s[i:j] slice of s from i to j (3), (4) (3) If i or j is negative, the index is relative to the end of the string: len(s) + i or len(s) + j is substituted. But note that -0 is still 0.
(4) The slice of s from i to j is defined as the sequence of items with index k such that i <= k < j. If i or j is greater than len(s), use len(s). If i is omitted or None, use 0. If j is omitted or None, use len(s). If i is greater than or equal to j, the slice is empty. i can't follow (3) very well. for example:k = [1,2,3,4,5] k[-1:2]=[] k[-5:2]=[1,2] but k[-6:2] = [1,2] why k[-6:2] is [1,2]not [].i do follow (3),to make i positive by plusing len(k) twice.But the result is not what i expect.why,or did i misunderstand the rule of (3). -- http://mail.python.org/mailman/listinfo/python-list
