/*
 * Ask user for a word and print it forwards and backwards.
 * CSE 303 demo (for debugging), 10/08.  HP
 */

#define MAX_STR 100   /* length of longest input string */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/* Return a new string with the contents of s backwards */
char * reverse(char * s) {
  char * result;            /* the reversed string */
  int L, R;
  char ch;

  /* allocate enought space for a copy of s */
  result = (char *) malloc((strlen(s)+1)*sizeof(char));

  /* copy original string then reverse and return the copy */
  strcpy(result,s);

  L = 0;
  R = strlen(result)-1;
  while (L < R) {
    ch = result[L];
    result[L] = result[R];
    result[R] = ch;
    L++; R--;
  }

  return result;
}


/* Ask the user for a string, then print it forwards and backwards.     */
/* Warning: not entirely safe: assumes the user input will have no more */
/* than MAX_STR-1 characters. It also does not test for EOF.            */
int main() {
  char line[MAX_STR];    /* original input line */
  char * rev_line;       /* backwards copy from reverse function */

  printf("Please enter a string: ");
  gets(line);
  rev_line = reverse(line);
  printf("The original string was:   >%s<\n", line);
  printf("Backwards, that string is: >%s<\n", rev_line);
  printf("Thank you for trying our program.\n");
  return 0;
}