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From: Nick Garoufalis on 5 Apr 2010 16:58
I need to check whether a word is a palindrome or not using recursion. this is what i have so far:

function result = isPalindrome(string)

size = length(string);
if length(string) == 1 || isempty(string)
result = 'true';

elseif string(1) == string(size)
string(1) = [];
string(size-1) = [];
result = isPalindrom(string);

else
result = 'false';
end
end

it gets caught up at the recursion part where i plug the string back in. Thanks for the help
From: Steven Lord on 5 Apr 2010 17:56

"Nick Garoufalis" <Nickg5859(a)gmail.com> wrote in message
news:hpdiss$7b5$1(a)fred.mathworks.com...
>I need to check whether a word is a palindrome or not using recursion. this
>is what i have so far:
>
> function result = isPalindrome(string)
>
> size = length(string);

There's no need to shadow the SIZE function with a variable like this.

> if length(string) == 1 || isempty(string)

I would use ISSCALAR here instead of checking LENGTH, personally.

> result = 'true';

Do you mean to return a string here, or do you want to return a logical
value? If the latter, use:

result = true;

> elseif string(1) == string(size)

Use END to refer to the last element of the string:

elseif string(1) == string(end)

> string(1) = [];
> string(size-1) = [];
> result = isPalindrom(string);

You don't need to delete the elements from string; just pass in a substring.

result = isPalindrome(string(2:end-1));

[Exercise: prove that string(2:end-1)) will not error.]

I also assume the "isPalindrom" was a typo in your newsgroup posting, not in
the actual code?

> else
> result = 'false';

Same comment as above --

result = false;

> end
> end
>
> it gets caught up at the recursion part where i plug the string back in.
> Thanks for the help

If the comments above don't resolve the problem, you should clarify what you
mean by "it gets caught up".

--
Steve Lord
slord(a)mathworks.com
comp.soft-sys.matlab (CSSM) FAQ: http://matlabwiki.mathworks.com/MATLAB_FAQ


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