/* Example of Parsing Long Options with getopt_long.
   Copyright (C) 1991-2026 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License
   as published by the Free Software Foundation; either version 2
   of the License, or (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, see <https://www.gnu.org/licenses/>.
*/

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

/* Flag set by @samp{--verbose}.  */
static int verbose_flag;

int
main (int argc, char **argv)
{
  int c;

  while (1)
    {
      static struct option long_options[] =
	{
	  /* These options set a flag.  */
	  {"verbose", no_argument,       &verbose_flag, 1},
	  {"brief",   no_argument,       &verbose_flag, 0},
	  /* These options don't set a flag.
	     We distinguish them by their indices.  */
	  {"add",     no_argument,       0, 'a'},
	  {"append",  no_argument,       0, 'b'},
	  {"delete",  required_argument, 0, 'd'},
	  {"create",  required_argument, 0, 'c'},
	  {"file",    required_argument, 0, 'f'},
	  {0, 0, 0, 0}
	};
      /* @code{getopt_long} stores the option index here.  */
      int option_index = 0;

      c = getopt_long (argc, argv, "abc:d:f:",
		       long_options, &option_index);

      /* Detect the end of the options.  */
      if (c == -1)
	break;

      switch (c)
	{
	case 0:
	  /* If this option set a flag, do nothing else now.  */
	  if (long_options[option_index].flag != 0)
	    break;
	  printf ("option %s", long_options[option_index].name);
	  if (optarg)
	    printf (" with arg %s", optarg);
	  printf ("\n");
	  break;

	case 'a':
	  puts ("option -a");
	  break;

	case 'b':
	  puts ("option -b");
	  break;

	case 'c':
	  printf ("option -c with value '%s'\n", optarg);
	  break;

	case 'd':
	  printf ("option -d with value '%s'\n", optarg);
	  break;

	case 'f':
	  printf ("option -f with value '%s'\n", optarg);
	  break;

	case '?':
	  /* @code{getopt_long} already printed an error message.  */
	  break;

	default:
	  abort ();
	}
    }

  /* Instead of reporting @samp{--verbose}
     and @samp{--brief} as they are encountered,
     we report the final status resulting from them.  */
  if (verbose_flag)
    puts ("verbose flag is set");

  /* Print any remaining command line arguments (not options).  */
  if (optind < argc)
    {
      printf ("non-option ARGV-elements: ");
      while (optind < argc)
	printf ("%s ", argv[optind++]);
      putchar ('\n');
    }

  exit (0);
}
