为什么要添加两个字符串而不是一个?

Question

这是我的源代码:

destinations={"",}
destinations.discard("")
flightterminals={"Terminal 1":[],"Terminal 2":[], "Terminal 3":[]}
proceed="yes"
count=0
flightnumber=int(input("How many flights do you want to add: "))
for i in range(flightnumber):
count+=1
print("Where is plane {} headed?".format(count))
temp=input("")+"1"
destinations.add(temp[:-1])
while ((temp in flightterminals["Terminal 1"]) or (temp in flightterminals["Terminal 2"]) or (temp in flightterminals["Terminal 3"])):
temp=temp[:-1]+str(int(temp[-1])+1)
print(type(temp))
print(temp)
flightterminals["Terminal {}".format((count-1)%3+1)]+=temp
print(flightterminals["Terminal 1"])

这里是终端:

Flight Terminal Manager 5600
How many flights do you want to add: 1
Where is plane 1 headed?
x
<class 'str'>
x1
['x', '1']

似乎倒数第三行flightterminals["Terminal {}".format((count-1)%3+1)]+=temp向我的字典中的集合添加了两个字符串，尽管temp在前一行中显示只是一个字符串。我做错了什么?

Answer 1

字典中的元素是列表。在您所谈论的线路中，您使用+=算子。因此，temp被认为是一个列表，它的元素被推到字典中相应列表的末尾。你必须使用append():flightterminals["Terminal {}".format((count-1)%3+1)].append(temp)