Texom512 Texom512 - 7 days ago 5
Python Question

Why does "not(True) in [False, True]" return False?

If I do this:

>>> False in [False, True]
True


That returns
True
. Simply because
False
is in the list.

But if I do:

>>> not(True) in [False, True]
False


That returns
False
. Whereas
not(True)
is equal to
False
:

>>> not(True)
False


Why?

Answer

Operator precedence 2.x, 3.x. The precedence of not is lower than that of in. So it is equivalent to:

>>> not (True in [False, True])
False

This is what you want:

>>> (not True) in [False, True]
True

As @Ben points out: It's recommended to never write not(True), prefer not True. The former makes it look like a function call, while not is an operator, not a function.