This function discards the contents of the topmost output buffer and turns off this output buffering. If you want to further process the buffer's contents you have to call ob_get_contents() before ob_end_clean() as the buffer contents are discarded when ob_end_clean() is called.
Returns TRUE on success or FALSE on failure. Reasons for failure are first that you called the function without an active buffer or that for some reason a buffer could not be deleted (possible for special buffer).