XNA - gameTime modulo returns 0

Question

i = (gameTime.TotalGameTime.Milliseconds / n) % 11

the modulo here returns the following numbers: {1,2,3,4,5,6,7,8,9,10,0,1,0} But those last zeros and the one are bothering me because it shouldn't be like this, should it? My wanted result is returning {1,2,3,4,5,6,7,8,9,10,11,0}, but it doesn't. Has anyone an explanation for it? I have totally no idea what causes it, I've already tried different versions of this code, also changing the 11 to something else but it didn't work out too.

Answer 1

Your modulo value should be 12, not 11. Modulo returns the remainder of the division (More precisely the equation of m % n is m - floor(m/n)n), so 11 / 11 will indeed return 0.

However, with 12, 11 / 12 will be 11, 12 / 12 is 0 and 13 / 12 have 1 as the remainder. It 'wraps around' your value - 1

So you should use this instead :

i = (gameTime.TotalGameTime.Milliseconds / n) % 12

Examples with 12:

var b = 10 % 12; //10
var c = 11 % 12; //11
var d = 12 % 12; //0
var e = 13 % 12; //1

Answer 2

No, because 11 % 11 is zero. See documentation: http://msdn.microsoft.com/en-us/library/0w4e0fzs.aspx

Answer 3

No, the % operator returns the remainder when dividing the left operand by the right operand. In other words, x % x always returns 0 becuase x is perfectly divisible by x. Or to put it more generally, for integers, n, m and x, (n * x + m) % x == m

If you want values which range from 0 to 11, use modulo 12:

i = (gameTime.TotalGameTime.Milliseconds / n) % 12