Returns a directory handle to be used in subsequent closedir(), readdir(), and rewinddir() calls.
If path is not a valid directory or the directory can not be opened due to permission restrictions or filesystem errors, opendir() returns FALSE and generates a PHP error of level E_WARNING. You can suppress the error output of opendir() by prepending '@' to the front of the function name.
As of PHP 4.3.0 path can also be any URL which supports directory listing, however only the file:// url wrapper supports this in PHP 4.3. As of PHP 5.0.0, support for the ftp:// url wrapper is included as well.