False或None与None或False [英] False or None vs. None or False

问题描述

In [20]: print None or False
-------> print(None or False)
False

In [21]: print False or None
-------> print(False or None)
None

这种行为使我感到困惑.有人可以向我解释为什么会这样吗?我希望他们的行为都一样.

This behaviour confuses me. Could someone explain to me why is this happening like this? I expected them to both behave the same.

推荐答案

如果x为true，则表达式x or y的值为x；如果x为false，则为y.

The expression x or y evaluates to x if x is true, or y if x is false.

请注意，以上句子中的"true"和"false"是指真实性"，而不是固定值True和False.如果是"true"，则使if语句成功.某些假"的东西会使它失败. "false"值包括False，None，0和[](空列表).

Note that "true" and "false" in the above sentence are talking about "truthiness", not the fixed values True and False. Something that is "true" makes an if statement succeed; something that's "false" makes it fail. "false" values include False, None, 0 and [] (an empty list).

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