多个foreach嵌套循环的有关问题

多个foreach嵌套循环的问题

$xml = simplexml_load_file($xml_uri);


$offer_url=array(

					"ItemCondition"					=>"Qualifiers->ItemCondition",

					"ItemSubcondition"				=>"Qualifiers->ItemSubcondition",

					"FulfillmentChannel"			=>"Qualifiers->FulfillmentChannel",

					"ShipsDomestically"				=>"Qualifiers->ShipsDomestically",

					"ShippingTime"					=>"Qualifiers->ShippingTime->Max",

					"SellerPositiveFeedbackRating"	=>"Qualifiers->SellerPositiveFeedbackRating",

					"NumberOfOfferListingsConsidered"=>"NumberOfOfferListingsConsidered",

					"SellerFeedbackCount"			=>"SellerFeedbackCount",

					"LandedPrice"					=>"Price->LandedPrice->Amount",

					"ListingPrice"					=>"Price->ListingPrice->Amount",

					"Shipping"						=>"Price->Shipping->Amount",

					"MultipleOffersAtLowestPrice"	=>"MultipleOffersAtLowestPrice"


);


foreach($xml->GetLowestOfferListingsForASINResult->Product->LowestOfferListings->LowestOfferListing as $key)

{

foreach($offer_url as $name=>$value)

{

echo  $name."->".$key->$value."--------";


}

echo "<br>";

}

  } 

    ?>

$key->$value没有结果，请问应该怎么写？？
------解决思路----------------------
echo eval("return \$key->$value;");