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- Subject: Re: Modulo with negative operands
- From: Dirk Laurie <dirk.laurie@...>
- Date: Mon, 22 Apr 2019 21:45:37 +0200
Op Ma. 22 Apr. 2019 om 14:11 het Albert Chan <email@example.com> geskryf:
> Does anyone write Lua code that uses % negative divisor behavior ?
> If we really need a minus sign, It seems better to explicitly say it.
The manual for Lua 5.3 says:
Floor division (//) is a division that rounds the quotient towards
minus infinity, that is, the floor of the division of its operands.
Modulo is defined as the remainder of a division that rounds the
quotient towards minus infinity (floor division).
I.e. % and // are locked together so that a == b*(a//b)+a%b
Previous versions of Lua did not have //, and the discussiion of % was
accordingly longer and may have been confusing to some readers.
It's quite simple now: the result of a%b always lies in the half-open
range from 0 to b, up or down, with b not included.