C++ - Using a stack to determine if a C style string is a palindrome

Question

I'm working on an assignment for class. We were provided with these three classes. (Linked here, the editor was flipping out when I tried to do them on separate lines).

We're supposed to take in a string and then use these classes to test if it's a palindrome. We can't modify said classes.

And here's my int main:

#include <iostream>
#include <cstring>
#include <cctype>
#include "stack.h"

using namespace std;

int main () {
   char testString[100];
   Stack<char> charStack;

   cout << "Please enter a string:\n> ";
   cin.getline(testString, 100);

   char caps;
   for (int i = 0; i < strlen(testString); i++) {
      if (isalpha(testString[i])) {
         caps = toupper(testString[i]);
         charStack.push(caps);
      }
   }

   for (int j = 0; j < strlen(testString); j++) {
      if (isalpha(testString[j])) {
         caps = toupper(testString[j]);
         if (charStack.firstPtr->getData() == caps) { // This part is the issue. firstPtr is private in list.h, and I can't figure out another way to compare the char array to the data in the stack
            charStack.pop(caps);
         }
      }
   }

   if (charStack.isStackEmpty()) {
      cout << endl << endl << "\"" << testString << "\"  IS a palindrome." << endl;
   }
   else {
      cout << endl << endl << "\"" << testString << "\"  is NOT a palindrome." << endl;
   }
}

As you can see, I can't quite figure out how to compare the popped data to the data in the char array. The Stack class only returns a boolean, and the pointer to the ListNode object in class List is private, so I can't use the "getData" function of that class! Anyone have any tips that could help me out?

Thanks!

That's the assignment. Our professor is aware that it's much easier to do it other ways. — user1888527, Apr 23 '14 at 22:00
Are you kidding, having three links in 'these three classes' !??? — , Apr 23 '14 at 22:02
@DieterLücking: The editor thought I had code in my post when I tried to separate them by line. Sorry. — user1888527, Apr 23 '14 at 22:03
@indiv: Wait, how do I compare after popping? Edit: Actually, just figured it out! Didn't notice that "value" was passed in by reference. So I can just pass in a blank test char, then compare that to the c-string! Thanks! — user1888527, Apr 23 '14 at 22:05
Please tell your professor that `List` is missing a copy constructor, [which is bad](http://stackoverflow.com/q/4172722/592323). — leemes, Apr 23 '14 at 22:24
I don't understand why your stack `pop` method even takes an argument. Stacks pop elements off the top of the stack, which is why it's called a stack. — , Apr 24 '14 at 00:15

score 2 · Accepted Answer · answered Apr 23 '14 at 22:21

Look at function Stack::pop(STACKTYPE &data)

It takes a non-const reference argument in which it stores the element being removed (this actually happens in the implementation of List::removeFromFront(NODETYPE &value) ).

That means that you can pass a char to the pop() function and afterwards it will contain the data you're looking for.

C++ - Using a stack to determine if a C style string is a palindrome

1 Answers1

Linked