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

int main(int argc, char **argv)
{
    if (argc > 2)
        return 1;

    DIR *d;
    if (argc == 1)
    {
        d = opendir(".");
        if (!d)
        {
            fprintf(stderr, "simple_ls: .: No such file or directory\n");
            return 1;
        }
    }
    else
    {
        d = opendir(argv[1]);
        if (!d)
        {
            fprintf(stderr, "simple_ls: %s: No such file or directory\n",
                    argv[1]);
            return 1;
        }
    }

    struct dirent *dir;
    while ((dir = readdir(d)))
    {
        if (dir->d_name[0] != '.')
            printf("%s\n", dir->d_name);
    }

    if (closedir(d))
        return 1;

    return 0;
}