php数组元素排序

<?php
$numbers = array(3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5);
sort($numbers);
print_r($numbers);
?>

Array
(
    [0] => 1
    [1] => 1
    [2] => 2
    [3] => 3
    [4] => 3
    [5] => 4
    [6] => 5
    [7] => 5
    [8] => 5
    [9] => 6
    [10] => 9
)

<?php
$students = array(
    "John" => 85,
    "Mary" => 90,
    "Bob" => 78,
    "Alice" => 92
);
ksort($students);
print_r($students);
?>

Array
(
    [Alice] => 92
    [Bob] => 78
    [John] => 85
    [Mary] => 90
)

<?php
$fruits = array("apple", "banana", "cherry", "date");
usort($fruits, function($a, $b) {
    return strlen($b) - strlen($a);
});
print_r($fruits);
?>

Array
(
    [0] => banana
    [1] => cherry
    [2] => apple
    [3] => date
)

<?php
$fruits = array("apple" => 1, "banana" => 2, "cherry" => 3);
asort($fruits);
print_r($fruits);

// 保留原键
$sortedValues = array_values($fruits);
print_r($sortedValues);
?>

<?php
$numbers = array(3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5);
usort($numbers, function($a, $b) {
    return $b - $a; // 降序排列
});
print_r($numbers);
?>