How to maintain key names in sorted array using PHP?

To maintain the key names of the sorted array, you can use the following method: use ksort() and krsort() to sort by key and maintain the key order. Use array_multisort() to sort based on multiple columns (including keys) simultaneously. Define custom comparator functions to control collation.

#How to maintain key names in a sorted array using PHP?

Sometimes, after sorting an array in PHP, you want to maintain the original key names. Here's how to do it:

Using the ksort() and krsort() functions

ksort () and krsort() sort arrays by key. These functions maintain key names in ascending and descending order respectively:

// 按键升序排序
$array = ['name' => 'John', 'age' => 30, 'city' => 'New York'];
ksort($array);

// 按键降序排序
$array = ['name' => 'John', 'age' => 30, 'city' => 'New York'];
krsort($array);

Using array_multisort() Function

array_multisort() Multiple array columns can be sorted at the same time, including keys:

// 按键升序排序，如果键相等则按值降序排序
$names = ['name1', 'name3', 'name5', 'name2', 'name4'];
$ages = [20, 30, 50, 40, 60];

array_multisort($names, SORT_ASC, SORT_NUMERIC, $ages, SORT_DESC);

Using a custom comparator

You can define your own comparator function to control the sorting rules , including keys:

function compareKeys($a, $b) {
    return strcmp($a['key'], $b['key']);
}

$array = [{'key' => 'a'}, {'key' => 'c'}, {'key' => 'b'}];
usort($array, 'compareKeys');

Practical case: Sorting users by key

// 获取用户数据
$users = [
    ['id' => 1, 'name' => 'John Doe'],
    ['id' => 3, 'name' => 'Jane Smith'],
    ['id' => 2, 'name' => 'Bob Johnson']
];

// 使用 ksort 按键升序排序用户
ksort($users);

// 按升序的键输出用户列表
foreach ($users as $user) {
    echo $user['id'] . ': ' . $user['name'] . '<br>';
}

This code will output a user list sorted by id in ascending order, retaining the original key names .

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