Assign Value to STD class object array

Question

I need a little assistance with the STD class objects.

        $checking_w_products = explode("-",$orderline_val->products[$x]->sku);
        if(count($checking_w_products)>1)
        {
            if($checking_w_products[0]=="W")
            {

                $orderline_val->products[$x] = (object) array(
                    'sku '=>$checking_w_products[1]
                );

            }
            else
            {
                $orderline_val->products[$x] = (object) array(
                    'sku '=>'ahmad'
                );
            }
        }

        echo $orderline_val->products[$x]->sku;
        die;

I am trying to update the product sku but somehow it is not doing so..It just keeps the value of

 $orderline_val->products[$x]->sku 

as it is without updating it. I used [this]:How to set attributes for stdClass object at the time object creation example too but no effect...

If you can then please guide me how can I update the value of

$orderline_val->products[$x]->sku;

Thanks