The closedir function closes a directory stream and frees
    the structure associated with the dir_pointer argument. Upon
    return, the value of dir_pointer does not necessarily point to an
    accessible object of the type DIR.

    The type DIR, which is defined in the <dirent.h> header file,
    represents a directory stream that is an ordered sequence of
    all the directory entries in a particular directory. Directory
    entries represent files. You can remove files from or add files
    to a directory asynchronously to the operation of the readdir
    function.

                                   NOTE

       An open directory must always be closed with the closedir
       function to ensure that the next attempt to open the
       directory is successful.