我怎樣才能讓這個方法更新每次通話

Question

class Store(object): 
    def __init__(self) : 
     self.total_cost=0 
     self.goods={} 
    def add_goods(self,goods_name,quantity,cost) : 
     cost=cost*quantity 
     self.total_cost=self.total_cost+cost 
     self.goods[goods_name]=quantity 
Q_store=Store() 
Q_store.add_goods('shirt',5,10) 
print (Q_store.goods) 
print (Q_store.total_goods) 
# it resulted to {'shirt':5} 
# total_goods= 50 
Q_store.add_goods('shirt', 5,10) 
print (Q_store.goods) 
# it's quantity remains 5 
# the answer remains 5 

在重新調用方法和印刷數量，其數量仍然是5，而不是10 我怎樣才能使該方法保持在每個呼叫調整量？因爲它似乎數量保持不變。先謝謝你。

Answer 1

給你：

class Store(object): 
    def __init__(self) : 
     self.total_cost=0 
     self.goods={} 
     self.total_goods =() 
    def add_goods(self,goods_name,quantity,cost) : 
     cost*=quantity 
     self.total_cost+=cost 
     if goods_name in self.goods: 
      self.goods[goods_name]+=quantity 
     else: 
      self.goods[goods_name]=quantity 

Q_store=Store() 
Q_store.add_goods('shirt',5,10) 
print (Q_store.goods) 
print (Q_store.total_cost) 
Q_store.add_goods('shirt', 5,10) 
print (Q_store.goods) 
print (Q_store.total_cost) 

我改變你的代碼的工作之一。你錯過的是+ =商品詞典。