A B C) '(1 2 3)) 

 prn x X n</lang>

XPL0

<lang XPL0>string 0; \use zero terminated strings include c:\cxpl\codes; \intrinsic 'code' declarations char A1, A2; int A3, I; [A1:= "abc"; 

A2:= "ABC";
A3:= [1,2,3];
for I:= 0 to 2 do
       [ChOut(0, A1(I));
        ChOut(0, A2(I));
       IntOut(0, A3(I));
       CrLf(0);
       ];

]</lang>

Output:
aA1
bB2
cC3

zkl

<lang zkl>foreach a,b,c in (["a".."c"].zip(T("A","B","C"),[1..])){ println(a,b,c) }</lang> or <lang zkl>Utils.zipWith(False,fcn{vm.arglist.concat().println()}, 

  ["a".."c"],T("A","B","C"),[1..])</lang>
Output:
aA1
bB2
cC3

zip[With] stops at the end of the shortest sequence, which means it can work with infinite sequences

ZX Spectrum Basic

<lang zxbasic>10 LET sza = 3: REM size of a 20 LET szb = 3: REM size of b 30 LET szc = 3: REM size of c 40 DIM a$(sza): DIM b$(szb): DIM c$(szc) 50 LET max = sza: REM assume a is the biggest 60 IF szb > max THEN LET max = szb: REM now try b 70 IF szc > max THEN LET max = szc: REM or c 80 REM populate our arrays, and as a bonus we already have our demo loop 90 REM we might as well print as we populate showing the arrays in columns 100 FOR l = 1 TO max 110 IF l <= sza THEN READ a$(l): PRINT a$(l); 120 IF l <= szb THEN READ b$(l): PRINT b$(l); 130 IF l <= szc THEN READ c$(l): PRINT c$(l); 140 PRINT: REM newline 150 NEXT l 150 PRINT "The arrays are shown in columns." 160 PRINT "A$ runs down the left hand side," 170 PRINT "and C$ runs down the right." 180 STOP 200 DATA "a","b","c","A","B","C","1","2","3"</lang>

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