How to use getopt_long to parse a standard argument list in C.

getopt.c

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

const struct option longopts[] = {
  {"chdir", no_argument, NULL, 'd'},
  {"noclose", no_argument, NULL, 'n'},
  {"log-stdout", required_argument, NULL, '1'},
  {"log-stderr", required_argument, NULL, '2'},
  {0, 0, 0, 0}
};
const char* optstring = "dn1:2:";

int main (int argc, char** argv) {
  int a,b;
  // &b can be NULL if you don't need it
  while ((a = getopt_long(argc, argv, optstring, longopts, &b)) != -1) {
    printf("a: %d\nb: %d\noptarg: %s\n", a, b, optarg);
  }
  printf("optind: %d\n", optind);
  printf("extra: ");
  while (optind < argc) {
    printf("%s ", argv[optind++]);
  }
  printf("\n");
}