Difference of operator precedence between C and Python

Question

Hi, everyone who loves both C and Python, did you ever notice the differences of operator precedence between C and Python?

If you know one that matters much when coding Python for a C programmer, please post below this thread. I notice some intricate differences on the following.

In Python, the so-called relationship operators such as “>,<,==,!= ” have the same precedence, while in C the precedence of “<,>” have higher precedence than that of “==,!=”.

Additionally, in Python, the so-called comparison operator such as the relationship operator can be chained. For example, the following expression

1 >2 == 0

evaluates to true In C, while False In Python.

In Python:
https://code.sololearn.com/c7GBcv4F8DIi/?ref=app

In C：
https://code.sololearn.com/c53o7u0EodU4/?ref=app

Answer 1

Ipang, both are wrong. Like slowweb and HonFu explained, we call it chaining of comparison operators. In mathematics, when we say 2>1>0, we mean "2>1 and 1>0". Same happens here in Python. So

4>2==0
(4>2) and (2==0)
True and False
False
https://docs.python.org/3/reference/expressions.html#comparisons

Answer 2

Thank you Kishalaya Saha 👍

I'm much accustomed to C/C++ explicit way for expression evaluation, and forgotten that chained operator from Python. It is one that confuses many Python learners when they try C/C++.

Answer 3

Without this thread, I may never thought about 3>2==1 😂

Answer 4

1 < 2 == 0 evaluates to False in both C and Python.

However, 4 > 2 == 2 evaluates to True in Python, but False in C.

Answer 5

In Python 4 > 2 == 0 translates to 4 > 2 and 2 == 0.

Answer 6

Ipang you're so welcome! It is indeed confusing, especially when used with the == operator (to me at least).

Answer 7

Diego
How 4 > 2 == 0 is evaluated in C and Python?

Answer 8

4>2 == 0 is evaluated as “ (4>2) and (2==0) ”in Python, while as “(4>2) == 0”in C. The Python case involves chained operator.

Answer 9

(4 > 2) == 0
(True) == 0
True == 0 ==> False ???

4 > (2 == 0)
4 > (False)
4 > False (0) ==> True ???

Which one is right? or both is wrong?

Answer 10

slowweb
Please reconsider one of the other responses for best answer mark, I came here only to seek for clarity, and found one, so my question of doubt shouldn't count for answer ✌

Answer 11

sorry, I have make a typos, the example should involve “1>2==0”

Answer 12

It seems in Python the quality operator “==” could be used for any two objects, regardless of object type. For example, the following codes are valid in Python:

print('aaaa' == 3)

Answer 13

你是中国人吗？