PHP Manual: Prepend one or more elements to the beginning of an array

Description

int array_unshift(array &$array, mixed ...$values)

array_unshift prepends passed elements to the front of the array. Note that the list of elements is prepended as a whole, so that the prepended elements stay in the same order. All numerical array keys will be modified to start counting from zero while literal keys won't be changed.

Note:
Resets array's internal pointer to the first element.

Parameters

array: The input array.
values: The values to prepend.

Return Values

Returns the new number of elements in the array.

Changelog

Version	Description
7.3.0	This function can now be called with only one parameter. Formerly, at least two parameters have been required.

Examples

Example #1 array_unshift example

<?php

$queue = [
    "orange",
    "banana"
];

array_unshift($queue, "apple", "raspberry");

var_dump($queue);

?>

The above example will output:

array(4) {
  [0] =>
  string(5) "apple"
  [1] =>
  string(9) "raspberry"
  [2] =>
  string(6) "orange"
  [3] =>
  string(6) "banana"
}

Example #2 Usage with associative arrays

If one associative array is prepended to another associative array, the prepended array is numerically indexed into the former array.

<?php

$foods = [
    'apples' => [
        'McIntosh' => 'red',
        'Granny Smith' => 'green',
    ],
    'oranges' => [
        'Navel' => 'orange',
        'Valencia' => 'orange',
    ],
];

$vegetables = [
    'lettuce' => [
        'Iceberg' => 'green',
        'Butterhead' => 'green',
    ],
    'carrots' => [
        'Deep Purple Hybrid' => 'purple',
        'Imperator' => 'orange',
    ],
    'cucumber' => [
        'Kirby' => 'green',
        'Gherkin' => 'green',
    ],
];

array_unshift($foods, $vegetables);

var_dump($foods);

?>