I am trying to make a 2d shooter. The idea is that it will be a sqaire map with ships that can fly about in any direction. What I can't work out is how to make them go in lots of different directons.

Code:
//up
ship.y-1
//up left
ship.y-1 ship.x-1
//left 
ship.x-1
...etc
doing this I can see how it would be possible to make ships go in 8 directions and I can see how it would be possible to make ships go in 16 directions but what would be a good way of making ships able to travel in all 360 degrees?