PHP 8.4.0 Alpha 2 available for testing

rsort

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

rsortOrdina un array in ordine decrescente

Descrizione

rsort(array $array, int $sort_flags = ?): bool

Questa funzione ordina un array in ordine decrescente.

Restituisce true in caso di successo, false in caso di fallimento.

Example #1 esempio di rsort()

<?php
$frutti
= array("limone", "arancia", "banana", "mela");
rsort($frutti);
reset($frutti);
while (list(
$chiave, $valore) = each($frutti)) {
echo
"$chiave = $valore\n";
}
?>

Questo esempio mostrerà:

0 = mela
1 = limone
2 = banana
3 = arancia

I frutti sono stati ordinati in ordine alfabetico decrescente.

Si può modificare il comportamento dell'ordinamento usando il parametro opzionale sort_flags, per maggiori dettagli vedere sort().

Vedere anche arsort(), asort(), ksort(), sort() e usort().

add a note

User Contributed Notes 6 notes

up
4
Alex M
19 years ago
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
}
?>
up
1
ray at non-aol dot com
19 years ago
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.
up
-5
slevy1 at pipeline dot com
23 years ago
I thought rsort was working successfully or on a multi-dimensional array of strings that had first been sorted with usort(). But, I noticed today that the array was only partially in descending order. I tried array_reverse on it and that seems to have solved things.
up
-8
pshirkey at boosthardware dot com
19 years ago
I needed a function that would sort a list of files into reversed order based on their modification date.

Here's what I came up with:

function display_content($dir,$ext){

$f = array();
if (is_dir($dir)) {
if ($dh = opendir($dir)) {
while (($folder = readdir($dh)) !== false) {
if (preg_match("/\s*$ext$/", $folder)) {
$fullpath = "$dir/$folder";
$mtime = filemtime ($fullpath);

$ff = array($mtime => $fullpath);
$f = array_merge($f, $ff);

}
}



rsort($f, SORT_NUMERIC);

while (list($key, $val) = each($f)) {
$fcontents = file($val, "r");
while (list($key, $val) = each($fcontents))
echo "$val\n";
}

}
}

closedir($dh);
}

Call it like so:

display_content("folder","extension");
up
-10
rnk-php at kleckner dot net
21 years ago
Apparently rsort does not put arrays with one value back to zero. If you have an array like: $tmp = array(9 => 'asdf') and then rsort it, $tmp[0] is empty and $tmp[9] stays as is.
up
-13
suniafkhami at gmail dot com
10 years ago
If you are sorting an array from a database result set, such as MySQL for example, another approach could be to have your database sort the result set by using ORDER BY DESC, which would be the equivalent of using rsort() on the resulting array in PHP.

[Edited by moderator for clarity: googleguy at php dot net]
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