using a linked list to store a word and determine whether its a palindrome

OK, how much do you know about structs and pointers (or references)? I'm guessing, you'll need that knowledge to create a linked list.

Now, I'll assume, you have your linked list, that looks something like this:

A <-> N <-> N <-> A

Then you can have a pointer to the first and last element. If the contents of both of these Elements are equal, go to the second first and second last and so on. If there's a difference somewhere, cancel. Then, you don't have a Palindrome.

Greetings,
Nepomuk

i know the theory behind linked lists but the thing is i've never created one before. is this how you would create simple linked list? if not can you please guide me here?

struct word {
char letter;
struct word *nodeptr;
};

in my program i would like to check one word and then either exit the program or check another word. if i choose to check another word, should i add to the back of the linked list (like in a queue)?

Quote: Originally Posted by chungjoel is this how you would create simple linked list? if not can you please guide me here? Code: ( text ) struct word { char letter; struct word *nodeptr; };

Seems fine to me for a simple linked list (but I still am quite new to C/C++, so I might have missed something), but I thought you wanted "the nodes in the palindrome [to] be double pointer nodes"?

Quote: Originally Posted by chungjoel in my program i would like to check one word and then either exit the program or check another word. if i choose to check another word, should i add to the back of the linked list (like in a queue)?

If you did that, your linked list would become longer and longer and longer. Why do that? Why not basically create a new list every time you get a new word?

Greetings,
Nepomuk

PS.: Check out the CODE tags. The make code look so much better!

Quote: Originally Posted by i would like to store a word in a linked list

Why? Are you required to do this, or is it a design choice you made yourself? I'll presume it's required, unless you say otherwise.

Quote: Originally Posted by the nodes in the palindrome should be double pointer nodes

Clarify. This is a nonsensical statement, and has to be interpreted to some reasonable approximation.

Just realized, you made a mistake here:

Quote: Originally Posted by chungjoel Code: ( text ) struct word { char letter; struct word *nodeptr; };

should be for a single sided list.

By the way, I've just written such a program in C++ and it works as suggested. I won't give you the code of course, but if you have specific questions, I can check them with my own version.

Greetings,
Nepomuk

This doesn't sound too bad.

Your double pointer nodes allow a traverse of the list in either direction. This is a standard double-linked list.

Be careful about checking your palindrome sionce the palindrome may have several words: "Madam, I'm Adam" or "A Man A Plan A Canal Panama". In these cases the words themselves are not palindromes but the phrase is. That means you will probably have a separate list for each palindrome.

There are plenty of tutorials on how to do a linked list. It is certainly well worth your time you learn how to do this. I like the book Teach Yourself Data Structures and Algorithms by Robert LaFore.

Hi again!

Something I realized is, that you can easily forget to ignore case (I'm guessing, you want A == a to be valid in your test) and punctuation (ignore dots, commas, etc.). For that, note that 'a' < 'z' as well as 'A' < 'Z' and 'A'-'a'=32.

When you've finished your program, of course you should test it. I'd recommend Weird Al Yankovic's song Bob where every single line is a Palindrome. ^^ (Of course, you can just enjoy the song on YouTube.)

Greetings,
Nepomuk

this was really helpful. thanks a lot.