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_flush() is called. The function returns TRUE when it successfully discarded one buffer and FALSE otherwise. 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).
The following example shows an easy way to get rid of all output buffers:
Nota: If the function fails it generates an E_NOTICE.
The boolean return value was added in PHP 4.2.0.