Insert new item in array on any position in PHP

Question

How can I insert a new item into an array on any position, for example in the middle of array?

Possible duplicate of [How to insert element into arrays at specific position?](https://stackoverflow.com/questions/3353745/how-to-insert-element-into-arrays-at-specific-position) — Kashyap Kotak, Jun 22 '18 at 15:08

score 1029 · Accepted Answer · edited Jul 17 '18 at 16:07

1029

You may find this a little more intuitive. It only requires one function call to array_splice:

$original = array( 'a', 'b', 'c', 'd', 'e' );
$inserted = array( 'x' ); // not necessarily an array, see manual quote

array_splice( $original, 3, 0, $inserted ); // splice in at position 3
// $original is now a b c x d e

If replacement is just one element it is not necessary to put array() around it, unless the element is an array itself, an object or NULL.

edited Jul 17 '18 at 16:07

Félix Gagnon-Grenier

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answered Sep 26 '10 at 11:14

jay.lee

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43

It's odd that such a basic functionality is actually sort of hidden, in that the main purpose of this function as described in the documentation is something different (replace stuff in arrays). Yes, it is pointed out in the arguments section, but if you are just scanning function descriptions to find what to use to insert in arrays you would have never found it. – Mahn Jun 21 '12 at 00:26
30

Just saying that this will not preserve keys in the `$inserted` array. – mauris Jun 27 '12 at 06:58
6

Also in PHP manual, example #1: http://php.net/manual/en/function.array-splice.php – marcovtwout Dec 03 '12 at 13:16
3

@JacerOmri it is totally right, both statements are valid. You can pass a value of any type, but it might not behave the same for an array, an object, or null. For scalars, type-casting `(array)$scalar` is equivalent to `array($scalar)`, but for an array, an object, or null, it will be ignored (array), convert to an array (object), or become an empty array (null) - see http://php.net/manual/en/language.types.array.php#language.types.array.casting – Lukas Nov 27 '14 at 07:49
3

@SunilPachlangia, adelval and others: with multi-dimensional arrays you need to wrap the replacement in an array, it's documented. I still brought the note here so people stop doing the mistake. – Félix Gagnon-Grenier Jul 17 '18 at 16:09
2

@SunilPachlangia For a multidimensional array, this function allowed me to insert an array at a specified position: https://gist.github.com/wpscholar/0deadce1bbfa4adb4e4c It seems similar to other functions on this page, but I found it easier to understand. – Ryan May 07 '19 at 22:15

Halil Özgür · Answer 2 · 2015-10-20T17:40:05.183

A function that can insert at both integer and string positions:

/**
 * @param array      $array
 * @param int|string $position
 * @param mixed      $insert
 */
function array_insert(&$array, $position, $insert)
{
    if (is_int($position)) {
        array_splice($array, $position, 0, $insert);
    } else {
        $pos   = array_search($position, array_keys($array));
        $array = array_merge(
            array_slice($array, 0, $pos),
            $insert,
            array_slice($array, $pos)
        );
    }
}

Integer usage:

$arr = ["one", "two", "three"];
array_insert(
    $arr,
    1,
    "one-half"
);
// ->
array (
  0 => 'one',
  1 => 'one-half',
  2 => 'two',
  3 => 'three',
)

String Usage:

$arr = [
    "name"  => [
        "type"      => "string",
        "maxlength" => "30",
    ],
    "email" => [
        "type"      => "email",
        "maxlength" => "150",
    ],
];

array_insert(
    $arr,
    "email",
    [
        "phone" => [
            "type"   => "string",
            "format" => "phone",
        ],
    ]
);
// ->
array (
  'name' =>
  array (
    'type' => 'string',
    'maxlength' => '30',
  ),
  'phone' =>
  array (
    'type' => 'string',
    'format' => 'phone',
  ),
  'email' =>
  array (
    'type' => 'email',
    'maxlength' => '150',
  ),
)

The `array_splice()` loses the keys, whereas `array_merge()` does not. So the results of the first function can be very surprising... Especially because if you have two elements with the same key, only the value of the last one is kept... — Alexis Wilke, Nov 20 '16 at 02:26

score 34 · Answer 3 · edited Dec 25 '15 at 16:11

34

$a = array(1, 2, 3, 4);
$b = array_merge(array_slice($a, 0, 2), array(5), array_slice($a, 2));
// $b = array(1, 2, 5, 3, 4)

edited Dec 25 '15 at 16:11

George Garchagudashvili

6,657
12
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answered Sep 26 '10 at 09:46

Amber

446,318
77
595
531

11

Using `+` instead of `array_merge` can preserve keys – mauris Jun 27 '12 at 06:57
1

Now I can add more elements before an INDEX – Abbas Apr 16 '18 at 05:41

score 6 · Answer 4 · answered Oct 05 '12 at 08:31

6

This way you can insert arrays:

function array_insert(&$array, $value, $index)
{
    return $array = array_merge(array_splice($array, max(0, $index - 1)), array($value), $array);
}

answered Oct 05 '12 at 08:31

Aleksandr Makov

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2

That function does not save the order in array. – Daniel Petrovaliev May 03 '16 at 11:44

score 6 · Answer 5 · answered Aug 12 '13 at 12:16

There is no native PHP function (that I am aware of) that can do exactly what you requested.

I've written 2 methods that I believe are fit for purpose:

function insertBefore($input, $index, $element) {
    if (!array_key_exists($index, $input)) {
        throw new Exception("Index not found");
    }
    $tmpArray = array();
    $originalIndex = 0;
    foreach ($input as $key => $value) {
        if ($key === $index) {
            $tmpArray[] = $element;
            break;
        }
        $tmpArray[$key] = $value;
        $originalIndex++;
    }
    array_splice($input, 0, $originalIndex, $tmpArray);
    return $input;
}

function insertAfter($input, $index, $element) {
    if (!array_key_exists($index, $input)) {
        throw new Exception("Index not found");
    }
    $tmpArray = array();
    $originalIndex = 0;
    foreach ($input as $key => $value) {
        $tmpArray[$key] = $value;
        $originalIndex++;
        if ($key === $index) {
            $tmpArray[] = $element;
            break;
        }
    }
    array_splice($input, 0, $originalIndex, $tmpArray);
    return $input;
}

While faster and probably more memory efficient, this is only really suitable where it is not necessary to maintain the keys of the array.

If you do need to maintain keys, the following would be more suitable;

function insertBefore($input, $index, $newKey, $element) {
    if (!array_key_exists($index, $input)) {
        throw new Exception("Index not found");
    }
    $tmpArray = array();
    foreach ($input as $key => $value) {
        if ($key === $index) {
            $tmpArray[$newKey] = $element;
        }
        $tmpArray[$key] = $value;
    }
    return $input;
}

function insertAfter($input, $index, $newKey, $element) {
    if (!array_key_exists($index, $input)) {
        throw new Exception("Index not found");
    }
    $tmpArray = array();
    foreach ($input as $key => $value) {
        $tmpArray[$key] = $value;
        if ($key === $index) {
            $tmpArray[$newKey] = $element;
        }
    }
    return $tmpArray;
}

This works fine. However, in the second example, in your function `insertBefore()`, you should return `$tmpArray` instead of `$input`. — Christoph Fischer, Oct 12 '17 at 13:20

score 6 · Answer 6 · answered Apr 27 '18 at 10:05

If you want to keep the keys of the initial array and also add an array that has keys, then use the function below:

function insertArrayAtPosition( $array, $insert, $position ) {
    /*
    $array : The initial array i want to modify
    $insert : the new array i want to add, eg array('key' => 'value') or array('value')
    $position : the position where the new array will be inserted into. Please mind that arrays start at 0
    */
    return array_slice($array, 0, $position, TRUE) + $insert + array_slice($array, $position, NULL, TRUE);
}

Call example:

$array = insertArrayAtPosition($array, array('key' => 'Value'), 3);

score 5 · Answer 7 · edited Mar 06 '13 at 09:47

5

function insert(&$arr, $value, $index){       
    $lengh = count($arr);
    if($index<0||$index>$lengh)
        return;

    for($i=$lengh; $i>$index; $i--){
        $arr[$i] = $arr[$i-1];
    }

    $arr[$index] = $value;
}

edited Mar 06 '13 at 09:47

nhahtdh

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answered Mar 06 '13 at 08:44

henry wong

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score 5 · Answer 8 · answered Oct 23 '14 at 04:46

Based on @Halil great answer, here is simple function how to insert new element after a specific key, while preserving integer keys:

private function arrayInsertAfterKey($array, $afterKey, $key, $value){
    $pos   = array_search($afterKey, array_keys($array));

    return array_merge(
        array_slice($array, 0, $pos, $preserve_keys = true),
        array($key=>$value),
        array_slice($array, $pos, $preserve_keys = true)
    );
}

score 4 · Answer 9 · answered Aug 16 '18 at 09:34

This is what worked for me for the associative array:

/*
 * Inserts a new key/value after the key in the array.
 *
 * @param $key
 *   The key to insert after.
 * @param $array
 *   An array to insert in to.
 * @param $new_key
 *   The key to insert.
 * @param $new_value
 *   An value to insert.
 *
 * @return
 *   The new array if the key exists, FALSE otherwise.
 *
 * @see array_insert_before()
 */
function array_insert_after($key, array &$array, $new_key, $new_value) {
  if (array_key_exists($key, $array)) {
    $new = array();
    foreach ($array as $k => $value) {
      $new[$k] = $value;
      if ($k === $key) {
        $new[$new_key] = $new_value;
      }
    }
    return $new;
  }
  return FALSE;
}

The function source - this blog post. There's also handy function to insert BEFORE specific key.

score 3 · Answer 10 · answered Jan 09 '14 at 17:25

This is also a working solution:

function array_insert(&$array,$element,$position=null) {
  if (count($array) == 0) {
    $array[] = $element;
  }
  elseif (is_numeric($position) && $position < 0) {
    if((count($array)+position) < 0) {
      $array = array_insert($array,$element,0);
    }
    else {
      $array[count($array)+$position] = $element;
    }
  }
  elseif (is_numeric($position) && isset($array[$position])) {
    $part1 = array_slice($array,0,$position,true);
    $part2 = array_slice($array,$position,null,true);
    $array = array_merge($part1,array($position=>$element),$part2);
    foreach($array as $key=>$item) {
      if (is_null($item)) {
        unset($array[$key]);
      }
    }
  }
  elseif (is_null($position)) {
    $array[] = $element;
  }  
  elseif (!isset($array[$position])) {
    $array[$position] = $element;
  }
  $array = array_merge($array);
  return $array;
}

credits go to: http://binarykitten.com/php/52-php-insert-element-and-shift.html

score 3 · Answer 11 · edited May 23 '17 at 12:03

3

if unsure, then DONT USE THESE:

$arr1 = $arr1 + $arr2;

OR

$arr1 += $arr2;

because with + original array will be overwritten. (see source)

edited May 23 '17 at 12:03

Community

1
1

answered May 03 '15 at 17:06

T.Todua

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score 3 · Answer 12 · answered Oct 20 '16 at 10:56

Solution by jay.lee is perfect. In case you want to add item(s) to a multidimensional array, first add a single dimensional array and then replace it afterwards.

$original = (
[0] => Array
    (
        [title] => Speed
        [width] => 14
    )

[1] => Array
    (
        [title] => Date
        [width] => 18
    )

[2] => Array
    (
        [title] => Pineapple
        [width] => 30
     )
)

Adding an item in same format to this array will add all new array indexes as items instead of just item.

$new = array(
    'title' => 'Time',
    'width' => 10
);
array_splice($original,1,0,array('random_string')); // can be more items
$original[1] = $new;  // replaced with actual item

Note: Adding items directly to a multidimensional array with array_splice will add all its indexes as items instead of just that item.

score 3 · Answer 13 · answered Feb 25 '17 at 09:24

3

You can use this

foreach ($array as $key => $value) 
{
    if($key==1)
    {
        $new_array[]=$other_array;
    }   
    $new_array[]=$value;    
}

answered Feb 25 '17 at 09:24

Devil

284
2
12

score 2 · Answer 14 · answered Mar 06 '13 at 16:22

2

Hint for adding an element at the beginning of an array:

$a = array('first', 'second');
$a[-1] = 'i am the new first element';

then:

foreach($a as $aelem)
    echo $a . ' ';
//returns first, second, i am...

but:

for ($i = -1; $i < count($a)-1; $i++)
     echo $a . ' ';
//returns i am as 1st element

answered Mar 06 '13 at 16:22

forsberg

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14

Hint for adding an element at the beginning: `array_unshift($a,'i am the new first element');` – Jul 04 '13 at 08:31

score 2 · Answer 15 · edited Mar 24 '16 at 22:03

Try this one:

$colors = array('red', 'blue', 'yellow');

$colors = insertElementToArray($colors, 'green', 2);


function insertElementToArray($arr = array(), $element = null, $index = 0)
{
    if ($element == null) {
        return $arr;
    }

    $arrLength = count($arr);
    $j = $arrLength - 1;

    while ($j >= $index) {
        $arr[$j+1] = $arr[$j];
        $j--;
    }

    $arr[$index] = $element;

    return $arr;
}

score 2 · Answer 16 · answered Jun 13 '19 at 11:23

function array_insert($array, $position, $insert) {
    if ($position > 0) {
        if ($position == 1) {
            array_unshift($array, array());
        } else {
            $position = $position - 1;
            array_splice($array, $position, 0, array(
                ''
            ));
        }
        $array[$position] = $insert;
    }

    return $array;
}

Call example:

$array = array_insert($array, 1, ['123', 'abc']);

score 1 · Answer 17 · answered Nov 25 '12 at 21:18

Normally, with scalar values:

$elements = array('foo', ...);
array_splice($array, $position, $length, $elements);

To insert a single array element into your array don't forget to wrap the array in an array (as it was a scalar value!):

$element = array('key1'=>'value1');
$elements = array($element);
array_splice($array, $position, $length, $elements);

otherwise all the keys of the array will be added piece by piece.

score 0 · Answer 18 · answered May 08 '12 at 16:16

For inserting elements into an array with string keys you can do something like this:

/* insert an element after given array key
 * $src = array()  array to work with
 * $ins = array() to insert in key=>array format
 * $pos = key that $ins will be inserted after
 */ 
function array_insert_string_keys($src,$ins,$pos) {

    $counter=1;
    foreach($src as $key=>$s){
        if($key==$pos){
            break;
        }
        $counter++;
    } 

    $array_head = array_slice($src,0,$counter);
    $array_tail = array_slice($src,$counter);

    $src = array_merge($array_head, $ins);
    $src = array_merge($src, $array_tail);

    return($src); 
}

why not `$src = array_merge($array_head, $ins, $array_tail);` ? — cartbeforehorse, May 30 '12 at 16:03

score 0 · Answer 19 · answered Nov 10 '20 at 01:16

This can be done with array_splice however, array_splice fails when inserting an array or using a string key. I wrote a function to handle all cases:

function array_insert(&$arr, $index, $val)
{
    if (is_string($index))
        $index = array_search($index, array_keys($arr));
    if (is_array($val))
        array_splice($arr, $index, 0, [$index => $val]);
    else
        array_splice($arr, $index, 0, $val);
}

Ann · Answer 20 · 2020-12-11T14:02:18.020

You can try it, use this method to make it easy

/**
 * array insert element on position
 * 
 * @link https://vector.cool
 * 
 * @since 1.01.38
 *
 * @param array $original
 * @param mixed $inserted
 * @param int   $position
 * @return array
 */
function array_insert(&$original, $inserted, int $position): array
{
    array_splice($original, $position, 0, array($inserted));
    return $original;
}


$columns = [
    ['name' => '預約項目', 'column' => 'item_name'],
    ['name' => '預約時間', 'column' => 'start_time'],
    ['name' => '預約姓名', 'column' => 'full_name'],
    ['name' => '連絡電話', 'column' => 'phone'],
    ['name' => '建立時間', 'column' => 'create_time']
];
$col = ['name' => '預約帳戶', 'column' => 'user_id'];
$columns = array_insert($columns, $col, 3);
print_r($columns);

Print out:

Array
(
    [0] => Array
        (
            [name] => 預約項目
            [column] => item_name
        )
    [1] => Array
        (
            [name] => 預約時間
            [column] => start_time
        )
    [2] => Array
        (
            [name] => 預約姓名
            [column] => full_name
        )
    [3] => Array
        (
            [name] => 報名人數1
            [column] => num_of_people
        )
    [4] => Array
        (
            [name] => 連絡電話
            [column] => phone
        )
    [5] => Array
        (
            [name] => 預約帳戶
            [column] => user_id
        )
    [6] => Array
        (
            [name] => 建立時間
            [column] => create_time
        )
)

Anthony Rutledge · Answer 21 · 2021-02-14T13:48:04.253

If you have regular arrays and nothing fancy, this will do. Remember, using array_splice() for inserting elements really means insert before the start index. Be careful when moving elements, because moving up means $targetIndex -1, where as moving down means $targetIndex + 1.

class someArrayClass
{
    private const KEEP_EXISTING_ELEMENTS = 0;

    public function insertAfter(array $array, int $startIndex, $newElements)
    {
        return $this->insertBefore($array, $startIndex + 1, $newElements);
    }

    public function insertBefore(array $array, int $startIndex, $newElements)
    {
        return array_splice($array, $startIndex, self::KEEP_EXISTING_ELEMENTS, $newElements);
    }
}

score 0 · Answer 22 · answered Feb 23 '21 at 21:05

0

$result_array = array();
$array = array("Tim","John","Mark");
$new_element = "Bill";
$position = 1; 

for ($i=0; $i<count($array); $i++)
    {
      if ($i==$position)
       {
          $result_array[] = $new_element;
       }
       $result_array[] = $array[$i];
    }

print_r($result_array); 

// Result will Array([0] => "Tim",[1] => "Bill", [2] => "John",[1] => "Mark")

answered Feb 23 '21 at 21:05

Тимофей Левендеев

27
2

Welcome to SO! Could you please add some description of what is the advantage of your solution? Thanks. – halanson Mar 04 '21 at 16:40

Insert new item in array on any position in PHP

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