PHP array_unshift function

The PHP function array_unshift inserts one or more elements at the beginning of the array.

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

$narray = array_unshift($array,$value);

Numeric arrays will be modified to start from 0.

Parameters

$array – the array to which new elements will be added to the left.

$values – the values we will add.

Returns

int – returns the number of new elements in the array.

PHP array_unshift examples

$pearson = array(
    "nombre" => "Juan",
    "edad" => 25,
    "ciudad" => "EjemploCity"
);
array_unshift($pearson,"Paraguay");

print_r($pearson);

Array
(
    [0] => Paraguay
    [nombre] => Juan
    [edad] => 25
    [ciudad] => EjemploCity
)

Numeric array example:

$numeros = array(10, 20, 30, 40, 50);
array_unshift($numeros,1,2);
print_r($numeros);

Array
(
    [0] => 1
    [1] => 2
    [2] => 10
    [3] => 20
    [4] => 30
    [5] => 40
    [6] => 50
)

Uses

Queue Management: If you are implementing a queue of elements and need to insert new elements at the beginning of the queue so that they are processed first, array_unshift can be useful.

$queue = array();
array_unshift($queue, "Nuevo elemento");

History or Stack Handling: In situations where you are building a history or a stack of elements and want to add new elements at the top so that they are the most recent ones.

$history = array("Elemento antiguo");
array_unshift($history, "Nuevo elemento");

Normally, you would push and pop in a stack, but you could also do something like this if there are elements you want to remove from the end.