stream_filter_prepend
(PHP 4 >= 4.3.0, PHP 5)
stream_filter_prepend — Attach a filter to a stream
Description
$stream
, string $filtername
[, int $read_write
[, mixed $params
]] )
Adds filtername to the list of filters
attached to stream.
Parameters
-
stream -
The target stream.
-
filtername -
The filter name.
-
read_write -
By default, stream_filter_prepend() will attach the filter to the read filter chain if the file was opened for reading (i.e. File Mode: r, and/or +). The filter will also be attached to the write filter chain if the file was opened for writing (i.e. File Mode: w, a, and/or +).
STREAM_FILTER_READ,STREAM_FILTER_WRITE, and/orSTREAM_FILTER_ALLcan also be passed to theread_writeparameter to override this behavior. See stream_filter_append() for an example of using this parameter. -
params -
This filter will be added with the specified
paramsto the beginning of the list and will therefore be called first during stream operations. To add a filter to the end of the list, use stream_filter_append().
Return Values
Returns a resource which can be used to refer to this filter instance during a call to stream_filter_remove().
Changelog
| Version | Description |
|---|---|
| 5.1.0 |
Prior to PHP 5.1.0, this function returns TRUE on success
or FALSE on failure.
|
Notes
Note: When using custom (user) filters
stream_filter_register() must be called first in order to register the desired user filter tofiltername.
Note: Stream data is read from resources (both local and remote) in chunks, with any unconsumed data kept in internal buffers. When a new filter is prepended to a stream, data in the internal buffers, which has already been processed through other filters will not be reprocessed through the new filter at that time. This differs from the behavior of stream_filter_append().
Note: When a filter is added for read and write, two instances of the filter are created. stream_filter_prepend() must be called twice with
STREAM_FILTER_READandSTREAM_FILTER_WRITEto get both filter resources.
See Also
- stream_filter_register() - Register a user defined stream filter
- stream_filter_append() - Attach a filter to a stream
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