Thanks. Note that $window_size of 0 will probably behave the same as $window_size of 1, though.

Update: Sorry, wrong. I misunderstood your examples. /..{0,-1}/ matches any two characters followed by the literal string "{0,-1}". This could still be a problem for certain input values, but such seem pretty unlikely. So you might want some special code for the boundary case, depending on how varied your inputs might be.

        - tye (but my friends call me "Tye")