PHP排序多维数组的值，其中有NULL使用wassort

Question

我创建了一个像

这样的数组

$arr[0]['ref']=5;
$arr[0]['name']='name0';
$arr[1]['ref']=6;
$arr[1]['name']='name1';
$arr[2]['ref']=4;
$arr[2]['name']='name2';
$arr[3]['ref']='';
$arr[3]['name']='name3';
$arr[4]['ref']='9';
$arr[4]['name']='name4';
$arr[5]['ref']=''
$arr[5]['name']='name5'

我想用ref value

排序这个数组

$arr[2]['ref']=4;
$arr[2]['name']='name2';
$arr[0]['ref']=5;
$arr[0]['name']='name0';
$arr[1]['ref']=6;
$arr[1]['name']='name1';
$arr[4]['ref']='9';
$arr[4]['name']='name4';
$arr[3]['ref']='';
$arr[3]['name']='name3';
$arr[5]['ref']=''
$arr[5]['name']='name5'

i tried

uasort($arr, function($a, $b){
    return $a['ref'] - $b['ref'];
});

但是"值是从一开始就出现的。"我怎么能推下去呢?

提前感谢。我是初学者。请原谅，如果我问一个非常简单的问题

Answer 1

这就行了:

uasort($arr, function($a, $b){
    if ($a['ref'] == "") return 1;
    if ($b['ref'] == "") return -1;
    return $a['ref'] - $b['ref'];
});

Answer 2

你可以试试

uasort($arr, function($a, $b){
    return -($a['ref'] - $b['ref']);
});

Answer 3

可以在数组的末尾添加空值:

uasort($arr, function($a, $b){
   return $a['ref'] - $b['ref'];
});
//strip empties and move to end
foreach ($arr as $key => $value)
{ 
    if ($value['ref'] == "")
    { 
        unset($arr[$key]);
        $arr[] = $value;
    }
}
// rebuild array index
$arr = array_values($arr);

输出:

Array
(
    [0] => Array
        (
            [ref] => 4
            [name] => name2
        )
    [1] => Array
        (
            [ref] => 5
            [name] => name0
        )
    [2] => Array
        (
            [ref] => 6
            [name] => name1
        )
    [3] => Array
        (
            [ref] => 9
            [name] => name4
        )
    [4] => Array
        (
            [ref] => 
            [name] => name5
        )
    [5] => Array
        (
            [ref] => 
            [name] => name3
        )
)