Parcours dimensionnel du tri de tableaux multidimensionnels PHP : d'une dimension à plusieurs dimensions

<?php
$arr = [5, 2, 8, 3, 1];
sort($arr);
print_r($arr); // 输出：[1, 2, 3, 5, 8]
?>

<?php
$students = [
    ['name' => 'Alice', 'score' => 90],
    ['name' => 'Bob', 'score' => 80],
    ['name' => 'Carol', 'score' => 70]
];
?>

<?php
usort($students, function($a, $b) {
    return $b['score'] <=> $a['score'];
});
print_r($students); // 输出：[
                        //     ['name' => 'Alice', 'score' => 90],
                        //     ['name' => 'Bob', 'score' => 80],
                        //     ['name' => 'Carol', 'score' => 70]
                        // ]
?>

<?php
$classes = [
    [
        ['name' => 'Alice', 'grade' => 'A'],
        ['name' => 'Bob', 'grade' => 'B'],
        ['name' => 'Carol', 'grade' => 'C']
    ],
    [
        ['name' => 'Dave', 'grade' => 'A'],
        ['name' => 'Eve', 'grade' => 'B'],
        ['name' => 'Frank', 'grade' => 'C']
    ],
    [
        ['name' => 'George', 'grade' => 'A'],
        ['name' => 'Helen', 'grade' => 'B'],
        ['name' => 'Ian', 'grade' => 'C']
    ]
];
?>

<?php
usort($classes, function($a, $b) {
    usort($a, function($c, $d) {
        return $d['grade'] <=> $c['grade'];
    });
    usort($b, function($c, $d) {
        return $d['grade'] <=> $c['grade'];
    });
    return $b[0]['grade'] <=> $a[0]['grade'];
});
print_r($classes); // 输出：[
                        //     [
                        //         ['name' => 'Alice', 'grade' => 'A'],
                        //         ['name' => 'Bob', 'grade' => 'B'],
                        //         ['name' => 'Carol', 'grade' => 'C']
                        //     ],
                        //     [
                        //         ['name' => 'Dave', 'grade' => 'A'],
                        //         ['name' => 'Eve', 'grade' => 'B'],
                        //         ['name' => 'Frank', 'grade' => 'C']
                        //     ],
                        //     [
                        //         ['name' => 'George', 'grade' => 'A'],
                        //         ['name' => 'Helen', 'grade' => 'B'],
                        //         ['name' => 'Ian', 'grade' => 'C']
                        //     ]
                        // ]
?>