php - SimpleXMLElement Object and hidden child elements -

i'm asking explanation of following behavior behind scene in php.

i have simplexmlelement object print_r(); here result:

array (     [shipments] => simplexmlelement object         (             [shipment] => simplexmlelement object                 (                     [rates] => simplexmlelement object                         (                             [rate] => simplexmlelement object                                 (                                     [service] => c                                     [servicecharge] => 10.18                                     [servicechargedetails] => simplexmlelement object                                         (                                             [basecharge] => 8.33                                             [codcharge] => 0                                             [declaredcharge] => 0                                             [additionalcharges] => 1.85                                             [saturdaycharge] => 0                                         )                                      [fuelcharge] => 0                                     [totalcharge] => 10.18                                     [billedweight] => 6                                     [transitdays] => 1                                     [expecteddeliverydate] => 20160121                                     [committime] => 17:00:00                                     [ratezone] => 2                                     [globalrate] => 10.66                                 )                          )                      [uid] => id1                     [delzip] => 95126                     [puzip] => 95035                     [declared] => 100                     [residential] => true                     [cod] => 0                     [saturdaydel] => false                     [weight] => 2                     [dim] => simplexmlelement object                         (                             [length] => 10                             [width] => 12                             [height] => 13                         )                      [error] => simplexmlelement object                         (                         )                  )              [error] => simplexmlelement object                 (                 )          )  ) 

please take @ "totalcharge". doesn't seem have child elements when following:

print_r($response['shipments']->shipment->rates->rate->totalcharge); 

here get:

simplexmlelement object (     [0] => 10.18 ) 

i'm trying understand how did [0] there , why initial print_r didn't show it?

thanks!