Reversing a string

[Scott]

Yeah I know strings == immutable, but question 1 in section 7.14 of "How to
think like a computer Scientist" has me trying to reverse one.

I've come up with two things, one works almost like it should except that
every traversal thru the string I've gotten it to repeat the "list" again.
This is what it looks like:

        
                        
                        
                >>>mylist = []
def rev(x):
 
 
 
 
for char in x:
mylist.append(char)
mylist.reverse()
print mylist
 

And the output that sorta works like it should, but threw a curveball, at me
looks like this:

>>rev("this is just a test")

['t']
['h', 't']
['i', 't', 'h']
['s', 'h', 't', 'i']
[' ', 'i', 't', 'h', 's']
['i', 's', 'h', 't', 'i', ' ']
['s', ' ', 'i', 't', 'h', 's', 'i']
[' ', 'i', 's', 'h', 't', 'i', ' ', 's']
['j', 's', ' ', 'i', 't', 'h', 's', 'i', ' ']
['u', ' ', 'i', 's', 'h', 't', 'i', ' ', 's', 'j']
['s', 'j', 's', ' ', 'i', 't', 'h', 's', 'i', ' ', 'u']
['t', 'u', ' ', 'i', 's', 'h', 't', 'i', ' ', 's', 'j', 's']
[' ', 's', 'j', 's', ' ', 'i', 't', 'h', 's', 'i', ' ', 'u', 't']
['a', 't', 'u', ' ', 'i', 's', 'h', 't', 'i', ' ', 's', 'j', 's', ' ']
[' ', ' ', 's', 'j', 's', ' ', 'i', 't', 'h', 's', 'i', ' ', 'u', 't', 'a']
['t', 'a', 't', 'u', ' ', 'i', 's', 'h', 't', 'i', ' ', 's', 'j', 's', ' ',
' ']
['e', ' ', ' ', 's', 'j', 's', ' ', 'i', 't', 'h', 's', 'i', ' ', 'u', 't',
'a', 't']
['s', 't', 'a', 't', 'u', ' ', 'i', 's', 'h', 't', 'i', ' ', 's', 'j', 's',
' ', ' ', 'e']
['t', 'e', ' ', ' ', 's', 'j', 's', ' ', 'i', 't', 'h', 's', 'i', ' ', 'u',
't', 'a', 't', 's']
So I figured maybe make it a generator (I'm not TO familiar with generators
yet so don't laugh) which changed my code just a slight bit:

        
                        
                        
                >>>mylist = []
def rev(x):
 
 
 
 
for char in x:
mylist.append(char)
mylist.reverse()
yield mylist
 

But even that threw me a curveball:

>>rev("this is just a test")

<generator object at 0x00D52170>

So how on earth would be the best way to: Write a function that takes a
string as an argument and outputs the letters backward, one per line.

It should look like the first char of every list in the top "working" code.

Any help woould be greatly apreciated, and a little bit of explaination as
to why you did it the way you did would be more helpful than just the code.

Thanks in advance

[Stefan Behnel]

Scott wrote:

So how on earth would be the best way to: Write a function that takes a
string as an argument and outputs the letters backward, one per line.

Homework?

Anyway, what about:

for c in string[::-1]:
print c
Stefan

[Will Maier]

On Wed, Jun 27, 2007 at 12:53:36PM -0400, Scott wrote:

So how on earth would be the best way to: Write a function that
takes a string as an argument and outputs the letters backward,
one per line.

>>def rev(forward):

... backward = list(forward)
... backward.revers e()
... return ''.join(backwar d)

>>rev("spam")

'maps'

list.reverse() changes the list in-place. Instead of iterating over
the items in the string sequence, you can just convert the input
string outright.

--

[Will Maier]-----------------[wi*******@ml1.n et|http://www.lfod.us/]

[Diez B. Roggisch]

Scott wrote:

Yeah I know strings == immutable, but question 1 in section 7.14 of "How
to think like a computer Scientist" has me trying to reverse one.

I've come up with two things, one works almost like it should except that
every traversal thru the string I've gotten it to repeat the "list" again.
This is what it looks like:

        
                        
                >>>>mylist = []
def rev(x):
 

 

            for char in x:

                mylist.append(char)

                mylist.reverse()

                print mylist