PHP数组按条件排序

$data = array(
    'apple' => 10,
    'banana' => 5,
    'cherry' => 20,
    'date' => 15
);

// 使用arsort()函数按值降序排序
arsort($data);

print_r($data);

Array
(
    [cherry] => 20
    [date] => 15
    [apple] => 10
    [banana] => 5
)

$data = array(
    array('name' => 'Alice', 'age' => 25),
    array('name' => 'Bob', 'age' => 30),
    array('name' => 'Charlie', 'age' => 20)
);

// 自定义比较函数
function sortByAge($a, $b) {
    return $a['age'] - $b['age'];
}

// 使用usort()函数和自定义比较函数排序
usort($data, 'sortByAge');

print_r($data);

Array
(
    [0] => Array
        (
            [name] => Charlie
            [age] => 20
        )

    [1] => Array
        (
            [name] => Alice
            [age] => 25
        )

    [2] => Array
        (
            [name] => Bob
            [age] => 30
        )
)