回顾
index()
的索引值超出范围时会抛出异常
>>> [0, 1, 2, 3, 4].index(6)
Traceback (most recent call last):
File "<pyshell#0>", line 1, in <module>
[0, 1, 2, 3, 4].index(6)
ValueError: 6 is not in list
>>>
in
in
与index()
搭配可以防止上述的异常
>>> a = [0, 1, 2, 3, 4]
>>> if 6 in a:
print(a.index(6))
else:
print("not found")
not found
>>>
not in
>>> 6 not in [0, 1, 2, 3, 4]
True
>>>
补充
in
,not in
只能判断一层关系
>>> 3 in [0, 1, 2, [3, 4, 5]]
False
>>>
- 两层的解决办法
>>> for e in a:
if type(e) is list:
print(3 in e)
elif e == 3:
print(True)
True
>>>