How to insert an item at the beginning of an array in PHP?

Question

I know how to insert it to the end by:

$arr[] = $item;

But how to insert it to the beginning?

`$arr[-1] = $item;` Found here: http://stackoverflow.com/a/15252657/669677 — , Jul 04 '13 at 14:22
@2astalavista, that doesn't work: `print_r($arr)` => `Array ( [0] => a, [1] => b, [-1] => c )` — laurent, Jan 28 '14 at 07:07
@returnthis.lau_ this case you should use for loop - starting from -1 - to make it work: `for ($i = -1; $i < count($a)-1; $i++)` as the referenced link showed, but it is easy to forget, so I don't prefer that solution any more. — , Jan 28 '14 at 09:13

score 464 · Accepted Answer · edited Sep 16 '13 at 15:01

464

Use array_unshift($array, $item);

$arr = array('item2', 'item3', 'item4');
array_unshift($arr , 'item1');
print_r($arr);

will give you

Array
(
 [0] => item1
 [1] => item2
 [2] => item3
 [3] => item4
)

edited Sep 16 '13 at 15:01

Toby Allen

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answered Nov 16 '09 at 02:19

Trav L

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7

What about if you need literal, rather than numeric, keys? – Evan Dec 06 '13 at 04:52
4

@Evan, the documentation for `array_unshift` says the following `All numerical array keys will be modified to start counting from zero while literal keys won't be touched.` – craned Dec 04 '15 at 23:23
1

There are two problem: 1)reindexing the array 2)can not add item with an index. – Nabi K.A.Z. Jun 13 '19 at 21:23
2

If you have an associative array or need to preserve keys then see the user examples here: https://www.php.net/manual/en/function.array-unshift.php there are a couple good examples of how to accomplish this! – Vallier Aug 22 '19 at 21:59

score 152 · Answer 2 · answered May 13 '13 at 10:48

152

In case of an associative array or numbered array where you do not want to change the array keys:

$firstItem = array('foo' => 'bar');

$arr = $firstItem + $arr;

array_merge does not work as it always reindexes the array.

answered May 13 '13 at 10:48

tihe

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Attention! "The + operator returns the right-hand array appended to the left-hand array; for keys that exist in both arrays, the elements from the left-hand array will be used, and the matching elements from the right-hand array will be ignored." -- See: https://stackoverflow.com/a/2140094/3411766 – cottton Apr 12 '18 at 12:42
The solution it's good because can add item with an index, and didn't reindexing the array; But have just a note about remove item in the right hand array, if there are same index in the left hand array. – Nabi K.A.Z. Jun 13 '19 at 21:27

nito · Answer 3 · 2022-09-14T16:34:56.647

Since PHP7.4 you can use the spread opperator, very similar to JavaScript

$arr = [$item, ...$arr];

https://wiki.php.net/rfc/spread_operator_for_array

A few more examples:

// Add an item before
$arr = [$item, ...$arr];

// Add an item after
$arr = [...$arr, $item];

// Add a few more
$arr = [$item1, $item2, ...$arr, $item3];

// Multiple arrays and and items
$arr = [$item1, ...$arr1, $item2, ...$arr2, $item3];

Note: this is only possible with int keys, not for associative arrays.
Note2: The keys are not kept.

BREAKING Example:

$car = ['brand' => 'Audi', 'model' => 'A8'];
$engine = ['cylinder' => 6, 'displacement' => '3000cc'];

$merged = [...$car, ...$engine];

var_dump($merged);

Will result in:

[ Error ] Cannot unpack array with string keys

What's the difference between your example 'item before' and 'item after' — crafter, Sep 13 '22 at 07:15

Manish Dhruw · Answer 4 · 2020-11-21T09:05:33.157

14

Insert an item in the beginning of an associative array with string/custom key

<?php

$array = ['keyOne'=>'valueOne', 'keyTwo'=>'valueTwo'];

$array = array_reverse($array);

$array['newKey'] = 'newValue';

$array = array_reverse($array);

RESULT

[
  'newKey' => 'newValue',
  'keyOne' => 'valueOne',
  'keyTwo' => 'valueTwo'
]

edited Nov 21 '20 at 09:05

answered Apr 06 '18 at 08:50

Manish Dhruw

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clever, but a bit expensive for large arrays – Rohit Gupta Apr 09 '22 at 04:58

score 14 · Answer 5 · answered May 14 '20 at 16:32

14

For an associative array you can just use merge.

$arr = array('item2', 'item3', 'item4');
$arr = array_merge(array('item1'), $arr)

answered May 14 '20 at 16:32

pictoru

722
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array_merge resets array keys. so this is not good solution. Thanks. – Kamlesh May 21 '21 at 08:21

score 8 · Answer 6 · edited Apr 09 '22 at 05:02

8

Use array_unshift() to insert the first element in an array.

Use array_shift() to remove the first element of an array.

edited Apr 09 '22 at 05:02

Rohit Gupta

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answered May 13 '13 at 11:16

Vinit Kadkol

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Answers are better with examples – Rohit Gupta Apr 09 '22 at 05:02
ok will add it.. thanks for highlighting – Vinit Kadkol Aug 16 '22 at 08:31

score 7 · Answer 7 · answered Jul 21 '21 at 09:05

There are two solutions:

if you have array with keys that matter to you

$new = ['RLG' => array(1,2,3)];
$array = ['s' => array(2,3), 'l' => [], 'o' => [], 'e' => []];

$arrayWithNewAddedItem = array_merge($new, $array);

if you have an array without any keys.

array_unshift(array, value1);

score 4 · Answer 8 · answered Mar 03 '15 at 18:25

Or you can use temporary array and then delete the real one if you want to change it while in cycle:

$array = array(0 => 'a', 1 => 'b', 2 => 'c');
$temp_array = $array[1];

unset($array[1]);
array_unshift($array , $temp_array);

the output will be:

array(0 => 'b', 1 => 'a', 2 => 'c')

and when are doing it while in cycle, you should clean $temp_array after appending item to array.

How to insert an item at the beginning of an array in PHP?

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