Modulus operator Substitute for c#

Questions & Answers
1

I need to have a number be divisible by certain amounts and the remainders would then by posted and I’m programming in Unity’s C# but I need a replacement since the modulus operator doesn’t seem to function on it.

5

Just been stung by this and I couldn’t see a recent thread with a definitive answer.

Some languages, including Python, return the mathematical mod from %.
In C# it’s rem not mod. They behave differently with negative numbers.

int rem = -8 % 32;
Debug.Log(System.String.Format("-8 % 32 = {0}", rem));

Yields:

-8 % 32 = -8

This is an important difference when wrapping array indices.
The mathematical mod is 24, not -8 and can be calculated (somewhat inconveniently) as follows:

int Mod(int a, int b)
{
    return (a % b + b) % b;
}

Hope this helps someone else. I’m new to C# so if there’s a better way please post it.

2

O_o What? No, mod totally works.

using UnityEngine;
using System.Collections;
using System;

public class Blah : MonoBehaviour {
	void Start () {
		var x = 123213213;
		var factor = 10;
		var divs = x / factor;
		var remainder = x % factor;
		Debug.Log(String.Format("{0} / {1} = {2} // {0} % {1} = {3}", x, factor, divs, remainder));
	}
}

Yields:

123213213 / 10 = 12321321 // 123213213 % 10 = 3
UnityEngine.Debug:Log(Object)
Blah:Start() (at Assets/Blah.cs:11)

It wont work on floats though; maybe you need to run “((int) myVector[2]) % 5” or something.

3

The modulus function works just fine in C#, not to mention Unityscript and Boo.

4

Try Mathf.Repeat

7

For those who are more curious, this article examines the fastest way to get the remainder between using modulus or alternative methods such as algebraic equations:

It’s obviously more for speed and micro-optimization junkies, but you’ll see several different faster ways than the straight modulus operation.

6

This is an old thread, but I felt compelled to write something for anybody who needs the answer to be explained and a quick example.

Short answer: Convert the int’s to var. Mod will then work.

// Wont work

int index = 3;

if(index % 2 == 0) {
}

//Will work

var indexVar = index;

var factor = 2;

if(index % factor == 0) {
}