Hanfei Sun - 4 months ago 13

Java Question

For example,

`(-3) % 2`

`-1`

`1`

What is the preferred way to get the positive remainder in Scala? Such as

`(((-3) % 2) + 2) % 2`

`abs(-3 % 2)`

Answer

In scala, why could remainder (%) operator return a negative number?

There are different conventions for the sign of the result of a modulo operation; Wikipedia has a good article on it. Scala, like most but by no means all programming languages, has the result take the sign of the dividend (the `-3`

in your case).

What is the preferred way to get the positive remainder in Scala?

I doubt there's a generally-agreed preferred way; if it were me, either use `Math.floorMod`

, which gives a result with the sign of the divisor (`2`

in your example) instead of the dividend (this doesn't just mean the same value as `%`

with a different sign, see the linked JavaDoc for details). Or just an `if`

afterward (`if (result < 0) { result += M; }`

[where `M`

is the divisor, `2`

in your example]).