#include <dirent.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

int main(int argc, char *argv[])
{
  DIR *d;
  char *dirs;
  struct dirent *dir;
  int hidden = 1;
  int c;

  while ((c = getopt(argc, argv, "a")) != -1) {
    switch (c) {
      case 'a': hidden = 0; break;
    }
  }

  if (argc > 0) {
    for (int i = 1; i < argc; i++) {
      dirs = argv[i];
      if ((d = opendir(dirs))) {
        while ((dir = readdir(d)) != NULL) {
          if (strncmp(dir->d_name, ".", 1) != 0 && hidden) /* dont print hidden files */
            printf("%s\n", dir->d_name);
          else if (!hidden)
            printf("%s\n", dir->d_name);
        }
        closedir(d); 
      }
    }
  }
}