Re: "undefined behavior"?

On 15/06/2024 05:45, DFS wrote:

On 6/14/2024 11:56 PM, Keith Thompson wrote:

DFS <nospam@dfs.com> writes:

On 6/14/2024 9:39 PM, Keith Thompson wrote:

DFS <nospam@dfs.com> writes:
[...]

During conversion, I got a Python error I don't remember seeing in the past:
>
"TypeError: list indices must be integers or slices, not float"
>
because division returns a float, and some of the array addressing was
like this: nums[i/2].

[...]
C's "/" operator yields a result with the type of the operands
(after
promotion to a common type).
Python's "/" operator yields a floating-point result.  For C-style
integer division, Python uses "//".  (Python 2 is more C-like.)

>
I was surprised python did that, since every division used in the
array addressing results in an integer.
>
After casting i to an int before any array addressing, // works.

>
I'm surprised you needed to convert i to an int.  I would think that

 > just replacing nums[i/2] by nums[i//2] would do the trick,
 > as long> as i always has an int value (note Python's dynamic typing).   If i

is acquiring a float value, that's probably a bug, given the name.

 I spotted the issue.  Just prior to using i for array addressing I said:
i = N/2.
 The fix is set i = int(N/2)
  

But if you want help with your Python code, comp.lang.python is the
place to ask.

 Thanks for your help, but David Brown is a Python developer and I'll ask him python questions here whenever I care to.

Yeah do that. Set up a private corner of comp.lang.c where David Brown has a sideline answering questions about Python from only one poster.
Nobody else is allowed to answer.
Sounds ridiculous, yes?

In the recent past you were involved in discussions on perl, Fortran and awk, among other off-topics.
 Rules for thee but not for me?