PHP Unconference Europe 2015

rsort

(PHP 4, PHP 5)

rsort Sortiert ein Array in umgekehrter Reihenfolge

Beschreibung

bool rsort ( array &$array [, int $sort_flags = SORT_REGULAR ] )

Diese Funktion sortiert ein Array in umgekehrter Reihenfolge (vom höchsten zum niedrigsten Wert).

Parameter-Liste

array

Das Eingabe-Array.

sort_flags

Sie können das Verhalten der Sortierung mittels dem optionalen Parameter sort_flags beeinflussen, für Details siehe sort().

Rückgabewerte

Gibt bei Erfolg TRUE zurück. Im Fehlerfall wird FALSE zurückgegeben.

Beispiele

Beispiel #1 rsort()-Beispiel

<?php
$fruits 
= array("Orange""Apfel""Zitrone""Banane");
rsort($fruits);
foreach (
$fruits as $key => $val) {
    echo 
"$key = $val\n";
}
?>

Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

0 = Zitrone
1 = Orange
2 = Banane
3 = Apfel

Die Früchte wurden in umgekehrter alphabetischer Reihenfolge sortiert.

Anmerkungen

Hinweis: Diese Funktion weist den Elementen des Arrays array neue Schlüssel zu. Bestehende Schlüssel, die Sie eventuell zugewiesen haben, werden entfernt statt einfach nur die Schlüssel neu anzuordnen

Siehe auch

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User Contributed Notes 6 notes

up
5
ray at non-aol dot com
9 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
2
Alex M
9 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
  
}
?>
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2
slevy1 at pipeline dot com
13 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
1
pshirkey at boosthardware dot com
9 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
-1
suniafkhami at gmail dot com
8 months 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]
up
-4
rnk-php at kleckner dot net
11 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.
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