WeberTrivia.com -> PHP Manual -> Sort an array using a "natural order" algorithm

Description

bool natsort ( array &$array )

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". An example of the difference between this algorithm and the regular computer string sorting algorithms (used in sort()) can be seen in the example below.

Parameters

array: The input array.

Return Values

Returns TRUE on success or FALSE on failure.

Changelog

Version	Description
5.2.10	Zero padded numeric strings (e.g., '00005') now essentially ignore the 0 padding.

Examples

Example #1 natsort() examples demonstrating basic usage

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

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

natsort($array2);
echo "\nNatural order sorting\n";
print_r($array2);
?>

The above example will output:

 Standard sorting Array (     [3] => img1.png     [1] => img10.png     [0] => img12.png     [2] => img2.png )  Natural order sorting Array (     [3] => img1.png     [2] => img2.png     [1] => img10.png     [0] => img12.png )

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

Example #2 natsort() examples demonstrating potential gotchas

 <?php
echo "Negative numbers\n";
$negative = array('-5','3','-2','0','-1000','9','1');
print_r($negative);
natsort($negative);
print_r($negative);

echo "Zero padding\n";
$zeros = array('09', '8', '10', '009', '011', '0'); 
print_r($zeros);
natsort($zeros);
print_r($zeros);

echo "Other characters interfering\n";
$images_oops = array('image_1.jpg','image_12.jpg', 'image_21.jpg', 'image_4.jpg');
print_r($images_oops);
natsort($images_oops);
print_r($images_oops);

echo "Sort by keys\n";
$smoothie = array('orange' => 1, 'apple' => 1, 'yogurt' => 4, 'banana' => 4);
print_r($smoothie);
uksort( $smoothie, 'strnatcmp');
print_r($smoothie);
?>