PHP数组函数映射数据技巧

$strings = ['1', '2', '3', '4', '5'];
$numbers = array_map('intval', $strings);
// 结果：[1, 2, 3, 4, 5]

$names = ['alice', 'bob', 'charlie'];
$formatted = array_map(function($name) {
    return ucfirst($name);
}, $names);
// 结果：['Alice', 'Bob', 'Charlie']

$users = [
    ['id' => 1, 'name' => 'Alice', 'email' => 'alice@example.com'],
    ['id' => 2, 'name' => 'Bob', 'email' => 'bob@example.com'],
];
$emails = array_column($users, 'email');
// 结果：['alice@example.com', 'bob@example.com']

$usersById = array_column($users, 'name', 'id');
// 结果：[1 => 'Alice', 2 => 'Bob']

$items = ['a', 'b', 'c'];
array_walk($items, function(&$value) {
    $value = 'prefix_' . $value;
});
// $items 变为 ['prefix_a', 'prefix_b', 'prefix_c']

$orders = [
    ['user' => 'Alice', 'amount' => 100],
    ['user' => 'Bob',   'amount' => 200],
    ['user' => 'Alice', 'amount' => 150],
];

$userNames = array_column($orders, 'user');
$uniqueUsers = array_unique($userNames);
$cleaned = array_values($uniqueUsers); // 重置索引