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Andrew Merrick
20,151 PointsWays to reverse a string in Python?
This is in reference to the Stringcases challenge in the Tuples section of Python collections: http://teamtreehouse.com/library/stringcases
I was able to pass but I was wondering if there's a built in method to reverse a string, i.e. my_string.reverse()?
my_string.reverse() and my_string.reversed()
did not work since, I believe, they only apply to lists. I found out another way using slicing, but is there a method to reverse a string in Python?
3 Answers
Stone Preston
42,016 PointsI think you can use
''.join(reversed(my_string))
if you dont want to use slicing
Pierre Guiglion
11,583 PointsYou can also use:
my_string[::-1]
It actually "slices" your string, going through all of it, by steps of -1. The slicing syntax is:
[<start>:<end>:<step>]
Andrew Merrick
20,151 PointsThanks, Pierre. That's actually how I was able to pass the challenge. Thanks for the help.
Stephen Whitfield
16,771 Points
Andrew Merrick
20,151 PointsStephen:
I tried using the my_string.reverse() (which I originally found on the link you provided), i.e.:
my_string = "hello world!"
my_string.reverse()
but I received a Traceback error:
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'str' object has no attribute 'reverse'
I think the list.reverse() only works for lists and not strings, but I could be mistaken. I think the:
"".join(reverse(my_string))
and
my_string[::-1]
are the better options. Thanks for the help, though!
Kenneth Love
Treehouse Guest TeacherWe're using Python 3, though. Strings haven't changed much, but be careful about using Python 2 docs.
Stephen Whitfield
16,771 PointsAndrew Merrick Apologies. That's correct. .reverse() only works on lists. I was actually suggesting that you split the string into letters, reverse that list, and join them back together all in one line of code. my_string[::-1] is a far better solution though.
Andrew Merrick
20,151 PointsAndrew Merrick
20,151 PointsThanks, Stone! That worked as well.