Determining if string is palindrome

Question

I wrote two simple functions to determine if a string is a palindrome. I thought they were equivalent, but 2 doesn't work. Why is this?

1

def is_palindrome(string):
    if string == string[::-1]:
        return True
    else:
        return False

2

def is_palindrome(string):
    if string == reversed(string):
        return True
    else:
        return False

Answer 1

reversed doesn't create a string but a 'reversed' object:

>>> reversed('radar')
<reversed object at 0x1102f99d0>

As such, the string 'radar' does not compare equal to the object reversed('radar'). To make it work, you need to make sure the reversed object is actually evaluated:

def is_palindrome(string):
    if string == u''.join(reversed(string)):
        return True
    else:
        return False

The u''.join(reversed(string)) inserts u'' in between each of the characters in the string and this leads to the reversed string being turned into a string object.

Answer 2

In the second one, you need to make a str from the reversed type instance -- it's not hard:

if string == ''.join(reversed(string)):