I want to know which determines the output like not in this case applies to first condition only or both

Question

x=(not (5==5) and (10<12))
print(x)

when executing. not negates the first expression or both?

In my opinion "not" should be executed with (5==5) only but my colleague says it will affect the whole expression in the bracket like (5==5) and (10<12).

Answer 1

You can follow the approach I use. Instead of and we can place or operation to verify the answer. The result shows True . As the result is true so we can say that not (5==5) applies first. If the not operation runs with ((5==5) or (10<12)) then final result should be False. Hope it will help to understand.

Answer 2

It all comes down to Operator precedence. Looking at the table, not is higher than and so it goes first. So you are right, the not goes with the (5==5).

You can test with a simpler example.

>>> not 1 and 2
False

Python calculated not 1 and since it's False, it short-circuited the and operation.

>>> not 0 and 2
2

Python calculated not 0 and since it is True, continued through the and.

>>> not (0 and 2)
True

Your colleague's prediction was wrong.

>>> (not 0) and 2
2

Your prediction worked!