遍历多个php数组以更改值

Question

I have an array $users as such:

  [0] => Array (
    [userid] => 1
    [score] => 9.9
  )
  [1] => Array (
    [userid] => 2
    [score] => 9
  )

For each user, I then retrieve items and store them into an array, $results :

foreach ($users as $user) {
  $items = getItems($user['userid']);
  $results[] = $items:
}

The $results array ends up looking like this:

[0] => Array (
  [0] => Array (
    [itemid] => 1
    [rating] => 9.9
  )
  [1] => Array (
    [itemid] => 2
    [rating] => 9
  )
)
[1] => Array (
  [0] => Array (
    [itemid] => 3
    [rating] => 8.5
  )
  [1] => Array (
    [itemid] => 2
    [rating] => 7.5
  )
)

What I would like to do, is weigh the item rating with the user score. So, for each item, the rating would be multiplied by user score * 0.1.

What I've tried is this:

foreach ($users as $user) {
  $items = getItems($user['id']);
  foreach ($items as $item) {
    $item['rating'] = $item['rating'] * $user['score'] * 0.1;
  }
  $results[] = $items:
}

but to no avail. What am I doing wrong and how do I get the desired result?

Answer 1

By default in foreach the value is passed by value . So even if you change the data inside of an array inside the loop it will not be reflected. So you have to use & before $item to pass the array data by reference .

You can learn more about it here http://php.net/manual/en/control-structures.foreach.php