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This document uses PHP Chinese website manual Release
(PHP 5, PHP 7)
iconv_mime_encode — Composes a MIME header field
$field_name
, string $field_value
[, array $preferences
= NULL
] )Composes and returns a string that represents a valid MIME header field, which looks like the following:
Subject: =?ISO-8859-1?Q?Pr=FCfung_f=FCr?= Entwerfen von einer MIME kopfzeile
field_name
The field name.
field_value
The field value.
preferences
You can control the behaviour of iconv_mime_encode()
by specifying an associative array that contains configuration items
to the optional third parameter preferences
.
The items supported by iconv_mime_encode() are
listed below. Note that item names are treated case-sensitive.
Item | Type | Description | Default value | Example |
---|---|---|---|---|
scheme | string | Specifies the method to encode a field value by. The value of this item may be either "B" or "Q", where "B" stands for base64 encoding scheme and "Q" stands for quoted-printable encoding scheme. | B | B |
input-charset | string |
Specifies the character set in which the first parameter
field_name and the second parameter
field_value are presented. If not given,
iconv_mime_encode() assumes those parameters
are presented to it in the
iconv.internal_encoding
ini setting.
| iconv.internal_encoding | ISO-8859-1 |
output-charset | string | Specifies the character set to use to compose the MIME header. | iconv.internal_encoding | UTF-8 |
line-length | integer | Specifies the maximum length of the header lines. The resulting header is "folded" to a set of multiple lines in case the resulting header field would be longer than the value of this parameter, according to » RFC2822 - Internet Message Format. If not given, the length will be limited to 76 characters. | 76 | 996 |
line-break-chars | string | Specifies the sequence of characters to append to each line as an end-of-line sign when "folding" is performed on a long header field. If not given, this defaults to "\r\n" (CR LF). Note that this parameter is always treated as an ASCII string regardless of the value of input-charset. | \r\n | \n |
Returns an encoded MIME field on success,
or FALSE
if an error occurs during the encoding.
Example #1 iconv_mime_encode() example
<?php
$preferences = array(
"input-charset" => "ISO-8859-1" ,
"output-charset" => "UTF-8" ,
"line-length" => 76 ,
"line-break-chars" => "\n"
);
$preferences [ "scheme" ] = "Q" ;
// This yields "Subject: =?UTF-8?Q?Pr=C3=BCfung=20Pr=C3=BCfung?="
echo iconv_mime_encode ( "Subject" , "Prüfung Prüfung" , $preferences );
$preferences [ "scheme" ] = "B" ;
// This yields "Subject: =?UTF-8?B?UHLDvGZ1bmcgUHLDvGZ1bmc=?="
echo iconv_mime_encode ( "Subject" , "Prüfung Prüfung" , $preferences );
?>
[#1] cedric at gn dot apc dot org [2012-03-13 15:54:12]
iconv_mime_encode() isn't directly suitable for encoding headers which include "specials" as described in RFC 1522 s4 & s5, for example
<?php
$mimeprefs = array ("scheme" => "Q",
"input-charset" => "utf-8",
"output-charset" => "utf-8",
"line-break-chars" => "\n");
$enc = iconv_mime_encode('From', '"R??al Nam??" <user@example.com>', $prefs);
?>
will wrongly attempt to encode the angle brackets. To use the function in place of mb_encode_mimeheader(), instead you need to encode the words separately, removing the superfluous field name:
<?php
$encoded = "From: \"". preg_replace('/^:\s+/', '', iconv_mime_encode("", $real, $mimeprefs))."\" <$email>";
?>
Also, values of "line-length" greater than 76 would be illegal under RFC 1522 and resulting encoded words may not be recognised. (Not tested, but 72 would be safer.)
[#2] markus AT birth MINUS online DOT de [2010-05-19 05:38:53]
Looks like this function suffers from the same bug as mb_encode_mime() with long strings of non us-ascii characters. The function then returns false. This applies for utf-8 to utf-8 "conversion".
<?php
$subject = '???? ??????????? ??????: ????????? > ????????';
$prefs = array(
'scheme' => 'Q',
'input-charset' => 'UTF-8',
'output-charset' => 'UTF-8',
'line-length' => 76,
'line-break-chars' => "\r\n",
);
echo 'Original: ' . $subject . PHP_EOL;
$enc = iconv_mime_encode( 'Subject', $subject, $prefs );
var_dump( $enc ); // will show bool(false)
?>
As a workaround, you could explode() the value on spaces and encode each word separately. Then remove the "Subject: " in front of the resulting strings and join() them with "\r\n " (don't forget the SPACE after the \n) as separator.