list.remove(x)：x没有在列表中使用while循环

Question

场景

使用练习7-8中的列表sandwich_orders，确保三明治pastrami至少在列表中出现三次。在程序开始附近添加代码，打印一条消息，说明deli已经用完pastrami，然后使用while循环从sandwich_orders中删除所有出现的pastrami。确保没有pastrami三明治在finished_sandwiches结束。

代码我编写了：

sandwich_orders=['egg&mayo','cheese&onion','chicken&sweetcorn','pastrami','pastrami',
'egg&watercress','pastrami','pastrami']
finished_sandwiches=[ ]

current_sandwich=sandwich_orders.pop()

print(f"\nYour Sandwich has been prepared : {current_sandwich}")

while current_sandwich:

    print(f"\nCurrent sandwich is {current_sandwich}!!")

    if current_sandwich=='pastrami':
        sandwich_orders.remove('pastrami')
        print(f"\n{current_sandwich} has been removed from the orders")
    else:
        finished_sandwiches.append(current_sandwich)
        print(f"\nYour Sandwich has been prepared : {current_sandwich}")
print(f"\nList of finshed swandwiches : {finished_sandwiches}")

print(f"\nList of Sandwich Orders recieved : {sandwich_orders}")

下面的是执行代码后的错误

Traceback (most recent call last):
  File "C:\Users\thota01\AppData\Local\Programs\Python\Python38\Python_Input_whileLoops\movietickets.py", line 9, in <module>
    sandwich_orders.remove('pastrami')

**ValueError: list.remove(x): x not in list**

Answer 1

如果你已经打开了最后一个‘意大利面’三明治，它就不在名单上了，lst.pop

请注意，您没有更改current_sandwich anywere，所以它也是一个infinate循环

顺便说一句，while current_sandwich会让你得到异常，因为你会弹出一个空列表

sandwich_orders=['egg&mayo','cheese&onion','chicken&sweetcorn','pastrami','pastrami',
'egg&watercress','pastrami','pastrami']
finished_sandwiches=[ ]

print(f"\nYour Sandwich has been prepared : {current_sandwich}")
while sandwich_orders:
    current_sandwich = sandwich_orders.pop()
    print(f"\nCurrent sandwich is {current_sandwich}!!")
    if current_sandwich=='pastrami':
        print(f"\n{current_sandwich} has been removed from the orders")
    else:
        finished_sandwiches.append(current_sandwich)
        print(f"\nYour Sandwich has been prepared : {current_sandwich}")
print(f"\nList of finshed swandwiches : {finished_sandwiches}")

print(f"\nList of Sandwich Orders recieved : {sandwich_orders}")