Gets the current buffer contents and delete current output buffer.
ob_get_clean essentially executes both ob_get_contents and ob_end_clean.
The output buffer must be started by ob_start with PHP_OUTPUT_HANDLER_CLEANABLE and PHP_OUTPUT_HANDLER_REMOVABLE flags. Otherwise ob_get_clean will not work.
This function has no parameters.
Returns the contents of the output buffer and end output buffering. If output buffering isn't active then false is returned.