Python — Why is there a difference between `0–3//2` and ` — 3//2`?

How to do floor/ceiling operations without the math module

Python uses the symbol - as both a unary (-x) and a binary (x-y) operator. These have different operator precedence.

In specific, the ordering wrt // is:

• unary -
• binary //
• binary -

By introducing a 0 as 0--3//2, the first - is a binary - and is applied last. Without a leading 0 as --3//2, both …