Example of Getopt

getopt.c

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <unistd.h>
#include <ctype.h>

int main(int argc, const char *argv[]) {
  bool aflag = false;
  bool bflag = false;

  char *cvalue = NULL;
  int c;

  opterr = 0;

  while ((c = getopt(argc, argv, "abc:")) != -1) {
    switch (c) {
      case 'a':
        aflag = true;
        break;
      case 'b':
        bflag = true;
        break;
      case 'c':
        cvalue = optarg;
        break;
      case '?':
        if (optopt == 'c') {
          fprintf(stderr, "Option -%c requires an argument.\n", optopt);
        } else if (isprint(optopt)) {
          fprintf(stderr, "Unknown option -%c.\n", optopt);
        } else {
          fprintf(stderr, "Unknown option character '\\x%x'\n", optopt);
        }
        return 1;
      default:
        abort();
    }
  }

  printf("aflag = %d,bflag = %d,cvalue = %s\n",
    aflag, bflag, cvalue);

  for (size_t index = optind; index < argc; index++) {
    printf("Non option arguments %s\n", argv[index]);
  }

  return 0;
}