Array
    (
        [0] => 1
        [1] => 2
        [2] => 3
        [3] => 4
        [4] => 5
        [5] => 6
        [6] => 7
        [7] => 8
    )

    Array
    (
        [0] => 6
        [1] => 8
        [2] => 10
        [3] => 12
    )

/**
* return the joined arrays.
*
* @exception   Throws an exception if the two arrays are not of equal size.
* @param       Array $a the first array to be joined.
* @param       Array $b the second array to be joined.
* @return      Array the joined arrays.
*/
function joinArrays(Array $a, Array $b)
{
   if(count($a) == count($b)){
      $c = Array();
      for($i=0;$i<count($a);$i++){
          $c[$i] = $a[$i] + $b[$i];
      }
   }else{
      Throw new Exception("Exception: Arrays are not of equal size."); 
   }
   return $c;
}