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PHP : Function Reference : Array Functions : rsort

rsort

Sort an array in reverse order (PHP 4, PHP 5)
bool rsort ( array &array [, int sort_flags] )

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

Note:

This function assigns new keys for the elements in array. It will remove any existing keys you may have assigned, rather than just reordering the keys.

Returns TRUE on success or FALSE on failure.

Example 321. 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.

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

See also arsort(), asort(), ksort(), krsort(), sort(), and usort().

Related Examples ( Source code ) » rsort



Code Examples / Notes » rsort

ray

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.


slevy1

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.

pshirkey

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");


rnk-php

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.

alex m

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]
\n";  #file[0]=Unix timestamp; file[1]=filename
  }
?>


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