Or statements in python do not seem to work as in other languages since:
-1 < 0 | 0<0
returns False (should return true since -1<0 is True)
What is the problem?
2 Answers
There are two problems: First, the precedence of the operators is not what you expect. You can always add parens to make it explicit:
>>> (-1 < 0) | (0 < 0)
True
Also, single-pipe is a logical or that evaluates both of its arguments all the time. The equivalent of other languages's pipe-pipe is or:
>>> -1 < 0 or 0 < 0
True
2 Comments
Ned Batchelder
My 2.6.6 Python prompt printed "True"
moinudin
My bad, I typo'd and had
(-1 < 0) | (0 | 0)| has precedence over < (see the Python operator precedence table). Use parenthesis to force the desired order of operation:
>>> -1 < 0 | 0 < 0
False
>>> -1 < (0 | 0) < 0
False
>>> (-1 < 0) | (0 < 0)
True
You might prefer to use the boolean or operator (equivalent to || in many other languages) instead of the bitwise |, which will give you the desired precedence without parenthesis:
>>> -1 < 0 or 0 < 0
True
As a side note, -1 < 0 < 0 (or a < b < c) does the intuitive thing in Python. It is equivalent to a < b and b < c. Most other languages will evaluate it as (a < b) < c, which is not typically what you'd expect.
|with||(used e.g. in C and Java). (Other languages will evaluate the expression differently to Python though, but that is unrelated to the bitwise or operator, and instead to the way Python has special treatment for statement such asx < y < zwhich is missing from other languages.)