How does python interpret "True != True != True"?

Asked Jul 11 '14 at 14:06

Active Jul 11 '14 at 14:06

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I played around with python by writing some nonsense code, and noticed a strange behavior with a line of code I wrote.

>>> True != True != True
False

I can't wrap my head around why this statement evaluates to False. At first glance I thought python would surround one of the True != True with parentheses and then evaluate the whole statement, just like 1 + 1 + 1 is equivalent with (1 + 1) + 1 or 1 + (1 + 1). I tried it in python command line:

>>> (True != True) != True
True
>>> True != (True != True)
True

But it seems python chooses another strategy to evaluate True != True != True, since the statements above both evaluates to True.

So the question is, how does python actually interpret True != True != True?

asked Jul 11 '14 at 14:06

oscfri

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That's operator chaining. The post I closed this as a dupe of explains this for a closely related issue. – Martijn Pieters Jul 11 '14 at 14:07
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It is interpreted as `True != True and True != True`. – Martijn Pieters Jul 11 '14 at 14:08
Thanks, now I know this strange behavior has a name, and is actually a feature. Easier to Google next time :) – oscfri Jul 11 '14 at 14:23

How does python interpret "True != True != True"?

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