PHP Manual: iconv_mime

Description

string iconv_mime_encode ( string field_name, string field_value [, array preferences] )

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

In the above example, "Subject" is the field name and the portion that begins with "=?ISO-8859-1?..." is the field value.

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.

Table 1. Configuration items supported by iconv_mime_encode()

Item	Type	Description	Default value	Example
scheme	boolean	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_charset ini setting.	iconv.internal_charset	ISO-8859-1
output-charset	string	Specifies the character set to use to compose the `MIME` header. If not given, the same value as `input-charset` will be used.	the same value as `input-charset`	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

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_Pr=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);
?>