array_fill

(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)

array_fillFill an array with values

Description

array_fill(int $start_index, int $count, mixed $value): array

Fills an array with count entries of the value of the value parameter, keys starting at the start_index parameter.

Parameters

start_index

The first index of the returned array.

If start_index is negative, the first index of the returned array will be start_index and the following indices will start from zero prior to PHP 8.0.0; as of PHP 8.0.0, negative keys are incremented normally (see example).

count

Number of elements to insert. Must be greater than or equal to zero, and less than or equal to 2147483647.

value

Value to use for filling

Return Values

Returns the filled array

Errors/Exceptions

Throws a ValueError if count is out of range.

Changelog

Version Description
8.0.0 array_fill() now throws a ValueError if count is out of range; previously E_WARNING was raised, and the function returned false.

Examples

Example #1 array_fill() example

<?php
$a
= array_fill(5, 6, 'banana');
print_r($a);
?>

The above example will output:

Array
(
    [5]  => banana
    [6]  => banana
    [7]  => banana
    [8]  => banana
    [9]  => banana
    [10] => banana
)

Example #2 array_fill() example with a negative start index

<?php
$a
= array_fill(-2, 4, 'pear');
print_r($a);
?>

Output of the above example in PHP 7:

Array
(
    [-2] => pear
    [0] => pear
    [1] => pear
    [2] => pear
)

Output of the above example in PHP 8:

Array
(
    [-2] => pear
    [-1] => pear
    [0] => pear
    [1] => pear
)

Note that index -1 is not present prior to PHP 8.0.0.

Notes

See also the Arrays section of manual for a detailed explanation of negative keys.

See Also

add a note

User Contributed Notes 7 notes

up
81
csst0266 at cs dot uoi dot gr
19 years ago
This is what I recently did to quickly create a two dimensional array (10x10), initialized to 0:

<?php
$a
= array_fill(0, 10, array_fill(0, 10, 0));
?>

This should work for as many dimensions as you want, each time passing to array_fill() (as the 3rd argument) another array_fill() function.
up
45
anatoliy at ukhvanovy dot name
10 years ago
If you need negative indices:
<?php
$b
= array_fill(-2, 4, 'pear');//this is not what we want
$c = array_fill_keys(range(-2,1),'pear');//these are negative indices
print_r($b);
print_r($c);
?>
Here is result of the code above:
Array
(
[-2] => pear
[0] => pear
[1] => pear
[2] => pear
)
Array
(
[-2] => pear
[-1] => pear
[0] => pear
[1] => pear
)
up
3
user at NOSPAM dot example dot com
3 years ago
As of PHP 8.0 the example code

<?php
$b
= array_fill(-2, 4, 'pear');
print_r($b);
?>

now returns

Array
(
[-2] => pear
[-1] => pear
[0] => pear
[1] => pear
)

See https://wiki.php.net/rfc/negative_array_index and https://github.com/php/php-src/pull/3772
up
35
mchljnk at NOSPAM dot gmail dot com
10 years ago
Using objects with array_fill may cause unexpected results. Consider the following:

<?php
class Foo {
public
$bar = "banana";
}

//fill an array with objects
$array = array_fill(0, 2, new Foo());

var_dump($array);
/*
array(2) {
[0]=>
object(Foo)#1 (1) {
["bar"]=>
string(6) "banana"
}
[1]=>
object(Foo)#1 (1) {
["bar"]=>
string(6) "banana"
}
} */

//now we change the attribute of the object stored in index 0
//this actually changes the attribute for EACH object in the ENTIRE array
$array[0]->bar = "apple";

var_dump($array);
/*
array(2) {
[0]=>
object(Foo)#1 (1) {
["bar"]=>
string(5) "apple"
}
[1]=>
object(Foo)#1 (1) {
["bar"]=>
string(5) "apple"
}
}
*/
?>

Objects are filled in the array BY REFERENCE. They are not copied for each element in the array.
up
1
miguelxpain at gmail dot com
12 years ago
I made this function named "array_getMax" that returns te maximum value and index, from array:

<?php
//using array_search_all by helenadeus at gmail dot com

function array_search_all($needle, $haystack)
{
#array_search_match($needle, $haystack) returns all the keys of the values that match $needle in $haystack

foreach ($haystack as $k=>$v) {

if(
$haystack[$k]==$needle){

$array[] = $k;
}
}
return (
$array);


}

function
array_getMax($array){

$conteo=array_count_values($array);

if(
count($conteo)==1 ){//returns full array when all values are the same.
return $array;
}

arsort($array);

//$antValue=null;
$maxValue=null;
$keyValue=null;
foreach(
$array as $key=>$value){
if(
$maxValue==null){
$maxValue=$value;
$keyValue=$key;
break;
}
}

$resultSearch=array_search_all($maxValue, $array);

return
array_fill_keys($resultSearch, $maxValue);


}

//example
$arreglo=array('e1'=>99,'e2'=>'99','e3'=>1,'e4'=>1,'e5'=>98);

var_dump(array_getMax($arreglo));

//output
/*
array(2) {
["e1"]=>
int(99)
["e2"]=>
int(99)
}
*/
?>

I hope some one find this usefull
up
-2
Hayley Watson
6 years ago
Fill missing keys in a (numerically-indexed) array with a default value

<?php

function fill_missing_keys($array, $default = null, $atleast = 0)
{
return
$array + array_fill(0, max($atleast, max(array_keys($array))), $default);
}

?>
up
-28
Anonymous
21 years ago
array_fill() cannot be used to setup only missing keys in an array. This may be necessary for example before using implode() on a sparse filled array.
The solution is to use this function:

<?php
function array_setkeys(&$array, $fill = NULL) {
$indexmax = -1;
for (
end($array); $key = key($array); prev($array)) {
if (
$key > $indexmax)
$indexmax = $key;
}
for (
$i = 0; $i <= $indexmax; $i++) {
if (!isset(
$array[$i]))
$array[$i] = $fill;
}
ksort($array);
}
?>

This is usefull in some situations where you don't know which key index was filled and you want to preserve the association between a positioned field in an imploded array and the key index when exploding it.
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