/**
 * exptui.c
 *   A simple user interface for the exponentiation procedures.
 *   Copyright (c) 2010 Samuel A. Rebelsky
 *   Released under GPL 3.0
 */

/* +---------+--------------------------------------------------------
 * | Headers |
 * +---------+
 */

/* stdlib.h supplies strtol. */
#include <stdlib.h>     
/* stdio.h supplies printf and fprintf. */
#include <stdio.h>
/* errno.h supplies errno, which is used for error checking in strtol. */
#include <errno.h>

/* +------+-----------------------------------------------------------
 * | Main |
 * +------+
 */

int
main (int argc, char **argv)
{
  if (argc != 3)
    {
      fprintf (stderr, 
               "%s: Expects two parameters, received %d.\n", 
               argv[0], argc);
      exit (EXIT_FAILURE);
    }

  errno = 0;
  long x = strtol (argv[1], (char **) NULL, 10);
  if (errno != 0)
    {
      fprintf (stderr, "exptui: Invalid parameter: %s.\n", argv[0]);
      exit (EXIT_FAILURE);
    }

  long y = strtol (argv[2], (char **) NULL, 10);
  if (errno != 0)
    {
      fprintf (stderr, "exptui: Invalid parameter: %s.\n", argv[0]);
      exit (EXIT_FAILURE);
    }

  long result = expt (x, y);

  printf("%d^%d = %d\n", x, y, result);
  exit (EXIT_SUCCESS);
} /* main (int, char **) */