Python 在字典中保持值的运行总数

我想让用户从商店里挑选一件商品，我想使用一个循环来跟踪价格（字典中的值），在用户每次输入后进行相加并保持一个运行总数。如果用户输入的内容不在字典中，则应表示该内容不存在。 提前谢谢你的帮助

def main():
    machine= {"1.shirt: $":10, "2.pants: $":15, "3.sweater: $":20,"4.socks: $":5, "5.hat: $":7}


    for key, value in machine.items():
       print(key,value)
       print("------------------------------")
       selection = input("Please choose the number of the item you would like to purchase: ")

    total=0
    for i in machine:
       if selection=="1":
           print("You chose shirt and your total is: $", machine["1.shirt: $"])
       elif selection=="2":
           print("You chose shirt and your total is: $", machine["2.pants: $"])
       elif selection=="3":
           print("You chose shirt and your total is: $", machine["3.sweater: $"])
       elif selection=="4":
           print("You chose shirt and your total is: $", machine["4.socks: $"])
       elif selection=="5":
           print("You chose shirt and your total is: $", machine["5.hat: $"])
      else:
           print("Your option does not exist. Your total is: ",total)

---

每次做出选择时，您都应该更新total的值。见下面的例子

def main():
    machine= {"1.shirt: $":10, "2.pants: $":15, "3.sweater: $":20,"4.socks: $":5, "5.hat: $":7}
    total=0
    for key, value in machine.items():
       print(key,value)
       print("------------------------------")
    while True: # Keep Looping
       selection = input("Please choose the number of the item you would like to purchase: ")

       if selection=="1":
           total += machine["1.shirt: $"];
           print("You chose shirt and your total is: $", total)
       elif selection=="2":
           total += machine["2.pants: $"];
           print("You chose shirt and your total is: $", total)
       else:
           print("Your option does not exist. Your total is: ",total)
           break