/* File: pali1.c
   Checks if a string is a palindrome.
*/

#include<stdio.h>
#include"genlib.h"
#include"simpio.h"
#include"strlib.h"

/* Function Prototypes */
bool IsPalindrome(string str) ;

main() {
   string str ;

   printf("This program checks for palindromes.\n") ;
   printf("End the program by entering a blank line.\n") ;
   while (TRUE) {
      printf("String: ") ;
      str = GetLine() ;
      if ( StringEqual(str, "") ) break ;
      if ( IsPalindrome(str) ) {
	 printf("'%s' is a palindrome.\n", str) ;
      } else {
	 printf("'%s' is not a palindrome.\n", str) ;
      }
   } /* end while */
}

/* Function: IsPalindrome */
bool IsPalindrome(string str) {
   int i, n ;
   char front, back ;

   n = StringLength(str) ;
   for (i = 0 ; i < n/2 ; i++ ) {
      front = IthChar(str, i) ;
      back = IthChar(str, n - i - 1) ;
      if (front != back) return(FALSE) ;
   }
   return(TRUE) ;
}