In PHP, iconv_mime_encode() function is used to composes a MIME header field. This is an inbuilt PHP function.
Syntax
string iconv_mime_encode(string $field_name, string $field_value, array $options=[])
The iconv_mime_encode() function is used to compose and return a string that represents a valid MIME header field, which looks like -
Subject: =ISO-8859-1?Q?Pr=FCfung_f=FFCr?= Entwerfen von einer MIME kopfzeile
Note− In the above example, Subject - is the field name, and the portion that begins with "=ISO-8859-1?..." is the field value.
Parameters
iconv_mime_encode() accepts three different parameters − $field_name, $field_value and $options.
$field_name − This parameter is used for the field name.
$field_value − This parameter is used for the field value.
$options − Using this parameter, you can control the behavior of the iconv_mime_encode() by specifying an associative array that contains configuration items to the optional parameter.
Following is the list of configuration items supported by iconv_mime_encode()
Item | Type | Description | Default Value | Example |
|---|---|---|---|---|
| scheme | string | The scheme specifies the method to encode a field value by. This item value may be either B (base64) or Q(quoted-printable) encoding scheme. | ||
| input-charset | string | It specifies the character set, the field_name is the first parameter and field_value is the second parameter. If these parameters are not given then the iconv_mime_encode() function assumes that it may be presented in the iconv.internal_charset ini setting. | iconv.internal_charset | ISO-8859-1 |
| output-charset | string | It specifies the character set to use to compose the MIME header. If it is not given then it will use the input-charset value. | input_charset is use as a default value | UTF-8 |
| line-length | integer | It specifies the maximum length of the header lines. | 76 | 996 |
| line-break-chars | string | It specifies the sequence of characters to append to each line as an EOL when folding is performed on a long header field. If it is not given then this default to “\r\n” (CR LF) | \r\n | \n |
Example 1 - Using "Q" quoted-printable encoding scheme
<?php
// used configuration items supported by iconv_mime_encode()
$options = array(
"input-charset" => "ISO-8859-2",
"output-charset" => "UTF-8",
"line-length" => 76,
"line-break-chars" => "\n"
);
// Q quoted-printable encoding scheme is used
$options["scheme"] = "Q";
// Below code will show the result as
// "Subject: =?UTF-8?Q?Pr=C3=BCfung=20Pr=C3=BCfung?="
echo iconv_mime_encode("Subject", "Prüfung Prüfung", $options);
?>Output
Subject: =?UTF-8?Q?Pr=C3=83=C2=BCfung=20Pr=C3=83=C2=BCfung?=
Example 2
<?php
// used configuration items supported by iconv_mime_encode()
$options = array(
"input-charset" => "ISO-8859-1",
"output-charset" => "UTF-8",
"line-length" => 76,
"line-break-chars" => "\n"
);
// B base64 encoding scheme is used
$options["scheme"] = "B";
// Below code will show the result as
//"Subject: =?UTF-8?B?UHJlw4PCp29zIE9sw4PCoC50eHQ=?="
echo iconv_mime_encode("Subject", "Preços Olà.txt", $options);
?>Output
Subject: =?UTF-8?B?UHJlw4PCp29zIE9sw4PCoC50eHQ=?=