The array_chunk() function in PHP is used to split an array into smaller arrays (chunks) of a specified size. This function is particularly useful for processing large arrays in manageable pieces, allowing for better handling of data during iteration or display.

Syntax:

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

Parameters:

• $array: The input array that you want to split into chunks.
• $size: The size of each chunk (i.e., the number of elements in each smaller array).
• $preserve_keys: (Optional) A boolean value that determines whether to preserve the original keys of the array. The default value is false, which means the keys will be re-indexed starting from 0 in each chunk. If set to true, the original keys will be preserved in the chunks.

Return Value:

• The function returns a multidimensional array containing the chunks. Each chunk is an array itself, and if the input array is empty, it returns an empty array.

Example 1: Basic Usage

<?php
$array = range(1, 10); // Create an array with values from 1 to 10

// Split the array into chunks of size 3
$chunks = array_chunk($array, 3);
print_r($chunks);
?>

Output:

Array
(
    [0] => Array
        (
            [0] => 1
            [1] => 2
            [2] => 3
        )

    [1] => Array
        (
            [0] => 4
            [1] => 5
            [2] => 6
        )

    [2] => Array
        (
            [0] => 7
            [1] => 8
            [2] => 9
        )

    [3] => Array
        (
            [0] => 10
        )
)

In this example, the original array is split into chunks of 3 elements each.

Example 2: Preserving Keys

<?php
$array = array("a" => "Apple", "b" => "Banana", "c" => "Cherry", "d" => "Date");

// Split the array into chunks of size 2, preserving keys
$chunks = array_chunk($array, 2, true);
print_r($chunks);
?>

Output:

Array
(
    [0] => Array
        (
            [a] => Apple
            [b] => Banana
        )

    [1] => Array
        (
            [c] => Cherry
            [d] => Date
        )
)

In this example, the keys of the original array are preserved in the chunks.

Example 3: Chunking an Empty Array

<?php
$array = []; // An empty array

// Split the empty array into chunks
$chunks = array_chunk($array, 2);
print_r($chunks);
?>

Output:

Array
(
)

As expected, chunking an empty array returns an empty array.

Practical Usage:

• The array_chunk() function is useful in various scenarios, such as:
  • Paging through results in a web application.
  • Processing large datasets in smaller parts.
  • Dividing data for batch processing or display purposes.

Summary:

• array_chunk($array, $size, $preserve_keys) splits an array into smaller arrays (chunks) of a specified size.
• You can choose whether to preserve the original keys of the array in the chunks.
• This function is handy for handling large datasets and improving the manageability of array data in PHP.