How to access others variable inside of array_walk?

Question

I have a variable $id = 10, it's need to use inside of array_walk(). Like bellow :

$id = 10;
array_walk($profile_items, function(&$a) {
    $count = $this->db->where('profile_item_id', $a['id'])->where('cover_type_id', $id)->count_all_results('cover_type_profile_items_link');
    $a['selected'] = $id;
});
echo "<pre>";
print_r($profile_items).exit;

When i used $id variable inside of array_walk() it's show a error.

Message: Undefined variable: id

Any solution?

Thanks for Advice

Answer 1

You can use use keyword:

array_walk($profile_items, function(&$a) use($id) {

so,

$id = 10;
array_walk($profile_items, function(&$a) use($id) {
    $count = $this->db->where('profile_item_id', $a['id'])->where('cover_type_id', $id)->count_all_results('cover_type_profile_items_link');
    $a['selected'] = $id;
});
echo "<pre>";
print_r($profile_items);

---

To inherit by reference, add ampersand:

array_walk($profile_items, function(&$a) use(&$id) {

Answer 2

    $sample = [
        ['id'=>2, 'name' => 'one'],
        ['id'=>3, 'name' => 'two'],
    ];
    $id = 2;
    function test_alter(&$item1, $key, $prefix)
    {   
    if($item1['id'] == $prefix){
        $item1['name'] =  $item1['name']." modified";
        }            
    }
    array_walk($sample, 'test_alter', $id);
    echo "<pre>";
    print_r($sample);

Output

Array(
    [0] => Array
        (
            [id] => 2
            [name] => one modified
        )
    [1] => Array
        (
            [id] => 3
            [name] => two
        )
)