PHP error. Why is "variable undefined" inside array_map?

Question

I am using array_map function in my php application. I defined the array_map function like this.

$ratingID =  $this->db->insert_id();      $rated_item_array = array_map(function ($a) {         return $a + array('RatingID' => $ratingID);     }, $rated_item_array);   

Php notice comes

A PHP Error was encountered  Severity: Notice  Message: Undefined variable: ratingID 

When i print the $ratingID . i prints the value correctly , so $ratingID is defined. Why it is undfined in array_map function? My $rated_item_array is

Array (     [0] => Array         (             [RatingFactorPreferenceID] => 1,             [PreferenceID] => 45,             [RatedValue] => 1,             [CreatedOn] => 1326790338,             [CreatedBy] => 25         )      [1] => Array         (             [RatingFactorPreferenceID] => 2,             [PreferenceID] => 45,             [RatedValue] => 1,             [CreatedOn] => 1326790338,             [CreatedBy] => 25         )      [2] => Array         (             [RatingFactorPreferenceID] => 3,             [PreferenceID] => 45,             [RatedValue] => 1,             [CreatedOn] => 1326790338,             [CreatedBy] => 25         ) ) 

Answer 1

$rated_item_array = array_map(   function ($a) use ($ratingID){      return $a + array('RatingID' => $ratingID );    },    $rated_item_array );