Python: assignment operator and double-equals in the same line

Question

Is this allowed syntax?

for bit in binary_string:
    is_zero = bit == '0'
    ...

Edit: ~~My IDE~~ Python in terminal is throwing syntax error. I found it here: https://github.com/johnmee/codility/blob/master/ex-1-1-binarygap.py#L33

edit:

>>> N = 1004
>>> binary_string = str(bin(N))[2:]
>>> for bit in binary_string:
...     is = bit == '0'
  File "<stdin>", line 2
    is = bit == '0'
     ^
SyntaxError: invalid syntax

sure it is. This assigns `is_zero` the value of the operation `bit=="0"`, so if `bit` was `"0"` before, `is_zero` is now `True`. This is perfectly valid python. What error is your IDE giving *exactly*? — Zinki, Apr 10 '18 at 06:31
There's nothing wrong in the syntax, is_zero gets populated based on whether bit is equal to zero or not. It should work. — Mehul Jain, Apr 10 '18 at 06:32
Check that you don't have an error further up your code, for example a missing single quote would detect an error on this line. Could you please show the exact error message? — cdarke, Apr 10 '18 at 06:34
See https://stackoverflow.com/questions/13650293/understanding-pythons-is-operator — cdarke, Apr 10 '18 at 06:36
I'm going to downvote your question because you first said you used `is_zero` and then you showed you used `is`, which is a python keyword. Inconsistency like that is not help to anyone trying to answer your question. — cdarke, Apr 10 '18 at 06:39
for future reference, it would be helpful if, when you have an error with your code, you actually posted the code that throws the error. The original sample you posted was perfectly fine and you failed to mention that you'd changed it to create the error you were seeing. Had you posted your actual code (with the `is`) originally, your question would have been solved in seconds. — Zinki, Apr 10 '18 at 06:39
If you feel like `is` the variable name better suits here, then use `is_` to avoid confict with python keywords. — Abdul Niyas P M, Apr 10 '18 at 06:40

score 2 · Accepted Answer · answered Apr 10 '18 at 06:36

2

It is allowed, your problem is, that is is a reserved keyword, e.g.

foo is None

Rename your variable ;)

answered Apr 10 '18 at 06:36

hellow

12,430
7
56
79

score 1 · Answer 2 · answered Apr 10 '18 at 06:37

Yes, it is legal because the right hand side of = is an expression which returns a value. In this case, the value True or False. After the expression has been evaluated, the name is_zero is assigned to that value.

Your SyntaxError is raised because you are trying to assign to the protected word is.

Python: assignment operator and double-equals in the same line

2 Answers2