$v2 ? 1 : -1;}$res=usort($arr, 'func');print_r($arr);//输出：Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => 5 [5] => 6 [6] => 7 )*///uasort()通过自定义函数对数组进行排序，原数组索引保留/*$arr = array('5' => 5, '3' => 3, '7' => 7, '6' => 6, '4' => 4, '1' => 1, '2' => 2);function func($v1, $v2){    if ($v1 == $v2) return 0;    return $v1 > $v2 ? 1 : -1;}$res = @uasort($arr, 'func');print_r($arr);//输出：Array ( [1] => 1 [2] => 2 [3] => 3 [4] => 4 [5] => 5 [6] => 6 [7] => 7 )*///uksort() 通过调用自定义函数对数组的键名进行排序。$arr = array('9' => 5, '20' => 3, '2' => 7, '7' => 6);function func($v1, $v2){    if ($v1 == $v2) return 0;    return $v1 > $v2 ? 1 : -1; //1在前，升序。1在后降序}$res = @uksort($arr, 'func');print_r($arr);//输出：Array ( [2] => 7 [7] => 6 [9] => 5 [20] => 3 )