PHP：由子值排序陣列

Question

可能重複：
How to sort arrays inside an array?
Sort an array by a child array's value in PHP

我有一個數組，看起來像這樣：

[0] => Array { 
    [ID] => 1651, 
    [DESCR] => "blabla", 
    [SORTNR] => 1, 
}, 
[1] => Array { 
    [ID] => 456, 
    [DESCR] => "bleble", 
    [SORTNR] => 3, 
}, 
[2] => Array { 
    [ID] => 158, 
    [DESCR] => "bliblablub", 
    [SORTNR] => 2, 
}, 

現在我想要使用值對子排列進行排序降序，所以在這裏它應該看起來像這樣：

[1] => Array { 
    [ID] => 456, 
    [DESCR] => "bleble", 
    [SORTNR] => 3, 
}, 
[2] => Array { 
    [ID] => 158, 
    [DESCR] => "bliblablub", 
    [SORTNR] => 2, 
}, 
[0] => Array { 
    [ID] => 1651, 
    [DESCR] => "blabla", 
    [SORTNR] => 1, 
}, 

我該如何在PHP中正確執行該操作？我現在嘗試了一些東西四個小時，我找不到任何好的解決方案....

Thx求助！改編自PHP uasort() manual page

Answer 1

function cmp($a, $b) { 
    if ($a['SORTNR'] == $b['SORTNR']) { 
    return 0; 
    } 
    return ($a['SORTNR'] < $b['SORTNR']) ? -1 : 1; 
} 

uasort($arr, 'cmp'); 

代碼如果要排序的子值是可變的，你也可以考慮使用array_multisort()。請參閱示例3：http://php.net/array_multisort

Answer 2