Why avoid while loops?

Question

I\'m about 2 weeks deep in my study of Python as an introductory language. I\'ve hit a point in Zed\'s \"Learn Python the Hard Way\" where he suggests:

Answer 1

It's because in the typical situation where you want to iterate, python can handle it for you. For example:

>>> mylist = [1,2,3,4,5,6,7]
>>> for item in mylist:
...     print item
... 
1
2
3
4
5
6
7

Similar example with a dictionary:

>>> mydict = {1:'a', 2:'b', 3:'c', 4:'d'}
>>> for key in mydict:
...     print "%d->%s" % (key, mydict[key])
... 
1->a
2->b
3->c
4->d

Using a while loop just isn't necessary in a lot of common usage scenarios (and is not "pythonic").

---

Here's one comparison from a mailing list post that I though was a good illustration, too:

> 2. I know Perl is different, but there's just no equivalent of while
> ($line = ) { } ?

Python's 'for' loop has built-in knowledge about "iterable" objects, and that includes files. Try using:

for line in file:
    ...

which should do the trick.