Question

I use the following code to fill all empty keys in sub-arrays with ``:

$array = array(
        'note' => array('test', 'test1'),
        'year' => array('2011','2010', '2012'),
        'type' => array('conference', 'journal', 'conference'),
    );

foreach ($array['type'] as $k => $v) {
  foreach($array as $element => $a) {
    $iterator = $array[$element];
    if(!isset($iterator[$k])){       
       $iterator[$key] = '';
    }
  }
}

print_r($array);

The problem is that it is not actually changing the elements in $array but in temporary variable $iterator.

I know that this is a simple question but I would like to find out the best and fastest solution.

Answer 1

You don’t need the $iterator variable, you can do just:

foreach ($array['type'] as $k => $v) {
  foreach($array as $element => $a) {
    if(!isset($array[$element][$k])){       
       $array[$element][$key] = '';
    }
  }
}

I would also recommending switching the inner and outer loops, so it’s more readable and more efficient.

foreach($array as $element => $a) {
       foreach ($array['type'] as $k => $v) {
        if(!isset($array[$element][$k])){       
           $array[$element][$key] = '';
        }
      }
    }