Mathematically, starting with zero is more consistent, because it leads to the fact that the length of a range is the difference between its bounds (length x..y

Mathematically, starting with zero is more consistent, because it leads to the fact that the length of a range is the difference between its bounds (length x..y == y-x). More elaborate and rigorous: http://www.cs.utexas.edu/~EWD/transcriptions/EWD08xx/EWD831.html http://www.cs.utexas.edu/~EWD/transcriptions/EWD08xx/EWD831....