[php] Insert new item in array on any position in PHP

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

if unsure, then DONT USE THESE:

$arr1 = $arr1 + $arr2;

OR

$arr1 += $arr2;

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

$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")

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);

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.

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

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); 
} 

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;
}

$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)

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

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' => '????', 'column' => 'item_name'],
    ['name' => '????', 'column' => 'start_time'],
    ['name' => '????', 'column' => 'full_name'],
    ['name' => '????', 'column' => 'phone'],
    ['name' => '????', 'column' => 'create_time']
];
$col = ['name' => '????', 'column' => 'user_id'];
$columns = array_insert($columns, $col, 3);
print_r($columns);

Print out:

Array
(
    [0] => Array
        (
            [name] => ????
            [column] => item_name
        )
    [1] => Array
        (
            [name] => ????
            [column] => start_time
        )
    [2] => Array
        (
            [name] => ????
            [column] => full_name
        )
    [3] => Array
        (
            [name] => ????1
            [column] => num_of_people
        )
    [4] => Array
        (
            [name] => ????
            [column] => phone
        )
    [5] => Array
        (
            [name] => ????
            [column] => user_id
        )
    [6] => Array
        (
            [name] => ????
            [column] => create_time
        )
)

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;
}

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);
}

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);
}

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;
}

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);
    }
}

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.

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']);

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',
  ),
)

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)
    );
} 

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.

You can use this

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