stream_filter_append

(PHP 4 >= 4.3.0, PHP 5)

stream_filter_append — Attach a filter to a stream

说明

resource stream_filter_append ( resource $stream , string $filtername [, int $read_write [, mixed $params ]] )

Adds filtername to the list of filters attached to stream.

参数

stream: The target stream.
filtername: The filter name.
read_write: By default, stream_filter_append() 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/or STREAM_FILTER_ALL can also be passed to the read_write parameter to override this behavior.
params: This filter will be added with the specified params to the end of the list and will therefore be called last during stream operations. To add a filter to the beginning of the list, use stream_filter_prepend().

返回值

Returns a resource which can be used to refer to this filter instance during a call to stream_filter_remove().

更新日志

版本	说明
5.1.0	Prior to PHP 5.1.0, this function returns `TRUE` on success 或者在失败时返回 `FALSE`.

范例

Example #1 Controlling where filters are applied


<?php

$fp = fopen('test.txt', 'w+');


stream_filter_append($fp, "string.rot13", STREAM_FILTER_WRITE);


fwrite($fp, "This is a test
");


rewind($fp);


fpassthru($fp);

fclose($fp);


?>

注释

Note: When using custom (user) filters
stream_filter_register() must be called first in order to register the desired user filter to filtername.

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 appended to a stream, data in the internal buffers is processed through the new filter at that time. This differs from the behavior of stream_filter_prepend().

Note: When a filter is added for read and write, two instances of the filter are created. stream_filter_append() must be called twice with STREAM_FILTER_READ and STREAM_FILTER_WRITE to get both filter resources.