How does parenthesis change whether or not the output will be true or false?

Question

The question was this in my python beginners course Add a pair of parentheses to each expression so that it evaluates to True. 0 == 1 == 2

And the answer given was ( 0 == (1==2)) Isnt it still false in the answer too as 1 is not equals to 2 and 0 is not equal to any of them

`0 == False` See https://stackoverflow.com/questions/28033852/strict-comparison — Nick, May 03 '21 at 06:16
`(0 == (1==2))` evaluates to `(0 == False)`, which in Python is True. — trincot, May 03 '21 at 06:17
Also: https://stackoverflow.com/questions/2764017/is-false-0-and-true-1-an-implementation-detail-or-is-it-guaranteed-by-the. I don't have the final hammer for this tag :/ — trincot, May 03 '21 at 06:18
@trincot Thanks for digging that up; added as the primary dupe. — tripleee, May 03 '21 at 07:58

score 5 · Answer 1 · answered May 03 '21 at 06:17

0 == 1 == 2

This is a chained comparison, equivalent to

0 == 1 and 1 == 2

Neither statement is true, so the whole thing is false. This is the behavior you're imagining.

0 == (1 == 2)

This is not a chained comparison. This is a comparison of a number (zero) against a Boolean (1 == 2). We know 1 == 2 is false, so this is equivalent to

0 == False

And, in Python, 0 and False are (mostly) synonymous, and crucially they compare equal.

True

How does parenthesis change whether or not the output will be true or false?

1 Answers1