Python Foundation - part two

Some differences between python2.7 and python3

print is a function now in python 3

do print(a) and print a not work

division by int can return float

>>> 5/2 (python2.7)
2

while in python3

>>> 5/2
2.5

Some well-known APIs no longer return lists

dict.iterkeys(), dict.iteritems() and dict.itervalues() are no longer supported in python3
xrange is replaced by range
zip() now returns an iterator.

>>> iter = zip([1, 2, 3], ['a', 'b', 'c'])
>>> next(iter)
(1, 'a')
>>> next(iter)
(2, 'b')
>>> next(iter)
(3, 'c')
>>> next(iter)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
StopIteration

map() and filter() return iterator too, but we can use list(map()) to transform it.

Ordering function

All the elements to be sorted now must be comparable to each other
cmp argument providing a comparison function is no longer supported

All strings are now Unicode by default

raw_input() is abandoned and use input() instead