Retrieving an Element of an Array

From Rosetta Code

alprazolam online viagra online albuterol online free sagem ringtones buy zanaflex propecia online cheap soma order paxil sildenafil online cyclobenzaprine online meridia online free funny ringtones cheap valium cheap fioricet cheap nexium nexium online cheap zanaflex free funny ringtones free samsung ringtones but ultracet cheap lorazepam wellbutrin online but adipex hgh online cheap vigrx cheap diazepam but lortab buy alprazolam tracfone ringtones free real ringtones meridia free verizon ringtones midi ringtones free sonyericsson ringtones cheap wellbutrin paxil online cialis hoodia online cheap valium buy tramadol mp3 ringtones free jazz ringtones buy ultram alprazolam online mp3 ringtones free sprint ringtones ultracet online midi ringtones mono ringtones online flexeril funny ringtones free mono ringtones pharmacy online online lorazepam online cheap vigrx nokia ringtones cheap prozac xanax online phentermine tracfone ringtones buy tramadol free qwest ringtones clonazepam online cheap vicodin cheap viagra free sagem ringtones prozac online music ringtones mp3 ringtones ativan online cheap clonazepam cheap lortab free nokia ringtones free nextel ringtones cheap valium cheap ultracet cheap clomid free kyocera ringtones cheap alprazolam free qwest ringtones cheap soma lortab online valium online buy wellbutrin cingular ringtones midi ringtones free jazz ringtones free real ringtones free sharp ringtones tenuate cheap hydrocodone tracfone ringtones free motorola ringtones lisinopril online online zanaflex cheap ortho hoodia online sony ericsson ringtones free free ringtones clonazepam online rivotril online free tracfone ringtones [http://users.wpi.edu/~dance/blahdocs/uploads/fioricet_2815.htm users.wpi.edu/~dance/blahdocs/uploads/

] free mono ringtones cheap levitra tracfone ringtones cheap tenuate order phentermine diethylpropion online ericsson ringtones ambien online ortho online ericsson ringtones celexa online free free ringtones tramadol online meridia online cheap xenical cheap zoloft cheap hydrocodone cyclobenzaprine online free nokia ringtones buy adipex verizon ringtones phentermine online mono ringtones mono ringtones cheap celexa lipitor online free alltel ringtones free alltel ringtones cheap clonazepam xanax online zyban online punk ringtones cheap wellbutrin levitra online lisinopril online norco online free samsung ringtones vicodin ultracet online norco lipitor online buy lortab tenuate online nextel ringtones lorazepam online free music ringtones but ortho cheap xenical diazepam online buy adipex free samsung ringtones carisoprodol online cheap albuterol free alltel ringtones buy paxil buy rivotril levitra online wellbutrin online levitra online free ringtones buy pharmacy online carisoprodol online tramadol online cyclobenzaprine online mono ringtones cheap ativan sony ericsson ringtones but phentermine free mp3 ringtones sony ericsson ringtones soma online viagra online ultram cheap didrex order norco sagem ringtones sprint ringtones online cialis sprint ringtones sprint ringtones polyphonic ringtones nexium online cheap hydrocodone cheap tramadol mtv ringtones sony ericsson ringtones wwe ringtones free nextel ringtones funny ringtones free mtv ringtones ultracet online rivotril online lisinopril online xanax online wwe ringtones sildenafil online cheap ambien

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

In this task, the goal is to retrieve an element of an array.

4D

  ` first element
$elem:=$array{1}

X86 assembly

Assembler: nasm

mov esi, array_offset
mov ebx, 2
mov eax, [esi ebx*4]

ActionScript

var arr:Array = new Array(1,2,3);
var myVar:Number = arr[1];
// the value of myVar is: 2

Ada

Array indexed by an enumerated type. Ada enumerated types are discrete non-numeric types.

type Days is (Mon, Tue, Wed, Thu, Fri, Sat, Sun);
type Daily_Counts is array(Days) of Natural;
This_week : Daily_Counts := (200, 212, 175 220, 201, 120, 0);
Monday_Sales : Natural;
Monday_Sales := This_Week(Mon); 

Monday_Sales is assigned 200

AppleScript

on getArrayValue(array, location)
    -- very important -- The list index starts at 1 not 0
    return item location in array
end getArrayValue

C

 int array_index(int array[], int index) {
   return array[index];
 }

C#

 int getArrayValue( int values[], int index ) {
   return values[index];
 }
 

C

 template<typename T>
 T array_index(T array[], size_t index) {
   return array[index];
 }

ColdFusion

<cfset arr = ArrayNew(1)>
<cfset arr[1] = "one">
<cfset arr[2] = "2">
<cfset arr[3] = 3>
<cfset var = arr[1]>

The value of var is "one"

ColdFusion Arrays are NOT zero-based, their index begins at 1

Common Lisp

  (defun array-value (array index)
    (aref array index))

Delphi/Object Pascal/Turbo Pascal/Standard Pascal

Array's in all the flavors of pascal can be of any valid base type, or user defined type ( which are all made up of base types ) and are multi-dimensional. With Delphi dynamic arrays were defined but had been used in pascal since its inseption.

A Static array defintion:

foo : array[1..10] of integer; { The base index is ONE }

The base index can be freely chosen:

foo: array[7 .. 16] of integer; { The base index is 7 }

Indeed, the "1 .. 10" resp. "7 .. 16" are actually types: they are integer subrange types. Arrays can also be indexed by enumeration types or enumeration subrange types:

type
 rainbowcolor = (red, orange, yellow, green, blue, violet);
var
 foo: array[rainbowcolor] of integer;
 bar: array[yellow .. blue] of integer;
 i: integer
begin
 i := foo[red]; { allowed indices are red, orange, yellow, green, blue, violet }
 i := bar[green]; { allowed indices are yellow, green, blue }
end;

A Dynamic Array type in Delphi:

foo : array of integer ; // The base index is ZERO

An "old school" dynamic array in the various flavors of pascal

foo : array[0..0] of integer;  // The base index is ZERO

A dynamic array in Extended Pascal:

type
 intarray(n: integer) = array[1 .. n] of integer; { base index 1 }
var
 foo: ^intarray;
begin
 new(foo, 10); { foo now has index 1 to 10 }
 i := foo[2];
 dispose(foo); { get rid of the array }
end;

In the case of the static array, the compiler generates the code to allocate the required memory to hold 10 integers.

In the Delphi style ---dynamic--- array you must set its length:

SetLength(foo,10);  // this array will no hold 10 integers

In the "old school" style of dynamic arrays, you created a point to the zero length declaration and then allocated memory to it with GetMem

pFoo : ^Foo ;
Foo  : array[0..0] of integer ;

All arrays are accessed the same way regardless of declaration method.

i : integer ;

i := foo[n] ;

where n is the array index who's base is either 1 or 0 depending on how it was declared.

Erlang

Erlang lists are 1-based which means that the index must be within the bounds (1 .. length(List)):

Value = lists:nth(Index, List).

Forth

Forth does not have special syntax for array access. Address arithmetic is used to access contiguous memory.

create array 1 , 2 , 3 , 4 ,
array 2 cells   @ .    \ 3

IDL

 ; this is allowed:
 result = arr(5) 
 ; but this is preferred:
 result = arr[5]

The form with square brackets is preferred as it unambiguously constitutes array access, while the version with round ones can conflict with a function call if there are both a function and an array with the same name arr.

Java

public Object getArrayElem(Object[] array, int pos) {
    return array[pos];
}

JavaScript

var element = array[index];

mIRC

Interpeter: mIRC Script Editor

Library: mArray Snippet

 alias readmyarray { echo -a $array_read(MyArray, 2, 3) }

Perl

Interpreter: Perl 5.8.8

$elem = $array[0];

PHP

$array = array('php', 'has', 'arrays');
// First element 
$elem  = $array[0];

Pop11

lvars ar = {1 two 'three'};
lvars elem;
;;; Access second element and assign to variable elem
ar(2) -> elem;

This example uses the simplest possible array (a vector). Pop11 has more general arrays, but in all cases access follows the same pattern, and look the same as procedure (function) call.

Python

Interpreter: Python 2.5

The item is an element in a list at a given index

 item = aList[index]

or

To use a list like a stack be it FIFO/LIFO

 aList.pop()  # Pop last item in a list
 aList.pop(0) # Pop first item in a list

Note: When using the pop() method, the element is removed from the list.

Ruby

 ary = ['Ruby','rules','big','time']
 #the first element
 element = ary[0]
 #or
 element = ary.first
 # => element = 'Ruby'
 #the last element
 element = ary[-1]
 #or
 element = ary.last
 # => element = 'time'
 #retrieving different values at once
 elements = ary.values_at(0,2,3)
 # => elements = ['Ruby','big','time']
 #select the first element of length 3
 element = ary.find{|el|el.length==3}
 # => element = "big"

Smalltalk

  "Retrieve second element of an array"
  index := 2
  element := anArray at: index

Tcl

All arrays in Tcl are associative. If "key" is the variable that holds the key of the element to be retrieved, then

 set result $array($key)

Toka

This retrieves the value 20 from the second item in the array:

 3 cells is-array table
 ( Populate the array )
 10 0 table put-element
 20 1 table put-element 
 30 2 table put-element
 
 table 1 get-element