PHP Array Push Function: A Comprehensive Guide

array_push() adds one or more elements to the end of an array, treating that array like a stack. It is the everyday way to grow a list in PHP, and it returns the new number of elements once the values have been added.

This page covers the syntax, the value array_push() returns, how it behaves with associative and empty arrays, the faster [] shorthand, and the related functions for removing or prepending elements.

Syntax

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

• $array — the array to modify. It is passed by reference (&), so the original variable is changed in place; you don't reassign it.
• $values — one or more values to append, in the order given.
• Return value — the new length of the array (an integer).

Basic example

The example below starts with three fruits and appends two more:

The new values are added in order, and $count holds the updated length:

5
Array
(
    [0] => apple
    [1] => banana
    [2] => cherry
    [3] => orange
    [4] => peach
)

The [] shorthand for a single value

If you only need to append one element, the $array[] = $value syntax does the same thing and is faster, because it avoids the overhead of a function call:

<?php

$colors = array("red", "green");
$colors[] = "blue"; // same as array_push($colors, "blue")
print_r($colors);

?>

Array
(
    [0] => red
    [1] => green
    [2] => blue
)

Reach for array_push() when you need to add several values at once; use [] for a single value.

Behavior with keys

array_push() always re-indexes the appended values with new integer keys, continuing from the array's highest existing integer key. Existing string (associative) keys are left untouched:

<?php

$data = array("name" => "Ann", 5 => "five");
array_push($data, "added");
print_r($data);

?>

Array
(
    [name] => Ann
    [5] => five
    [6] => added
)

Notice the new element became [6] — one past the largest integer key (5), not [2].

Pushing onto an empty array

You don't need to declare keys first. Pushing onto an empty array starts the numbering at 0:

<?php

$list = array();
array_push($list, "first", "second");
print_r($list);

?>

Array
(
    [0] => first
    [1] => second
)

Common gotchas

• It modifies in place. Because the array is passed by reference, do not write $arr = array_push($arr, $x) — that would overwrite your array with the integer length. Call array_push($arr, $x) on its own line.
• The argument must be a variable. Since the parameter is by reference, you cannot push onto a literal like array_push(array(), "x").
• Use [] for one value. For a single element, $arr[] = $value is clearer and a bit faster.

Related functions

• array_pop() — removes and returns the last element (the opposite of pushing).
• array_unshift() — adds elements to the beginning of an array.
• array_shift() — removes the first element.
• array_merge() — combines two or more arrays into one.
• array_splice() — inserts or removes elements at any position.

Practice