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    rsort

    (PHP 4, PHP 5, PHP 7)

    rsort — 역순으로 배열 정렬

    설명

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

    이 함수는 역순으로 배열을 정렬한다 (높은 것에서 낮은 것으로).

    인수

    array

    입력 배열.

    sort_flags

    선택적인 인수 sort_flags를 사용하여 정렬 방법을 변경할수 있다. 더 자세한 것은 sort() 를 참고.

    반환값

    성공 시 TRUE를, 실패 시 FALSE를 반환합니다.

    예제

    Example #1 rsort() 예제

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

    위 예제의 출력:

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

    fruits는 알파벳 역순으로 정렬되었다.

    주의

    Note: 이 함수는 array에 새로운 키를 할당합니다. 이 작업은 단순히 키를 재배열할 뿐만 아니라, 이미 할당되어 있는 키를 제거할 수 있습니다.

    참고

    • arsort() - 배열을 내림차순 정렬하고 인덱스의 상관관계를 유지
    • asort() - 배열을 정렬하고 인덱스 상관 관계를 유지
    • ksort() - 키에 의한 배열 정렬
    • krsort() - 키에 의한 배열 역순 정렬
    • sort() - 배열 정렬
    • usort() - 사용자 정의 비교 함수를 사용하여 값에 의한 배열 정렬

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    User Contributed Notes 6 notes

    up
    3
    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
    2
    ray at non-aol dot com
    20 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
    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
    -3
    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
    -7
    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
    -9
    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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