Assigning Values to an Array: Difference between revisions

{{task|Basic language learning}}

{{Template:clarify task}}

In this task, the goal is to assign a value to an element of an [[array]]. The value should only replace an existing value, and not insert a new key should the key not exist. If the key does not exist, an error should be returned.

arr[0] = 1;

arr[1] = 'a';

arr[2] = 5.678;

{{works with|GCC| 4.1.2}}

<lang ada>package Pkg is

end Pkg;</lang>

Declarations:

FLEX [1:8] INT array:=(1,2,3,4,5,6,7,8);

+333 +2 +33 +44 +55 +6 +7 +8 +333

array[index]←value

APL is array-oriented, and so there are many different and powerful ways to index and assign arrays. Asking an APLer how one assigns a value to an array index is like asking an Eskimo how one says "snow". The above is just tip of the iceberg (i.e. a direct translation of the non-array-oriented code examples on this page).

set item location of array to value

set end of array to item

In the first example, a["hello"] is overwritten; in the second, a["hellx"] is not added.

<lang awk>

awk: cmd. line:1: fatal: division by zero attempted</lang>

To assign values 5, 6, and 7 to array elements 1,2,3:

>+++++++ move value 7 to element 3

<lang c> #include <sys/types.h>

int writeToIntArray(int *array, size_t array_sz, int loc, int val)

}</lang>

'''Language Version:''' 1.0+

<lang csharp>

</lang>

{{works with|g++| 4.1.2}}

template<class T, std::size:t size>

}

<cffunction name="writeToArray">

<cfargument name="array">

<cfset myArray[3] = 987654>

(setf (aref array index) value)

void setValue(T) (T[] array, size_t index, T newValue) { array[index] = newValue; }

In E, you may expect that the FlexList data type is an array or something similarly efficient. However, a FlexList will implicitly extend itself if you give an index equal to the current size. Therefore, to implement the specified task:

The basic assignment operation, <code>a[b] := c</code>, is syntactic sugar; it is equivalent to <code>a.put(b, c)</code>, except that it returns <var>c</var> rather than the result of the call.

procedure WriteToIntArray(var Arr: array of Integer; Loc: Integer; Val: Integer);

begin

end;

'''Interpreter:''' ANS Forth

: ]! ( n addr ix -- ) cells + ! ; \ ex. 3 buffer[ 2 ]!

In ISO Fortran 90 or later, use an array initializer (with RESHAPE intrinsic for multidimensional arrays):

real, dimension(50) :: a = (/ (1.0/(i*i),i=1,50) /)

a(55) = 12

let arr = [| 0; 1; 2; 3 |]

arr.[0] <- 100

Array.set arr 1 101 // alternative method

Groovy, like every other C-derived language in the known universe, uses ZERO-based array/list indexing.

</pre>

{{works with|GHC| 6.6}}

===List===

</pre>

array =: 5 5 5 5 5 5 5

5 5 88 99 88 5 5

{{works with|J2SE| 1.2+}}

<lang java>public void writeToIntArray(int[] array, int loc, int val){

}</lang>

function setElem(array, loc, val) { //returns 0 if out of bounds

if(typeof array[loc] == typeof undefined) {

function writeToArray(array, loc, val) { array[loc] = val; }

make "a {10 20 30}

setitem 1 :a "ten

10 array :array

0 array 5 [] ! # store 0 at the sixth cell in the array

{{works with|mIRC|}}

{{works with|mArray Snippet|}}

alias write2array { echo -a $array_write(MyArray, 2, 3, Rosetta) }

Just like Part can extract parts of expressions, it can also be used to assign an element to a value:

<lang Mathematica>

</lang>

<pre>arr[index] = value</pre>

MAXScript arrays dynamically resize when assigning to an index that previously didn't exist.

a := 1 2 3 4

a@1 := 100

=1 100 3 4

{{works with|GCC| 3.3+}}

}

{{works with|OCaml|}}

arr.(loc) <- val;

Array.set arr loc val;

{{works with|Perl|5.8.8}}

# will replace the 4th, 5th and 6th elements with the first 3 values in @values

<?php

?>

'''Interpreter:''' Oracle compiler

set serveroutput on

/

value -> array(index);

To change existing item, (raise IndexError if the index does not exists):

<lang R>

#Create array

</lang>

{{works with|Ruby| 1.8.5}}

# To specify a value for a known index

arr << 1

val array = new Array[int](10) // create a 10 element array of integers

array(3) = 44

l(2) // 2

(vector-set! arr loc val)

<lang slate>

</lang>

<lang smalltalk>"suppose array is bound to an array of 20 values"

do: [ :sig | 'Out of range!' displayNl ].</lang>

Array.update (arr, loc, val);

<lang tcl>proc setIfExist {theVariable value} {

upvar 1 $theVariable variable

setIfExist x 10 ;# error if x doesn't exist</lang>

100 cells is-array foo

1000 10 foo array.put ( Put value '1000' into array 'foo' at slot '10' )

char: A 1 foo array.putChar ( Put value 'A' (ASCII code) into character array 'bar' at slot '1' )

'''Language Version:''' 5.0+

Private Function writeToArray(intArray() As Integer, arraySize As Integer, loc As Integer, value As Integer) As Integer

End Function

===Simple Example===