(PHP 4, PHP 5, PHP 7, PHP 8)
rsort — Sort an array in descending order
Sorts array in place by values
in descending order.
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: This function assigns new keys to the elements in
array. It will remove any existing keys that may have been assigned, rather than just reordering the keys.
Note:
Resets array's internal pointer to the first element.
arrayThe input array.
flags
The optional second parameter flags
may be used to modify the sorting behavior using these values:
Sorting type flags:
SORT_REGULAR - compare items normally;
the details are described in the comparison operators section
SORT_NUMERIC - compare items numerically
SORT_STRING - compare items as strings
SORT_LOCALE_STRING - compare items as
strings, based on the current locale. It uses the locale,
which can be changed using setlocale()
SORT_NATURAL - compare items as strings
using "natural ordering" like natsort()
SORT_FLAG_CASE - can be combined
(bitwise OR) with
SORT_STRING or
SORT_NATURAL to sort strings case-insensitively
Always returns true .
Example #1 rsort() example
<?php
$fruits = array("lemon", "orange", "banana", "apple");
rsort($fruits);
foreach ($fruits as $key => $val) {
echo "$key = $val\n";
}
?>The above example will output:
0 = orange 1 = lemon 2 = banana 3 = apple
The fruits have been sorted in reverse alphabetical order.
A cleaner (I think) way to sort a list of files into reversed order based on their modification date.
<?php
$path = $_SERVER[DOCUMENT_ROOT]."/files/";
$dh = @opendir($path);
while (false !== ($file=readdir($dh)))
{
if (substr($file,0,1)!=".")
$files[]=array(filemtime($path.$file),$file); #2-D array
}
closedir($dh);
if ($files)
{
rsort($files); #sorts by filemtime
#done! Show the files sorted by modification date
foreach ($files as $file)
echo "$file[0]$file[1]<br>\n"; #file[0]=Unix timestamp; file[1]=filename
}
?>Like sort(), rsort() assigns new keys for the elements in array. It will remove any existing keys you may have assigned, rather than just reordering the keys. This means that it will destroy associative keys.
$animals = array("dog"=>"large", "cat"=>"medium", "mouse"=>"small");
print_r($animals);
//Array ( [dog] => large [cat] => medium [mouse] => small )
rsort($animals);
print_r($animals);
//Array ( [0] => small [1] => medium [2] => large )
Use KSORT() or KRSORT() to preserve associative keys.