PHP 7.0.6 Released

    rsort

    (PHP 4, PHP 5, PHP 7)

    rsort — Sort an array in reverse order

    Description

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

    This function sorts an array in reverse order (highest to lowest).

    Parameters

    array

    The input array.

    sort_flags

    You may modify the behavior of the sort using the optional parameter sort_flags, for details see sort().

    Return Values

    Returns TRUE on success or FALSE on failure.

    Examples

    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.

    Notes

    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.

    See Also

    User Contributed Notes

    ray at non-aol dot com
    11 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.
    pshirkey at boosthardware dot com
    11 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");
    Alex M
    10 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
           }
    ?>
    slevy1 at pipeline dot com
    14 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.
    suniafkhami at gmail dot com
    2 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]
    rnk-php at kleckner dot net
    12 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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