/*****************************************
 * palindrome.c                          *
 *                                       *
 * A program to check if a string is a   *
 * palindrome.                           *
 *****************************************/

#include <stdio.h>

/* Function prototype */
int isPali(char []);

int main()
{
  /* Declare variables to store the palindrome */
  char str1[100];
  char str2[100];

  /* Declare and initialize sentinel value */
  char sent[] = "-999";

  /* Loop variables */
  int i, j;

  /* Boolean flag */
  int flag = 0;

  /* Obtain input */
  fgets(str1, sizeof(str1), stdin);
  str1[strlen(str1)-1] = '\0';


  /* Begin sentinel loop */
  while(strcmp(str1,sent) != 0)
  {
    /* Ignore all whitespace and special characters in the palindrome */

    j = 0;
    for(i = 0; i < strlen(str1); i++)
    {
      if(str1[i] <= 'z' && str1[i] >= 'a')
      {
        str2[j] = str1[i];
        j++;
      }
      else if (str1[i] <= 'Z' && str1[i] >= 'A')
      {
        str2[j] = str1[i] + 32;
        j++;
      }
    }

    str2[j] = '\0';

    /* Use the function to check if the string is a palindrome */
    if( isPali(str2) )
      printf("This string is a palindrome\n");
    else
      printf("This string is not a palindrome\n");


    /* Read in the string again */
    fgets(str1, sizeof(str1), stdin);
    str1[strlen(str1)-1] = '\0';

  }

  return 0;

}

int isPali(char str[])
{
    int i, j;

    /* If we find mismatched characters return false */
    for(i = 0, j = strlen(str)-1; i < j; i++, j--)
      if(str[j] != str[i])
        return 0;

    /* If the loop finishes without returning zero then the string is a
     * palindrome, so return true.
     */

    return 1;
}