//Just in one line custom function
function cmp($a, $b)
{
return (float) $a['price'] < (float)$b['price'];
}
@uasort($inventory, "cmp");
print_r($inventory);

//result

Array
(
[2] => Array
    (
        [type] => pork
        [price] => 5.43
    )

[0] => Array
    (
        [type] => fruit
        [price] => 3.5
    )

[1] => Array
    (
        [type] => milk
        [price] => 2.9
    )

)

从PHP 7.4开始，你可以使用arrow函数:

usort(
    $inventory, 
    fn(array $a, array $b): int => $b['price'] <=> $a['price']
);

代码(演示):

$inventory = [
    ['type' => 'fruit', 'price' => 3.50],
    ['type' => 'milk',  'price' => 2.90],
    ['type' => 'pork',  'price' => 5.43],
];

usort(
    $inventory, 
    fn(array $a, array $b): int => $b['price'] <=> $a['price']
);

print_r($inventory);

(浓缩)输出:

Array
(
    [0] => Array ([type] => pork,  [price] => 5.43)
    [1] => Array ([type] => fruit, [price] => 3.5)
    [2] => Array ([type] => milk,  [price] => 2.9)
)

适用于PHP 7及更高版本。

/**
 * A method for sorting associative arrays by a key and a direction.
 * Direction can be ASC or DESC.
 *
 * @param $array
 * @param $key
 * @param $direction
 * @return mixed $array
 */
function sortAssociativeArrayByKey($array, $key, $direction){

    switch ($direction){
        case "ASC":
            usort($array, function ($first, $second) use ($key) {
                return $first[$key] <=> $second[$key];
            });
            break;
        case "DESC":
            usort($array, function ($first, $second) use ($key) {
                return $second[$key] <=> $first[$key];
            });
            break;
        default:
            break;
    }

    return $array;
}

用法:

$inventory = sortAssociativeArrayByKey($inventory, "price", "ASC");

试试这个:

$prices = array_column($inventory, 'price');
array_multisort($prices, SORT_DESC, $inventory);
print_r($inventory);

$inventory = 
    array(array("type"=>"fruit", "price"=>3.50),
          array("type"=>"milk", "price"=>2.90),
          array("type"=>"pork", "price"=>5.43),
          );

function pricesort($a, $b) {
  $a = $a['price'];
  $b = $b['price'];
  if ($a == $b)
    return 0;
  return ($a > $b) ? -1 : 1;
}

usort($inventory, "pricesort");
// uksort($inventory, "pricesort");

print("first: ".$inventory[0]['type']."\n\n");
// for usort(): prints milk (item with lowest price)
// for uksort(): prints fruit (item with key 0 in the original $inventory)

// foreach prints the same for usort and uksort.
foreach($inventory as $i){
  print($i['type'].": ".$i['price']."\n");
}

输出:

first: pork

pork: 5.43
fruit: 3.5
milk: 2.9

如果需要对不同大小写的字符串数组进行排序，这将把排序数组的值更改为小写。

$data = [
    [
        'name' => 'jack',
        'eyeColor' => 'green'
    ],
    [
        'name' => 'Amy',
        'eyeColor' => 'brown'
    ],
    [   
        'name' => 'Cody',
        'eyeColor' => 'blue'
    ] 
];
function toLowerCase($a) { return strtolower($a); }
$sortArray = array_map("toLowerCase",array_column($data, 'name'));
array_multisort($sortArray, SORT_ASC, $data);