Priority of operators: > and == [duplicate]
This has to do with operator chaining. Unlike C/C++ and most other languages, Python allows you to chain comparison operators just like you would in normal mathematics. From the documentation:
Comparisons can be chained arbitrarily, e.g.,
x < y <= zis equivalent tox < y and y <= z, except thatyis evaluated only once (but in both caseszis not evaluated at all whenx < yis found to be false).
So, this expression:
5 > 4 == 1is actually interpreted as:
5 > 4 and 4 == 1 # Except that 4 is only evaluated once.which becomes:
True and Falsewhich is False.
Using parenthesis however changes how Python interprets your comparison. This:
(5 > 4) == 1becomes:
True == 1which is True (see below for why). Same goes for:
5 > (4 == 1)which becomes:
5 > Falsewhich is also True.
Because of PEP 0285, bool was made a subclass of int and True == 1 while False == 0:
>>> issubclass(bool, int)True>>> True == 1True>>> False == 0True>>>