[Tutor] Error message...

[Mark Lawrence]

On 23/08/2012 16:33, Victoria Homsy wrote:
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> Dear All - sorry to bother you. I just tried to run this program:
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> def isPalindrome(s):
> if len(s) <= 1: return True
> else: return s[0] == s[-1] and isPalindrome (s[1:-1])
> isPalindrome('aba')
>
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> However when I run it in terminal it doesn't give me any answer - True or False. (I want the program to tell me whether the input string is True or False). In order to get an answer, I assume I would need to tell the program to print something. However I'm not sure where in the program I would do this. I tried this:
>
> def isPalindrome(s):
> if len(s) <= 1: return True and print "True"
> else: return s[0] == s[-1] and isPalindrome (s[1:-1])
> isPalindrome('aba')
>
> However, this does not work - I get another error message.
>
> Could somebody advise what I'm doing wrong here? Thank you.

You're not spending enough time thinking, seriously.  In your original 
attempt you've got isPalindrome which returns True or False.  You call 
the function but don't do anything with the return value, so it's simply 
discarded.  Then you mess around with a perfectly good function instead 
of fixing the real problem.  You've two options.  The simplest is :-

print 'isPalindrome returned', isPalindrome('aba')

The alternative which is used when you want to keep using a return value 
is :-

status = isPalindrome('aba')
print 'isPalindrome returned', status

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Whoops might have helped if I'd hit "Send".

-- 
Cheers.

Mark Lawrence.