Change language:

natcasesort

(PHP 4, PHP 5, PHP 7, PHP 8)

natcasesort — Sort an array using a case insensitive "natural order" algorithm

Description

function natcasesort(array &$array): true

natcasesort() is a case insensitive version of natsort().

This function implements a sort algorithm that orders alphanumeric strings in the way a human being would while maintaining key/value associations. This is described as a "natural ordering".

Note: If two members compare as equal, they retain their original order. Prior to PHP 8.0.0, their relative order in the sorted array was undefined.

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

Parameters

array: The input array.

Return Values

Always returns true.

Changelog

Version	Description
8.2.0	The return type is `true` now; previously, it was bool.

Examples

Example #1 natcasesort() example

<?php
$array1 = $array2 = array('IMG0.png', 'img12.png', 'img10.png', 'img2.png', 'img1.png', 'IMG3.png');

sort($array1);
echo "Standard sorting\n";
print_r($array1);

natcasesort($array2);
echo "\nNatural order sorting (case-insensitive)\n";
print_r($array2);
?>

The above example will output:

Standard sorting
Array
(
    [0] => IMG0.png
    [1] => IMG3.png
    [2] => img1.png
    [3] => img10.png
    [4] => img12.png
    [5] => img2.png
)

Natural order sorting (case-insensitive)
Array
(
    [0] => IMG0.png
    [4] => img1.png
    [3] => img2.png
    [5] => IMG3.png
    [2] => img10.png
    [1] => img12.png
)

For more information see: Martin Pool's » Natural Order String Comparison page.

Found A Problem?

Learn How To Improve This Page • Submit a Pull Request • Report a Bug

＋add a note

User Contributed Notes 1 note

down

dslicer at maine dot rr dot com ¶

23 years ago

Something that should probably be documented is the fact that both natsort and natcasesort maintain the key-value associations of the array. If you natsort a numerically indexed array, a for loop will not produce the sorted order; a foreach loop, however, will produce the sorted order, but the indices won't be in numeric order. If you want natsort and natcasesort to break the key-value associations, just use array_values on the sorted array, like so:

natcasesort($arr);
$arr = array_values($arr);