is_dir Tells whether the filename is a directory boolis_dir stringfilename Returns &true; if the filename exists and is a directory. If filename is a relative filename, it will be checked relative to the current working directory. The results of this function are cached. See clearstatcache for more details. This function will not work on remote files; the file to be examined must be accessible via the server's filesystem. See also chdir, dir, opendir, is_file and is_link.