php问题$market

//$shop_price = !empty($_POST['shop_price']) ? $_POST['shop_price']*0.9 : 0; //$market_price = !empty($_POST['market_price']) ? $_POST['market_price'] : round($shop_price*$GLOBALS['_CFG']['market_price_rate']); $zmm_tejia = explode(' ', $_

//$shop_price = !empty($_POST['shop_price']) ? $_POST['shop_price']*0.9 : 0;
//$market_price = !empty($_POST['market_price']) ? $_POST['market_price'] : round($shop_price*$GLOBALS['_CFG']['market_price_rate']);

$zmm_tejia = explode(' ', $_POST[cn_goods_name]);

这些函数是什么意思？特别是$market_price = !empty($_POST['market_price']) ? $_POST['market_price'] : round($shop_price*$GLOBALS['_CFG']['market_price_rate']);