python - IF statement (checking for a string in a list) behave weirdly

Question

This will probably be a dumb question, but why does this piece of code behave like this?

>>> test = ['aaa','bbb','ccc']
>>> if 'ddd' or 'eee' in test:
...     print True
... 
True
>>>

I was expecting nothing printed on the stdio, because none of the strings in the IF statement are in the list.

Am I missing something?

score 7 · Accepted Answer

if 'ddd' or 'eee' in test

被评估为：

if ('ddd') or ('eee' in test)：

由于非空字符串始终为True，因此or操作短路并返回True。

>>> bool('ddd')
True

要解决这个问题，您可以使用：

if 'ddd' in test or 'eee' in test:

或any：

if any(x in test for x in ('ddd', 'eee'))：

score 4 · Accepted Answer

你的测试应该是

if 'ddd' in test or 'eee' in test:

在您当前拥有的代码中，“ddd”字符串被评估为布尔值，因为它不是空的，所以它的布尔值为 True

score 0 · Accepted Answer

>>> if 'ddd'
...     print True

will print

True

So you should write :

>>> if 'ddd' in test or 'eee' in test:
...     print True

in order to get the result you want.

score 0 · Accepted Answer

你在这里遗漏了一些东西：

if 'ddd' or 'eee' in test:

相当于：

if ('ddd') or ('eee' in test):

因此，这将永远是 True，因为'ddd'它被认为是 True。

你要：

if any(i in test for i in ('ddd', 'eee')):

4 回答 4