//  this program will read a string and determine whether it is a 
//  palindrome (a string is a palindrome if it is the same forwards and 
//  backwards, ignoring capitalization and punctuation)
//
//  the user is prompted to enter the string in lowercase. the program 
//  reads each character. as the characters are read they are checked, 
//  and if the character is a letter then the character is pushed on a 
//  stack and added to a queue. the stack then contains the reverse of the
//  original string and the queue contains the original string. these two 
//  strings are compared; if they are equal then the string is a palindrome.

#include "stacklst.h"
#include "queuelst.h"
#include 

int main()
{
   Stack chstack;      	//  stack to hold reversed string
   Queue chqueue;     	//  queue to hold original string
   char inchar;         //  character entered by user
   char stchar;         //  character popped from stack
   char qchar;          //  character removed from queue
   int ispalindrome;    //  flag: is the string a palindrome?
   int ok;              //  flag: did the stack/queue overflow?

//  initialize, then read string and create original and reversed
//  versions using the stack and queue

   ok = 1;
   cout << "Enter a line of text (all lowercase)\n";
   inchar = cin.get();
   while (inchar != '\n' && ok)
   {
      if (inchar != ' ')
      {
         ok = chstack.push(inchar);
         ok = chqueue.insert(inchar);
         inchar = cin.get();
      }
   }   //  end while

//  get one character at a time from each string and compare them. if
//  they ever differ then the string was not a palindrome

   if (ok)
   {
      ispalindrome = 1;
      while (!chstack.isEmpty() && !chqueue.isEmpty() && ispalindrome)
      {
         ok = chstack.pop(stchar);
         ok = chqueue.del(qchar);
         if (stchar != qchar)
            ispalindrome = 0;
      }    //  end while

//  check ispalindrome to find out whether the two strings matched
//  everywhere
      if (ispalindrome)
         cout << "The string is a palindrome\n";
      else
         cout << "The string is not a palindrome\n";
   }
   else
      cout << "Error: phrase is too long to check\n";
}

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