if (""->file_exists ()) ...                                                    /* "ERR_EMPTY_FILE_NAME" */

if (""->directory_exists ()) ...                                               /* "ERR_EMPTY_DIRECTORY_NAME" */

if ("?*><"->file_exists ()) ...                                                /* "ERR_INCORRECT_FILE_NAME" */

if ("?*><"->directory_exists ()) ...                                           /* "ERR_INCORRECT_DIRECTORY_NAME" */