Like the string.* filters, the convert.* filters perform actions similar to their names. For more information on a given filter, refer to the manual page for the corresponding function.
Use of these filters are equivalent to processing all stream data through
the base64_encode() and base64_decode()
functions respectively.
convert.base64-encode supports parameters given as
an associative array. If line-length is given, the
base64 output will be split into chunks of line-length
characters each. If line-break-chars is given, each
chunk will be delimited by the characters given. These parameters give the
same effect as using base64_encode() with
chunk_split().
Example #1 convert.base64-encode & convert.base64-decode
<?php
$fp = fopen('php://output', 'w');
stream_filter_append($fp, 'convert.base64-encode');
fwrite($fp, "This is a test.\n");
fclose($fp);
/* Outputs: VGhpcyBpcyBhIHRlc3QuCg== */
$param = array('line-length' => 8, 'line-break-chars' => "\r\n");
$fp = fopen('php://output', 'w');
stream_filter_append($fp, 'convert.base64-encode', STREAM_FILTER_WRITE, $param);
fwrite($fp, "This is a test.\n");
fclose($fp);
/* Outputs: VGhpcyBp
: cyBhIHRl
: c3QuCg== */
$fp = fopen('php://output', 'w');
stream_filter_append($fp, 'convert.base64-decode');
fwrite($fp, "VGhpcyBpcyBhIHRlc3QuCg==");
fclose($fp);
/* Outputs: This is a test. */
?>
Use of the decode version of this filter is equivalent to processing all stream
data through the quoted_printable_decode() functions.
There is no function equivalent to convert.quoted-printable-encode.
convert.quoted-printable-encode supports parameters given as
an associative array. In addition to the parameters supported by
convert.base64-encode, convert.quoted-printable-encode
also supports boolean arguments binary and
force-encode-first.
convert.base64-decode only supports the
line-break-chars parameter as a type-hint
for stripping from the encoded payload.
Example #2 convert.quoted-printable-encode & convert.quoted-printable-decode
<?php
$fp = fopen('php://output', 'w');
stream_filter_append($fp, 'convert.quoted-printable-encode');
fwrite($fp, "This is a test.\n");
/* Outputs: =This is a test.=0A */
?>
The convert.iconv.* filters are available, if iconv support is enabled, and their use is equivalent to processing all stream data with iconv(). These filters do not support parameters, but instead expect the input and output encodings to be given as part of the filter name, i.e. either as convert.iconv.<input-encoding>.<output-encoding> or convert.iconv.<input-encoding>/<output-encoding> (both notations are semantically equivalent).
Example #3 convert.iconv.*
<?php
$fp = fopen('php://output', 'w');
stream_filter_append($fp, 'convert.iconv.utf-16le.utf-8');
fwrite($fp, "T\0h\0i\0s\0 \0i\0s\0 \0a\0 \0t\0e\0s\0t\0.\0\n\0");
fclose($fp);
/* Outputs: This is a test. */
?>