PHP 8.4.1 Released!

    rsort

    (PHP 4, PHP 5, PHP 7, PHP 8)

    rsort — 对数组降序排序

    说明

    rsort(array &$array, int $flags = SORT_REGULAR): true

    对 array 本身按照值（value）降序排序。

    注意:

    如果两个成员完全相同，那么它们将保持原来的顺序。 在 PHP 8.0.0 之前，它们在排序数组中的相对顺序是未定义的。

    注意: 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。

    注意:

    重置数组中的内部指针，指向第一个元素。

    参数

    array

    输入的数组。

    flags

    可选的第二个参数 flags 可以用以下值改变排序的行为：

    排序类型标记：

    返回值

    总是返回 true。

    更新日志

    版本 说明
    8.2.0 现在返回类型为 true；之前是 bool。

    示例

    示例 #1 rsort() 示例

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

    以上示例会输出：

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

    fruits 被按照字母顺序逆向排序。

    注释

    注意: 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

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    用户贡献的备注 3 notes

    up
    5
    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
    0
    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
    -4
    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.
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