(PHP 4, PHP 5, PHP 7, PHP 8)
natcasesort — Sort an array using a case insensitive "natural order" algorithm
DescriptionThis 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.
ParametersNote:
Resets array's internal pointer to the first element.
array
The input array.
Always returns true.
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($array2);
?>
The above example will output:
Standard sorting
Array
(
[0] => IMG0.png
[1] => IMG3.png
[2] => img1.png
[3] => img10.png
[4] => img12.png
[5] => img2.png
)
Natural order sorting (case-insensitive)
Array
(
[0] => IMG0.png
[4] => img1.png
[3] => img2.png
[5] => IMG3.png
[2] => img10.png
[1] => img12.png
)
For more information see: Martin Pool's » Natural Order String Comparison page.
dslicer at maine dot rr dot com ¶22 years ago
Something that should probably be documented is the fact that both natsort and natcasesort maintain the key-value associations of the array. If you natsort a numerically indexed array, a for loop will not produce the sorted order; a foreach loop, however, will produce the sorted order, but the indices won't be in numeric order. If you want natsort and natcasesort to break the key-value associations, just use array_values on the sorted array, like so:
natcasesort($arr);
$arr = array_values($arr); w-dot-rosenbach-at-netskill-de ¶
14 years ago
Sorting UTF-8 by arbitrary order:
<?php
mb_internal_encoding("UTF-8");
class
utf_8_german
{
static $order = '0123456789AaÄäBbCcDdEeFfGgHhIiJjKkLlMm
NnOoÖöPpQqRrSsßTtUuÜüVvWwXxYyZz';
static $char2order;
static function
cmp($a, $b) {
if ($a == $b) {
return 0;
} if (empty(self::$char2order))
{
$order = 1;
$len = mb_strlen(self::$order);
for ($order=0; $order<$len; ++$order)
{
self::$char2order[mb_substr(self::$order, $order, 1)] = $order;
}
} $len_a = mb_strlen($a);
$len_b = mb_strlen($b);
$max=min($len_a, $len_b);
for($i=0; $i<$max; ++$i)
{
$char_a= mb_substr($a, $i, 1);
$char_b= mb_substr($b, $i, 1);
if (
$char_a == $char_b) continue;
$order_a = (isset(self::$char2order[$char_a])) ? self::$char2order[$char_a] : 9999;
$order_b = (isset(self::$char2order[$char_b])) ? self::$char2order[$char_b] : 9999;
return (
$order_a < $order_b) ? -1 : 1;
}
return ($len_a < $len_b) ? -1 : 1;
}
} $t = array(
'Birnen', 'Birne', 'Äpfel', 'Apfel',
); uasort($t, 'utf_8_german::cmp');
echo '$t: <pre>'.htmlspecialchars(print_r($t,true),null,'UTF-8').'</pre>';
?>
claude at schlesser dot lu ¶
16 years ago
Here a function that will natural sort an array by keys with keys that contain special characters.
<?php
function natksort($array)
{
$original_keys_arr = array();
$original_values_arr = array();
$clean_keys_arr = array(); $i = 0;
foreach ($array AS $key => $value)
{
$original_keys_arr[$i] = $key;
$original_values_arr[$i] = $value;
$clean_keys_arr[$i] = strtr($key, "ÄÖÜäöüÉÈÀËëéèàç", "AOUaouEEAEeeeac");
$i++;
} natcasesort($clean_keys_arr); $result_arr = array();
foreach (
$clean_keys_arr AS $key => $value)
{
$original_key = $original_keys_arr[$key];
$original_value = $original_values_arr[$key];
$result_arr[$original_key] = $original_value;
}
return
$result_arr;
}
?>
Hope it will be useful to somebody :) vbAlexDOSMan at Yahoo dot com ¶
21 years ago
Ulli at Stemmeler dot net: I remade your function -- it's a little more compact now -- Enjoy...
function ignorecasesort(&$array) {
/*Make each element it's lowercase self plus itself*/
/*(e.g. "MyWebSite" would become "mywebsiteMyWebSite"*/
for ($i = 0; $i < sizeof($array); $array[$i] = strtolower($array[$i]).$array[$i], $i++);
/*Sort it -- only the lowercase versions will be used*/
sort($array);
/*Take each array element, cut it in half, and add the latter half to a new array*/
/*(e.g. "mywebsiteMyWebSite" would become "MyWebSite")*/
for ($i = 0; $i < sizeof($array); $i++) {
$this = $array[$i];
$array[$i] = substr($this, (strlen($this)/2), strlen($this));
}
} tmiller25 at hotmail dot com ¶
23 years ago
add this loop to the function above if you want items which have the same first characters to be listed in a way that the shorter string comes first.
--------------------
/* short before longer (e.g. 'abc' should come before 'abcd') */
for($i=count($array)-1;$i>0;$i--) {
$str_a = $array[$i ];
$str_b = $array[$i-1];
$cmp_a = strtolower(substr($str_a,0,strlen($str_a)));
$cmp_b = strtolower(substr($str_b,0,strlen($str_a)));
if ($cmp_a==$cmp_b && strlen($str_a)<strlen($str_b)) {
$array[$i]=$str_b; $array[$i-1]=$str_a; $i+=2;
}
}
--------------------
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