Creating an Array

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

//  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);

Ada

Compiler: GCC 4.1.2

Ada array indices may begin at any value, not just 0 or 1

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);

Ada arrays may be indexed by enumerated types, which are discrete non-numeric types

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);

AppleScript

AppleScript supports "arrays" as "lists," and they are not limited by a single type.

set array1 to {}
set array2 to {1, 2, 3, 4, "hello", "world"}

BASIC

Interpeter: QuickBasic 4.5, PB 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

Compiler: GCC, MSVC, BCC, Watcom

Libraries: Standard 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++

Compiler: GCC, Visual C++, BCC, Watcom

Using dynamically-allocated 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 memory:

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

Libraries: STL

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

Libraries: Qt

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

Libraries: Microsoft Foundation Classes

 // 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-Deminsional 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.

(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 'fixnum :initial-contents '(1 2 3 4) :adjustable t)

D

Compiler: DMD,GDC

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

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

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 to MyArray

Dynamic array free:

MyArray free
0 to MyArray

Fortran

Default case:

      integer a(10)

this will have ten elements. Counting starts at 1. If a zero-based array is needed, declare like this:

      integer a(0:9)

this mechanism can be extended to any numerical indices, and allowed number of dimensions (and of course to other data types than integers). For example

      real*8 (25:29,12)

will be an two-dimensional, 5x12-array of 8-byte floats, where the first dimension can be addressed numerically as 25, 26, 27, 28 or 29 (and the second dimension as 1 .. 12).

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

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 myArray2 = new Array("Item1","Item2");
 var myArray3 = ["Item1", "Item2"];

MAXScript

Interpreter: 3D Studio Max 8

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

mIRC Scripting Language

Interpeter: mIRC Script Editor Libraries: mArray Snippet

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

OCaml

Using an array literal:

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

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

Interpeter: Perl

use vars qw{ @Array };

@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 3rd 1 on the second list
print $Array[1][3];

 # Alternative:
 my @array_using_qw = qw/coffee sugar cream/;

 # Alternative:
 my @Array3 = ();
 push @Array3,   "Item1";
 push @Array3,   "Item2";
 $Array3[2]    = "Item3";
 $Array3[3][0] = "Item4";

 @Array = ('This', 'That', 'And', 'The', 'Other');

 $ArrayRef = ['This', 'That', 'And', 'The', 'Other'];
 print $ArrayRef->[2]; # would print "And"

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];

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.
vars v1 = consvector(1, 'a', "b", 3);
;;; Shorthand notation
vars v2 = {1 'a' b};
;;; Create vector filled with word undef (to signal that elements
;;; are uninitialized
vars 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

Interpeter: Python 2.3, 2.4, 2.5

A Python list() is implemented as a dynamical array.

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 3rd 1 on the second list:

 array[1][3]

Alternatively you can create it programmatically with a list comprehension:

array = [[i]*6 for i in xrange(4)]

Create an empty array:

array = []

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)}

#=> [[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

Smalltalk

  array := Array withAll: #('an' 'apple' 'a' 'day' 'keeps' 'the' 'doctor' 'away').

  "Access the first element of the array"
  elem := array at: 1.

  "Replace apple with orange"
  array at: 2 put: 'orange'.

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.

Visual Basic .NET

Compiler: Visual Basic .NET 2005

Dim myArray() as String = New String() {"Hello", "World", "!"}

VBScript

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