FIFO queue use case

I have a simulation whose number of time steps varies according to inputs. To find the last state of the simulation via interpolation, I need to save the last N time steps. I can use a FIFO queue to save the results of last N time steps (e.g. to use in interpolation). Pseudocode:

step() {

    result = calcStateAtCurrentTime();

    queue.push(result);

    if(queue.size() > N) {

        queue.pop();

    }    

}

Bonus: To print unsigned int 64, use printf("%"PRId64", myUInt64)