(PHP 4, PHP 5, PHP 7, PHP 8)
natsort — Sort an array using a "natural order" algorithm
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.
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.
arrayThe input array.
Always returns true.
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);
?>The above example will output:
Negative numbers
Array
(
[0] => -5
[1] => 3
[2] => -2
[3] => 0
[4] => -1000
[5] => 9
[6] => 1
)
Array
(
[2] => -2
[0] => -5
[4] => -1000
[3] => 0
[6] => 1
[1] => 3
[5] => 9
)
Zero padding
Array
(
[0] => 09
[1] => 8
[2] => 10
[3] => 009
[4] => 011
[5] => 0
)
Array
(
[5] => 0
[1] => 8
[3] => 009
[0] => 09
[2] => 10
[4] => 011
)