php update value of array with same key -

how can update same array key new value

array ( [key1] => 3 [key2] => 2 [key3] => 1  [key4] => 2)   array ( [key3] => 6 )  

expected answer:

array ( [key1] => 3 [key2] => 2 [key3] => 6  [key4] => 2) 

try one,

$first_array = array('key1' => 3,'key2' => 2,'key3' => 1,'key4' => 2); $second_array = array('key3' => 6); foreach ($first_array $key => $value) {     if(isset($second_array[$key])) {         $first_array[$key] = $second_array[$key];     } } var_dump($first_array);