fix

app/index/controller/Cart.php

@@ -172,7 +172,7 @@ class Cart extends Controller
         $list = $service->getList();
         $sum = '0.00';
         foreach ($list as $item) {
-            $temp = bcmul($item['goods_num'], $item['goods']['goods_price_min'], 2);
+            $temp = bcmul(strval($item['goods_num']), strval($item['goods']['goods_price_min']), 2);
             $sum = bcadd($sum, $temp, 2);
         }
         return $sum;