Move one position forward and one position back

Question

Looking for a pair of words that compactly express the notion of moving one position forward, and one position backward.

I had thought to use "advance" for the first, as you might say a clock's second hand advances to the next position. But I'm having a hard time coming up with a corresponding word for the opposite direction. I had thought of regress, and recede and some others but they all seem to me to have a connotation of reverting to a previous state instead of simply moving in a rearward direction.

I think "recess" (as in astronomical "procession" / "recession") almost has the right flavor but that meaning of recess is not well known.

Context: This is for naming a pair of subroutines for navigating a list or array in a software system. One can advance one position in the array or <move backward> one position.

Answer 1

In programming, we used increment to add one count, decrement to subtract one count.

The process of increasing in number, size, quantity, or extent.

http://www.thefreedictionary.com/increment

Simpler, use step forward one or step back one, not fancy but clear.

Answer 2

You could say retreat. But that does sound sort of strange.

You could use "following"/"previous", "next"/"last" (last isnt so good). Or some combination.

Theres increment and decrement. That doesn't really work.

I don't know what the whole name is, but just making the name longer can make a weird word much more clear. "previousItem" or "getPreviousItem" and "getFollowingItem" or something maybe. to be very clear, you could say "incrementPosition" or even "incrementPositionInArray" (and decrement for the opposite direction).