//----------------------------------------------------------------------------
//
//   FILE           :   palindrome.C
//   AUTHOR         :   Eugene Wallingford
//   CREATION DATE  :   October 29, 1997
//
//----------------------------------------------------------------------------
//
//   MODIFIED BY    :   
//   DATE           :   
//   DESCRIPTION    :   
//
//----------------------------------------------------------------------------

#include <iostream.h>
#include "list.h"    // header for List  -- ListElementType  is char
#include "stack.h"   // header for Stack -- StackElementType is char

int palindrome  ( List & );
int display_list( List & );

int main()
{
   char word_as_string[21];
   cout << "Enter a string of up to 20 characters:  ";
   cin  >> word_as_string;

   List l;
   for (int i = 0; word_as_string[i] != '\0'; i++)
       l.insert(word_as_string[i]);

   if ( palindrome( l ) )
      cout << "Yes!  This word is a palindrome: ";
   else
     cout << "No, sorry, but this word is not a palindrome: ";
   display_list( l );
}

int palindrome  ( List & word )
{
   Stack            s;
   StackElementType ch;

   // build the stack
   if ( word.first( ch ) )
   {
      s.push( ch );
      while ( word.next( ch ) )
            s.push( ch );
   }

   // compare forwards and backwards
   word.first( ch );
   while ( !s.isEmpty() )
   {
      if ( s.pop() != ch )
         return 0;
      word.next( ch );
   }

   return 1;
}

int display_list( List & l )
{
   ListElementType elem;
   bool notEmpty(l.first(elem));
   while (notEmpty)
   {
      cout << elem;
      notEmpty = l.next(elem);
   }
   cout << endl << endl;
}