I discovered this when my students were creating a fraction class. 7/4 = 1 however -7/4 = -2 It seems to me the second result should be -1 It appears it is using the floor function but it isn't what my students wanted nor can I think of when anyone would want this result. Anyone know why? Thanks for any help Terry S - tscott@fisher.unco.edu
Yeah this is one of the big stumbling blocks for novices. What you're seeing is a side-effect of C's int division. 7/4 is 1.75, but 1.75 is a float, not an int. ints can only be whole numbers.
Fortunately, the developers of python recognized this problem, but they couldn't simply change it right away because it might break existing python programs. So, to enable "real-world" division where 7/4 = 1.75, add this line to the top of your python script and everything will magically work:
from __future__ import division
See also this for more info about this and other stumbling blocks: http://developers.coedit.net/BeginnerErrorsWithPythonProgramming