数组 函数
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rsort

(PHP 4, PHP 5)

rsort — 对数组逆向排序

说明

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

本函数对数组进行逆向排序（最高到最低）。

Note: 此函数为 array 中的元素赋与新的键名。这将删除原有的键名，而不是仅仅将键名重新排序。

成功时返回 TRUE， 或者在失败时返回 FALSE.

Example #1 rsort() 例子

<?php
$fruits = array("lemon", "orange", "banana", "apple");
rsort($fruits);
foreach ($fruits as $key => $val) {
    echo "$key = $val\n";
}
?>

以上例程会输出：

0 = orange
1 = lemon
2 = banana
3 = apple

fruits 被按照字母顺序逆向排序。

可以用可选参数 sort_flags 改变排序的行为，详情见 sort()。

参见 arsort()，asort()，ksort()，krsort()，sort() 和 usort()。

参数

array

The input array.

sort_flags

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

返回值

成功时返回 TRUE， 或者在失败时返回 FALSE.

范例

Example #2 rsort() example

<?php
$fruits = array("lemon", "orange", "banana", "apple");
rsort($fruits);
foreach ($fruits as $key => $val) {
    echo "$key = $val\n";
}
?>

以上例程会输出：

0 = orange
1 = lemon
2 = banana
3 = apple

The fruits have been sorted in reverse alphabetical order.

注释

Note: 此函数为 array 中的元素赋与新的键名。这将删除原有的键名，而不是仅仅将键名重新排序。

参见

数组 函数
在线手册：中文 英文
PHP手册
PHP手册 - N: 对数组逆向排序

用户评论:

Alex M (28-Jun-2005 03:39)

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
   }
?>

pshirkey at boosthardware dot com (14-Jan-2005 09:06)

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");

ray at non-aol dot com (02-Nov-2004 03:49)

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.

rnk-php at kleckner dot net (17-Jun-2003 08:37)

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.

slevy1 at pipeline dot com (13-Jun-2001 07:15)

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.