Creating an Array

Creating an Array
You are encouraged to solve this task according to the task description, using any language you may know.

This task is about numeric arrays. For hashes or associative arrays, please see Creating an Associative Array.

In this task, the goal is to create an array. Mention if the array base begins at a number other than zero.

ActionScript

<lang actionscript> // ActionScript arrays are zero-based // // creates an empty array var arr1:Array = new Array(); // creates an array with 3 numerical values var arr2:Array = new Array(1,2,3); // // or just use the shorthand var u:Array = []; var v:Array = [1,2,3]; </lang>

Ada

Compiler: GCC 4.1.2

Ada array indices may begin at any value, not just 0 or 1 <lang ada>

type Arr is array (Integer range <>) of Integer;
Uninitialized : Arr (1 .. 10);
Initialized_1 : Arr (1 .. 20) := (others => 1);
Initialized_2 : Arr := (1 .. 30 => 2);
Const         : constant Arr := (1 .. 10 => 1, 11 .. 20 => 2, 21 | 22 => 3);
Centered      : Arr (-50..50) := (0 => 1, Others => 0);

</lang> Ada arrays may be indexed by enumerated types, which are discrete non-numeric types <lang ada>

type Days is (Mon, Tue, Wed, Thu, Fri, Sat, Sun);
type Activities is (Work, Fish);
type Daily_Activities is array(Days) of Activities;
This_Week : Daily_Activities := (Mon..Fri => Work, Others => Fish);

</lang>

ALGOL 68

As with all ALGOL 68 declarations the programmer has the choice of using the full declaration syntax, or using syntactic sugar - c.f. "sugared" variables below.

Example of array of 10 integer types:

 REF []INT numbers = HEAP [1:10] INT;
 HEAP [1:10]INT sugared hnumbers; # from global memory #
 LOC [1:10]INT sugared lnumbers1; # from the stack #
 [10]INT sugared lnumbers2; # from the stack  - LOC scope is implied #

Note that the array can be taken from the heap, or stack.

Example of array of 3 string types:

 []STRING cwords = ( "these", "are", "arrays" ); # array is a constant and read-only (=) #
 [3]STRING vwords := ( "these", "are", "arrays" ); # array is a variable and modifiable (:=) #

You can also declare the size of the array and initialize the values at the same time:

 REF []INT more numbers = LOC [3]INT := ( 21, 14 ,63 );
 []INT sugared more cnumbers = ( 21, 14 ,63 );
 [3]INT sugared more vnumbers := ( 21, 14 ,63 );

For Multi-Dimensional arrays you declare them the same except for a comma in the type declaration. The following creates a 3x2 int matrix

 REF [][]INT number matrix = LOC [3][2] INT;
 [3,2]INT sugared number matrix1; # an matrix of integers #
 [3][2]INT sugared number matrix2; # an array of arrays of integers #

As with the previous examples you can also initialize the values of the array, the only difference being each row in the matrix must be enclosed in its own braces.

 [][]STRING string matrix = ( ("I","swam"), ("in","the"), ("freezing","water") );

or

 REF [][] STRING funny matrix = LOC [2][2]STRING := ( ("clowns", "are") , ("not", "funny") );
 [2][2] STRING sugared funny matrix := ( ("clowns", "are") , ("not", "funny") );

Further, the arrays can start at any number:

[-10:10] INT balanced; # for example -10 #

If the array is expected to change size in future, then the programmer can also declare it FLEX.

FLEX [-10:10] INT flex balanced;

This next piece of code creates an array of references to integers. The value of each integer "pointed at" is the square of it's index in the array.

[-10:10] REF INT array of pointers to ints;
FOR index FROM LWB array of pointers to ints TO UPB array of pointers to ints DO
  array of pointers to ints[index] :=  HEAP INT := i*i # allocate global memory #
OD

AppleScript

AppleScript arrays are called lists:

set empty to {}
set ints to {1, 2, 3}

Lists can contain any objects including other lists:

set any to {1, "foo", 2.57, missing value, ints}

Bold text

BASIC

Works with: QuickBasic version 4.5

Works with: PB version 7.1

REM Force index to start at 1..n
OPTION BASE 1

REM Force index to start at 0..n
OPTION BASE 0

REM Specify that the array is dynamic and not static
'$DYNAMIC
DIM SHARED myArray(-10 TO 10, 10 TO 30) AS STRING
REDIM SHARED myArray(20, 20) AS STRING
myArray(1,1) = "Item1"
myArray(1,2) = "Item2"

C

Works with: gcc

Works with: MSVC

Works with: BCC

Works with: Watcom

Dynamic

#include <stdlib.h> /* for malloc */
#include <string.h> /* for memset */
int n = 10 * sizeof(int);
int *myArray = (int*)malloc(n);
if(myArray != NULL)
{
  memset(myArray, 0, n);
  myArray[0] = 1;
  myArray[1] = 2;
  free(myArray);
  myArray = NULL;
}

Static

 int myArray2[10] = { 1, 2, 0}; /* 3..9 := 0 */

C++

Using dynamically-allocated (i.e. Heap) memory:

 const int n = 10;
 int* myArray = new int[n];
 if(myArray != NULL)
 {
   myArray[0] = 1;
   myArray[1] = 2;
   delete[] myArray;
   myArray = NULL;
 }

Using fixed (i.e. Stack) memory:

 int myArray2[10] = { 1, 2, 0}; /* 3..9 := 0 */

Library: STL

 // STL
 std::vector<int> myArray3(10);
 myArray3.push_back(1);
 myArray3.push_back(2);

Library: Qt

 // Qt
 QVector<int> myArray4(10);
 myArray4.push_back(1);
 myArray4.push_back(2);

Library: MFC

 // MFC
 CArray<int,int> myArray5(10);
 myArray5.Add(1);
 myArray5.Add(2);

C#

Example of array of 10 int types:

 int[] numbers = new int[10];

Example of array of 3 string types:

 string[] words = { "these", "are", "arrays" };

You can also declare the size of the array and initialize the values at the same time:

 int[] more_numbers = new int[3]{ 21, 14 ,63 };

For Multi-Dimensional arrays you declare them the same except for a comma in the type declaration.

The following creates a 3x2 int matrix

 int[,] number_matrix = new int[3,2];

As with the previous examples you can also initialize the values of the array, the only difference being each row in the matrix must be enclosed in its own braces.

 string[,] string_matrix = { {"I","swam"}, {"in","the"}, {"freezing","water"} };

or

 string[,] funny_matrix = new string[2,2]{ {"clowns", "are"} , {"not", "funny"} };

Clean

Array denotations are overloaded in Clean, therefore we explicitly specify the types. There are lazy, strict, and unboxed array.

Lazy array

Create a lazy array of strings using an array denotation.

array :: {String}
array = {"Hello", "World"}

Create a lazy array of floating point values by sharing a single element.

array :: {Real}
array = createArray 10 3.1415

Create a lazy array of integers using an array (and also a list) comprehension.

array :: {Int}
array = {x \\ x <- [1 .. 10]}

Strict array

Create a strict array of integers.

array :: {!Int}
array = {x \\ x <- [1 .. 10]}

Unboxed array

Create an unboxed array of characters, also known as String.

array :: {#Char}
array = {x \\ x <- ['a' .. 'z']}

ColdFusion

Creates a one-dimensional Array

<cfset arr1 = ArrayNew(1)>

Creates a two-dimensional Array in CFScript

<cfscript>
  arr2 = ArrayNew(2);
</cfscript>

ColdFusion Arrays are NOT zero-based, they begin at index 1

Common Lisp

Creates a one-dimensional array of length 10. The initial contents are undefined.

(make-array 10)

Creates a two-dimensional array with dimensions 10x20.

(make-array '(10 20))

make-array may be called with a number of optional arguments.

(make-array 4 :element-type 'integer :initial-contents '(1 2 3 4) :adjustable t)

D

Works with: DMD

Works with: GDC

// dynamic array
int[] numbers = new int[5];

// static array
int[5] = [0,1,2,3,4];

E

[]                 # immutable, empty
[1,9,17]           # immutable, 3 elements
[].diverge()       # mutable, empty
[].diverge(int)    # mutable, integers only

Forth

Forth has a variety of ways to allocate arrays of data, though it has no built-in array handling words, favoring pointer manipulation.

Static array of 200 cells, uninitialized:

create MyArray 200 cells allot
here MyArray - cell / constant MyArraySize

Static array containing the numbers 1 to 5

create MyArray   1 , 2 , 3 , 4 , 5 ,
here MyArray - cell / constant MyArraySize

Dynamic array allocation:

0 value MyArray
200 cells allocate throw to MyArray

Dynamic array free:

MyArray free throw
0 to MyArray

Fortran

In ANSI FORTRAN 77 or later, this is a default-indexing array declaration:

<lang fortran> integer a(10)</lang>

This array will have ten elements. Counting starts at 1.

If a zero-based array is needed, declare like this:

<lang fortran> integer a(0:9)</lang>

This mechanism can be extended to any numerical indices, and any of the up-to-seven-allowed number of dimensions (and of course to other data types than integers). For example:

<lang fortran> real a(25:29,12)</lang>

will be an two-dimensional, 5x12-array of type REAL, where the first dimension can be addressed numerically as 25, 26, 27, 28 or 29 (and the second dimension as 1 .. 12).

Fortran 90 and later can use also the syntax

<lang fortran>real, dimension(20) :: array</lang>

Dynamic array (in Fortran 90 and later) can be declared as:

<lang fortran>integer, dimension(:), allocatable :: array real, dimension(:,:), allocatable :: multidim_array</lang>

and then the space can be allocated/deallocated with:

<lang fortran>allocate(array(array_dimension)) allocate(multidim_array(20,20)) !... deallocate(array) deallocate(multidim_array)</lang>

where array_dimension is an integer.

Dimension of array can be inspected with size intrinsic, and bounds with ubound and lbound:

<lang fortran> real :: array(20:30), another(10,0:19)

 print *, size(another) ! 10 elements for the first "column", 20 for the second,
                        ! we obtain 200
 print *, size(array)      ! from 20 to 30, we can hold 11 values
 print *, size(another, 1) ! "column" 1 has 10 elements, from 1 to 10
 print *, size(another, 2) ! "column" 2 has 20 elements, from 0 to 19
 print *, lbound(array)    ! lower bound is 20
 print *, ubound(array)    ! upper bound is 30
 print *, lbound(another,1)  ! is 1
 print *, lbound(another,2)  ! is 0
 print *, lbound(another)    ! return an array, (/ 1, 0 /)
 print *, ubound(another,1)  ! is 10
 print *, ubound(another,2)  ! is 19
 print *, ubound(another)    ! return an array, (/ 10, 19 /) </lang>

Outputs

         200
          11
          10
          20
          20
          30
           1
           0
           1           0
          10
          19
          10          19

Haskell

Arrays are initialized either by a list of index-value-pairs or by a list of values:

import Data.Array

a  = array (1,3) [(1,42),(2,87),(3,95)]
a' = listArray (1,3) [42,87,95]

Lower and upper bounds (here 1 and 3) are arbitrary values of any type that is an instance of Ix. If not all initial values are given, the corresponding index is left undefined.

There are several flavours of arrays in Haskell, but creation looks very similar for the others.

IDL

IDL doesn't really distinguish between scalars and arrays - the same operations that can create the one can usually create the other as well.

 a = 3
 help,a
 A               INT       =        3
 print,a^2
      9

 a = [3,5,8,7]
 help,a
 A               INT       = Array[4]
 print,a^2
      9      25      64      49

J

"Creating an array" is topic seldom discussed in J as every verb takes array argument(s) and returns an array result (that is, everything creates an array). For example:

   a=: 3 4 $ 3 1 4 1 5 9 2 6 5 3 5 8  NB. make a 3-by-4 table
   a               NB. display a
3 1 4 1
5 9 2 6
5 3 5 8
   b=: 10 20 30    NB. make a 3-element list
   a + b           NB. add corresponding items of a and b
13 11 14 11
25 29 22 26
35 33 35 38

   ] c=: 3 4 $ 'eleemosynary'  NB. make a 3-by-4 character table and display it
elee
mosy
nary
   |."1 c          NB. reverse each item of c
eele
ysom
yran

Both the a+band the |."1 c expressions create arrays.

Java

For example for an array of 10 int values:

 int[] intArray = new int[10];

Creating an array of Strings:

 String[] s = {"hello" , "World" };

JavaScript

 var myArray = new Array();
 var myArray1 = new Array(5);   // gotcha: preallocated array with five empty elements, not [ 5 ].
 var myArray2 = new Array("Item1","Item2");
 var myArray3 = ["Item1", "Item2"];

Logo

array 5      ; default origin is 1
(array 5 0)  ; custom origin

LSE64

10 myArray :array

MAXScript

Works with: 3D Studio Max version 8

 myArray = #()
 myArray2 = #("Item1", "Item2")

mIRC Scripting Language

Works with: mIRC Script Editor

Works with: mArray Snippet

alias creatmearray { .echo -a $array_create(MyArray, 5, 10) }

Modula-3

Modula-3 arrays include their range in the declaration.

VAR a: ARRAY [1..10] OF INTEGER;

Defines an array of 10 elements, indexed 1 through 10.

Arrays can also be giving initial values:

VAR a := ARRAY [1..10] OF INTEGER {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

Modula-3 also offers "open arrays" just like Oberon-2.

Multi-dimensional arrays can be defined as:

VAR a: ARRAY [1..10], [1..10] OF INTEGER;

Which creates a 2 dimensional array of 10 integers each.

Nial

To create an array of 5 elements with values from 1 to 5

| count 5
1 2 3 4 5

Assign it to a variable

| myarr := count 5

Use an array literal instead

| newarr := [2 4 6]

Oberon-2

Create an array of 10 integers. Initial values are undefined. All arrays are zero-indexed.

VAR a: ARRAY 10 OF INTEGER;

Oberon-2 has no array constructor syntax.

FOR i := 0 TO LEN(a) - 1 DO
  a[i] := i + 1;
END;

Oberon-2 also has dynamically allocated arrays, called "open arrays". It's size is based on how it is initialized.

VAR a: ARRAY OF INTEGER;

Multi-dimensional arrays can be defined as:

VAR a: ARRAY 10, 10, 10 OF INTEGER;

creates a 3 dimensional array of 10 integers each.

OCaml

Using an array literal:

 let array = [| 1; 2; 3; 4; 5 |];;

Converting from a list:

 let array = Array.of_list some_list

To create an array of five elements with the value 0:

 let num_items = 5 and initial_value = 0;;
 let array = Array.make num_items initial_value

To create an array with contents defined by passing each index to a callback (in this example, the array is set to the squares of the numbers 0 through 4):

 let callback index = index * index;;
 let array = Array.init 5 callback

Perl

Works with: Perl version 5

my @empty;
my @empty_too = ();

my @populated   = ('This', 'That', 'And', 'The', 'Other');
print $populated[2];
# And

my $aref = ['This', 'That', 'And', 'The', 'Other'];
print $aref->[2];
# And

# having to quote like that really sucks, and that's why we got syntactic sugar
my @wakey_wakey = qw(coffee sugar cream);

push @wakey_wakey, 'spoon';
# add spoon to right-hand side
my $cutlery = pop @wakey_wakey;
# remove spoon

unshift @wakey_wakey, 'cup';
# add cup to left-hand side
my $container = shift @wakey_wakey;
# remove cup

my @multi_dimensional = (
    [0, 1, 2, 3],
    [qw(a b c d e f g)],
    [qw(! $ % & *)],
];
print $mdref->[1][3];
# d

PHP

For a single dimension array with 10 elements:

 $array = array(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)    //$array[3] == 3
  
 $array = array("a", "b", "c", "d", "e", "f", "g", "h", "i", "j")    //$array[3] == "c"

For a multi-dimension array:

$array = array(
               array(0, 0, 0, 0, 0, 0),
               array(1, 1, 1, 1, 1, 1),
               array(2, 2, 2, 2, 2, 2),
               array(3, 3, 3, 3, 3, 3)
         );
#You would call the array by this code. This will call the 3rd 1 on the second list
echo $array[1][3];

More:

<?php
  $array = array(); /* Blank Array */
  $array[] = "Moo"; /* Sticks Moo in the next index */
  $array2 = array(1 => "A", 2=> "B", 3=>"C", 4=>"Moo"); /* Creates an Array with Values */
  print_r($array); /* Array(0=>"Moo") */
  print_r($array2);
  /*
   Array(
    1 => A
    2 => B
    3 => C
    4 => Moo
  */
  print($array2[5]); // Undefined Index
?>

Pike

For a single dimension int array:

 array(int) x = ({ 1, 2, 3 });

For a single dimension of any type you declare array(mixed) instead of array(int), or just array:

 array x = ({ "a", 1, 5.2 });

For a multi-dimension array, you build an array of arrays:

 mixed x = ({ ({ 5 }),({ 3, 2 }), ({ 1, 8 }) });

Note that inner arrays can be of different sizes, as are simply values of the outer array.

Pop11

Pop11 distinguishes between vectors and arrays. Vectors are one dimensional and the lowest index is 1. There is special shorthand syntax to create vectors:

;;; General creation of vectors, create initialized vector.
lvars v1 = consvector(1, 'a', "b", 3);
;;; Shorthand notation
lvars v2 = {1 'a' b};
;;; Create vector filled with word undef (to signal that elements
;;; are uninitialized)
lvars v3 = initv(3)

Pop11 arrays may have arbitrary lower and upper bounds:

;;; Create array with first index ranging from 2 to 5 and second
;;; index from -1 to 1, initialized with 0
vars a1 = newarray([2 5 -1 1], 0);

Python

List are mutable arrays. You can put anything into a list, including other lists.

<lang python>

empty = []
numbers = [1, 2, 3, 4, 5]
zeros = [0] * 10
anything = [1, 'foo', 2.57, None, zeros]
digits = range(10)  # 0, 1 ... 9
evens  = range(0,10,2)  # 0, 2, 4 ... 8
evens = [x for x in range(10) if not x % 2]  # same using list comprehension
words = 'perl style'.split()

</lang>

Tuples are immutable arrays. Note that tuples are defined by the "," - the parenthesis are optional (except to disambiguate when creating an empty or single-element tuple):

<lang python>

empty = ()
numbers = (1, 2, 3, 4, 5)
numbers2 = 1,2,3,4,5           # same as previous
zeros = (0,) * 10
anything = (1, 'foo', 2.57, None, zeros)

</lang>

Both lists and tuples can be created from other iterateables:

<lang python> >>> list('abc') ['a', 'b', 'c'] >>> tuple('abc') ('a', 'b', 'c') >>> list({'a': 1, 'b': 2, 'c': 3}) ['a', 'c', 'b'] >>> open('file', 'w').write('1\n2\n3\n') >>> list(open('file')) ['1\n', '2\n', '3\n'] </lang>

Note: In Python 2.6 the collections.namedtuple factory was added to the standard libraries. This can be used to create classes of lightweight objects (c.f. the Flyweight design pattern) which are tuples that can additionally support named fields.

Raven

[ 1 2 3.14 'a' 'b' 'c' ] as a_list
a_list print

list (6 items)
 0 => 1
 1 => 2
 2 => 3.14
 3 => "a"
 4 => "b"
 5 => "c"

Ruby

my_array = Array.new
# This is the most basic way to create an empty one-dimensional array in Ruby.

my_array = 1, 2, 3, 4, 5
# Ruby treats comma separated values on the right hand side of assignment as array. You could optionally surround the list with square bracks
# my_array = [ 1, 2, 3, 4, 5 ]

array = [
  [0, 0, 0, 0, 0, 0],
  [1, 1, 1, 1, 1, 1],
  [2, 2, 2, 2, 2, 2],
  [3, 3, 3, 3, 3, 3]
]

# You would call the array by this code. This will call the 4th 1 on the second list
array[1][3]

# You can also create a sequential array from a range using the 'splat' operator:
array = [*0..3]
# or use the .to_a method for Ranges
array = (0..3).to_a

#=> [0,1,2,3]

# This lets us create the above programmatically:
array = [*0..3].map {|i| [i] * 6}
# or use the .map (.collect which is the same) method for Ranges directly
# note also that arrays of length 6 with a default element are created using Array.new
array = (0..3).map {|i| Array.new(6,i)}
# you can also do the first map using Array.new too
array = Array.new(4) {|i| Array.new(6,i)}

#=> [[0, 0, 0, 0, 0, 0], [1, 1, 1, 1, 1, 1], [2, 2, 2, 2, 2, 2], [3, 3, 3, 3, 3, 3]]

Scala

 val array = new Array[int](10) // a 10 element array
 val stringArray = new Array[String](20) // a 20 element string array
 List("Elwood", "Madeline", "Archer").toArray
 (List(1,2,3) ::: List(4,5,6)).toArray
 (1 :: 2 :: 3 :: 4 :: 5 :: Nil).toArray

Scheme

Lists are more often used in Scheme than vectors.

Using an array literal:

 #(1 2 3 4 5)

To create an array of five elements:

 (make-vector 5)

To create an array of five elements with the value 0:

 (make-vector 5 0)

Script3D

Script3D has dynamic arrays allowing to store any datatype and a special type for storing vectors of floating point values, typically used in 3D applications.

  var myArray = { "a string" , 1, true, "mixed", Void, 1.5}; // array from list
  var myArray = Array(10);  // 10 elements array

  var myVector = [1,2,3,4];
  var myVector = Vector(2000); // 2000 elements vector of floats

Smalltalk

<lang smalltalk>|array| "creates an array that holds up to 20 elements" array := Array new: 20 . "access the first element: array base is 1" (array at: 1) displayNl. "put 100 as second value; you can put any object,

in particular SmallInteger"

array at: 2 put: 100.</lang>

Standard ML

Converting from a list:

 val array = Array.fromList [1,2,3,4,5]

To create an array of five elements with the value 0:

 val num_items = 5 and initial_value = 0;
 val array = Array.array (num_items, initial_value)

To create an array with contents defined by passing each index to a callback (in this example, the array is set to the squares of the numbers 0 through 4):

 fun callback index = index * index;
 val array = Array.tabulate (5, callback)

In addition to arrays, the Standard ML library also has "vectors", which are immutable arrays. Most implementations support the following syntax for a vector literal, although it is not standard:

 val vector = #[1,2,3,4,5]

Tcl

Tcl uses the list for what many other languages call "array". A list is an ordered, numerically indexable collection of values in a single variable. Each list entry itself can be a list.

 set a [list 5 hello {} [expr 3*5]]

this creates a list with the name a and four elements - the number 5, the word "hello", an empty list, and the result of the expression "3*5".

Tcl does have an "array", though, which is really an "associative array":

 array set b {foo 12 bar hello}

this creates an array with the name b with two elements. The keys of the elements are "foo" and "bar" and the values are b(foo) == 12 and b(bar) == hello.

Toka

Toka allows creation of an array using is-array. Access to the elements is done using get-element, put-element, get-char-element, and put-char-element functions. You can not initialize the values automatically using the core array functions.

 100 cells is-array foo
 100 chars is-array bar

Visual Basic .NET

Implicit Size

' An empty array of integers.
Dim empty() AS Integer = {}
' An array of integers.
Dim numbers() AS Integer = {1, 2, 3, 4, 5}
' An array of strings
Dim string() AS String = {"String","foo","etc."}

Explicit Size

' An empty array of integers.
Dim empty(0) AS Integer = {}
' An array of integers.
Dim numbers(4) AS Integer = {1, 2, 3, 4, 5}
' An array of strings
Dim String(2) AS String = {"String","foo","etc."}

Resize An Array

' An empty array of integers.
Dim empty() As Integer = {}
Private Sub ReDimension()
    ' Resize (And keep all elements intact)
    ReDim Preserve empty(1)
    ' Resize (Erase all elements)
    ReDim empty(1)
End Sub

Splitting strings into arrays

Dim words() AS String = 'perl style'.split(" "c) ' You must tell VB that the space is a character by denoting c after the " "

VBScript

Dim myArray(2)
myArray(0) = "Hello"
myArray(1) = "World"
myArray(2) = "!"