CODEWITHSUNDEEP
mathluadivisioncoronasdk
Scott Phillips
Scott Phillips

Reputation: 123

In Lua, how can I tell if a number divides evenly into another number?

In Lua, how can I tell if a number divides evenly into another number? i.e with no remainder? I'm just looking for a boolean true or false.

12/6 = 2 (true)
18/6 = 3 (true)
20/6 = 3.(3) (false)

Upvotes: 10

Views: 17817

Answers (2)

Max E.
Max E.

Reputation: 1917

The problem with using the modulus operator is, it doesn't work correctly on negative numbers. If you're going to be using negative numbers, use math.fmod instead: 

maxtothemax@maxtothemax-mint ~ $ lua 
> return  -13%6
5
> return  13%6
1
> return math.fmod (-13, 6)
-1
> return math.fmod (13, 6)
1
>

Upvotes: 1

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726809

Compare the remainder of the division to zero, like this:

12 % 6 == 0

18 % 6 == 0

20 % 6 ~= 0

The modulus operator (%) returns the remainder of division. For 12 and 6 it is 0, but for 20 and 6 it is 2.

The formula it uses is: a % b == a - math.floor(a/b)*b

Upvotes: 21

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