Operations Allowed On Buffers
The operations allowed on buffers can be controlled
by passing one of the
buffer control flags
to ob_start's third
flags parameter.
If omitted, all operations are allowed by default.
If 0 is used instead,
the buffer cannot be flushed, cleaned or removed
but it's contents can still be retrieved.
PHP_OUTPUT_HANDLER_CLEANABLE allows
ob_clean to clean the contents of the buffer.
警告
The absence of the PHP_OUTPUT_HANDLER_CLEANABLE flag
will not prevent ob_end_clean
or ob_get_clean from clearing the contents of the buffer.
PHP_OUTPUT_HANDLER_FLUSHABLE allows
ob_flush to flush the contents of the buffer.
警告
The absence of the PHP_OUTPUT_HANDLER_FLUSHABLE flag
will not prevent ob_end_flush
or ob_get_flush from flushing the contents of the buffer.
PHP_OUTPUT_HANDLER_REMOVABLE allows
ob_end_clean, ob_end_flush,
ob_get_clean or ob_get_flush
to turn off the buffer.
PHP_OUTPUT_HANDLER_STDFLAGS,
the combination of the three flags will allow each of the three operations
to be performed on the buffer.