I'm looking at the `setXPos()` method I have in my NPC class. My current error check checks if the value being passed is below zero, then if so, sets the value to zero. However, when I pass the value using the `walk()` function for the first time, no matter what direction is specified, it will be zero. So if I do a `walk("right")` call twice in the NPCMain class, I'll be at position 1.0 instead of 2.0. (The same of course applies to the `setYPos()` method).

Is this expected behavior? I didn't want to make an assumption since we're setting the default to -999.0 instead of just 0.0.

Good points all.  An easy way to handle this is as what was suggested.   Once the walk function has been called for the first time, you can set both x and y to be 0 and then proceed from there.  You could also have some logic that requires the user to set x and y to a positive position before allowing the walk function to work.  I am interested to see how people resolve this issue.