php compare 2 array and manipulation increase value -

i have 2 array

a=array(a=>1,b=>2,c=>2,d=>2,e=>2,f=>2) 

and

b=array(a,b,d) 

i want make function compare_plus(array a, array b) if array have key== array b val in increase value of array @ key 1.

example above array , b:

c=compare_plus(a,b) =>> c=(a=>2,b=>3,c=>2,d=>3,f=>2) 

$a = array('a' => 1, 'b' => 2, 'c' => 2, 'd' => 2, 'e' => 2, 'f' => 2); $b = array('a', 'b', 'd');  $c = compare_plus($a, $b); print_r($c);  function compare_plus($arr, $plusarr){     foreach($plusarr $key)         $arr[$key]++;     return $arr; } 

codepad demo