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

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

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

  if (argc < 2) {
    fprintf(stderr, "No arguments provided.\n");
    return 1;
  }

  for (int i = 1; i < argc; i++) {
    while (!strncmp(argv[i], "-", 1) || !opendir(argv[i]))
      i++;
    
    d = opendir(argv[i]);
    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); 
  }
}