a expamle of getopt_long

getopt_long.c

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

/* Flag set by ‘--verbose’. */
static int verbose_flag;

int main(int argc, const 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}};
    /* 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\n");
      break;

    case 'b':
      puts("option -b\n");
      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 '?':
      /* getopt_long already printed an error message. */
      break;

    default:
      abort();
    }
  }

  /* Instead of reporting ‘--verbose’
     and ‘--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);
}