Recognizing when to use the modulus operator

Question

I know the modulus (%) operator calculates the remainder of a division. How can I identify a situation where I would need to use the modulus operator?

I know I can u

Answer 1

Often, in a loop, you want to do something every k'th iteration, where k is 0 < k < n, assuming 0 is the start index and n is the length of the loop.

So, you'd do something like:

int k = 5;
int n = 50;
for(int i = 0;i < n;++i)
{
    if(i % k == 0)  // true at 0, 5, 10, 15..
    {
        // do something
    }
}

Or, you want to keep something whitin a certain bound. Remember, when you take an arbitrary number mod something, it must produce a value between 0 and that number - 1.