php循环foreach

<?php
// 索引数组
$numbers = [1, 2, 3, 4, 5];

// 遍历值
foreach ($numbers as $number) {
    echo $number . "\n";
}

// 关联数组
$students = [
    'Alice' => 20,
    'Bob' => 22,
    'Charlie' => 21
];

// 遍历键和值
foreach ($students as $name => $age) {
    echo "$name is $age years old.\n";
}
?>

<?php
$array = [1, 2, 3, 4, 5];

foreach ($array as $key => $value) {
    $temp = $value * 2;
    $array[$key] = $temp;
}

print_r($array);
?>

<?php
$array = [1, 2, 3, 4, 5];

foreach ($array as &$value) {
    $value *= 2;
}

print_r($array);
?>