PHP を使用した多次元配列のソート

$array = array(
    array('price' => 45.50),
    array('price' => 15.00),
    array('price' => 20.15),
    array('price' => 25.00),
    array('price' => 90.10),
    array('price' => 9.99),
);

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

print_r($array);

Array (
    [0] => Array ( [price] => 9.99 )
    [1] => Array ( [price] => 15 )
    [2] => Array ( [price] => 20.15 )
    [3] => Array ( [price] => 25 )
    [4] => Array ( [price] => 45.5 )
    [5] => Array ( [price] => 90.1 )
)

$array = array(
    array('name' => 'John', 'age' => 25, 'score' => 80),
    array('name' => 'Mary', 'age' => 28, 'score' => 90),
    array('name' => 'Bob', 'age' => 20, 'score' => 95),
    array('name' => 'Jack', 'age' => 30, 'score' => 85),
    array('name' => 'Lisa', 'age' => 22, 'score' => 85),
);

// 按照年龄降序、分数升序、名字升序排序
usort($array, function($a, $b) {
    if ($a['age'] == $b['age']) {
        if ($a['score'] == $b['score']) {
            return strcmp($a['name'], $b['name']);
        } else {
            return ($a['score'] > $b['score']) ? 1 : -1;
        }
    } else {
        return ($a['age'] < $b['age']) ? 1 : -1;
    }
});

print_r($array);

Array (
    [0] => Array ( [name] => Mary [age] => 28 [score] => 90 )
    [1] => Array ( [name] => Jack [age] => 30 [score] => 85 )
    [2] => Array ( [name] => Lisa [age] => 22 [score] => 85 )
    [3] => Array ( [name] => John [age] => 25 [score] => 80 )
    [4] => Array ( [name] => Bob [age] => 20 [score] => 95 )
)