On Sun, Dec 15, 2013 at 11:54 AM, Rafael Knuth <rafael.kn...@gmail.com>wrote:
> Hej, > > I stumbled upon this program here (Python 3.3.0) and I don't quite > understand how the for loop plays with the return True statement: > > def is_prime(number): > for element in range(2, number): > if number % element == 0: > return False > return True > > Now, I would expect the following in case I call the function with the > variable 3: > > number = 3 > for element in range(2, 3): > 3 % 2 != 0: > Loop ends and program returns True. > > Let's do the same with the variable 9: > > number = 9 > for element in range(2,9): > 3 % 2 != 0: > My assumption is that the program should end the loop after the first > iteration again and it then should return True. > 3 % 2 isn't 0, so it increments element to 4. $ % 2 is 0 so it returns false The loop goes thru each number until it finds a factor ( == 0 is true). If it doesn't find a factor of the number after checking all numbers up to the number, it continues to the return true statement > > But instead, the program returns False (correctly for obvious reasons > because 9 is not a prime number). Can anyone help me understand what > error in reasoning I am making here? > > Thanks! > > All the best, > > Raf > _______________________________________________ > Tutor maillist - Tutor@python.org > To unsubscribe or change subscription options: > https://mail.python.org/mailman/listinfo/tutor > -- Joel Goldstick http://joelgoldstick.com
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