On Wed, 24 Oct 2007 16:28:20 -0700, [EMAIL PROTECTED] wrote: > On Oct 24, 5:44 pm, Michal Bozon <[EMAIL PROTECTED]> wrote: >> many Python newcomers are confused why range(10), does not include 10. > > How can they be confused?
Because in common English, counting starts at 1 and ranges normally include both end points (that is, it is a "closed" interval). If you say "I'll be away from the 4th to the 7th" and then turn up on the 7th, nearly everyone will wonder why you're back a day early. > Does base 10 have a digit ten? > Does base 2 have a digit two? > Does base 16 have a digit sixteen? > > Haven't you stopped counting on your fingers when you leave grade > school? range(N) is not designed to return the digits used in base N strings, and any connection is weak (what base does range(3, 25, 4) correspond to?). What little correspondence there is is an accidental coincidence of how we write numbers, not a fundamental fact about half-open intervals like range(). Having said that, and regardless of common English usage, using half-open intervals almost always leads to simpler programming and fewer errors. Creating syntax support for beginners to make extra off-by-one bugs is a terrible idea, no matter how seductive it seems for newbies. I know Ruby has (to my mind confusing!) support for both closed and half-open intervals, but I wonder how useful it is in practice? Ruby expression => Python equivalent 1..5 => range(1, 6) 1...5 => range(1, 5) -- Steven. -- http://mail.python.org/mailman/listinfo/python-list
