sort an associative array by one of its keys

In case you need to sort an associative array by one of its keys, this function might be useful:

<?php
function sortByOneKey(array $array, $key, $asc = true) {
    $result = array();
       
    $values = array();
    foreach ($array as $id => $value) {
        $values[$id] = isset($value[$key]) ? $value[$key] : '';
    }
       
    if ($asc) {
        asort($values);
    }
    else {
        arsort($values);
    }
       
    foreach ($values as $key => $value) {
        $result[$key] = $array[$key];
    }
       
    return $result;
}

?>

Consider the following example:

<?php

$users = array(
    1 => array('name' => 'John', 'age' => 35),
    2 => array('name' => 'Alice', 'age' => 23),
    3 => array('name' => 'Bob', 'age' => 26)
);
       
$sortedByNameAsc = sortByOneKey($users, 'name');
$sortedByNameDesc = sortByOneKey($users, 'name', false);
       
echo "Sorted by Name in ascending order: ";
echo "<pre>" . print_r($sortedByNameAsc, true) . "</pre>";
echo "<br /><br />Sorted by Name in descending order: ";
echo "<pre>" . print_r($sortedByNameDesc, true) . "</pre>";

?>

The output will be the following:

Sorted by Name in ascending order:
Array
(
    [2] => Array
        (
            [name] => Alice
            [age] => 23
        )

    [3] => Array
        (
            [name] => Bob
            [age] => 26
        )

    [1] => Array
        (
            [name] => John
            [age] => 35
        )

)

Sorted by Name in descending order:
Array
(
    [1] => Array
        (
            [name] => John
            [age] => 35
        )

    [3] => Array
        (
            [name] => Bob
            [age] => 26
        )

    [2] => Array
        (
            [name] => Alice
            [age] => 23
        )

)