Using PHP’s array_chunk() Function to Split Arrays

In PHP development, splitting a large array into smaller arrays of a given size is a common task, and the array_chunk() function is designed for this purpose.

The syntax of the function is:

array array_chunk ( array $array , int $size [, bool $preserve_keys = false ] )

The function accepts three parameters: $array – the input array to be split; $size – the desired size of each chunk; and $preserve_keys – a boolean that determines whether the original keys are retained in the resulting chunks.

A basic example splits an array into chunks of three elements:

<?php
$array = array('a','b','c','d','e','f','g','h','i','j');
$chunks = array_chunk($array, 3);
print_r($chunks);
?>

The output shows four sub‑arrays, the first three containing three elements each and the last containing the remaining element:

Array
(
    [0] => Array
        (
            [0] => a
            [1] => b
            [2] => c
        )

    [1] => Array
        (
            [0] => d
            [1] => e
            [2] => f
        )

    [2] => Array
        (
            [0] => g
            [1] => h
            [2] => i
        )

    [3] => Array
        (
            [0] => j
        )

)

When the third argument $preserve_keys is set to true , the original keys are kept. The following example demonstrates this behavior:

<?php
$array = array('a' => 1, 'b' => 2, 'c' => 3, 'd' => 4, 'e' => 5, 'f' => 6);
$chunks = array_chunk($array, 2, true);
print_r($chunks);
?>

The resulting array consists of three sub‑arrays, each preserving the original associative keys:

Array
(
    [0] => Array
        (
            [a] => 1
            [b] => 2
        )

    [1] => Array
        (
            [c] => 3
            [d] => 4
        )

    [2] => Array
        (
            [e] => 5
            [f] => 6
        )

)

In summary, array_chunk() is a practical PHP function for dividing large arrays into smaller pieces, with optional key preservation, making it useful for handling extensive data sets in backend development.