php - How to check if an associative array has an empty or null value -

in following associative array

$array = array(     [0] => 0     [1] => 1     [2] =>      [3] => 2     [4] =>  ) 

how can determine if given key has empty (or null) value? used

if(empty($array[$value]))  

and

if(isset($array[$value])) && $array[$value] !=='') 

when using empty false first array value 0 , isset doesn't seem trick.

use array_key_exists() , is_null() that. return true if key exists , has value far null

difference:

$arr = array('a' => null);  var_dump(array_key_exists('a', $arr)); // -->  true var_dump(isset($arr['a'])); // -->  false 

so should check:

if(array_key_exists($key, $array) && is_null($array[$key])) {     echo "key exists value of null"; }