>>> import math >>> def distance1(x1, y1, x2, y2): dx = x2 - x1 dy = y2 - y1 dsquared = dx**2 + dy**2 result = math.sqrt(dsquared) print result return result
>>> def distance2(x1, y1, x2, y2): dx = x2 - x1 dy = y2 - y1 dsquared = dx**2 + dy**2 result = math.sqrt(dsquared) print result They don't do the same thing here... >>> distance1(1,2,3,4) 2.82842712475 2.8284271247461903 >>> distance2(1,2,3,4) 2.82842712475 the 'return result' line passes the result object in the function back to where the function was called. Functions without a return statement default to returning 'None'. Calling the functions within a print statement illustrates the difference: >>> print distance1(1,2,3,4) 2.82842712475 2.82842712475 >>> print distance2(1,2,3,4) 2.82842712475 None >>> As you can see, distance2 does not actually return the result of the calculation to the interactive prompt... max -- http://mail.python.org/mailman/listinfo/python-list
