php如何改变二维数组的值

// 修改 二维数组中的 name为 Getchar
$users = array(
    array('name' => 'GetcharZp', 'age' => 19),
    array('name' => 'Mcx', 'age' => 18)
);
for ($i = 0; $i < count($users); ++ $i) {
    $users[$i][&#39;name&#39;] = &#39;Getchar&#39;;
}
print_r($users);

// 修改 二维数组中的 name为 Getchar
$users = array(
    array('name' => 'GetcharZp', 'age' => 19),
    array('name' => 'Mcx', 'age' => 18)
);
foreach ($users as &$user) {
    $user['name'] = 'Getchar';
}
unset($user); // 销毁掉 user 引用
print_r($users);