# iconv_mime_encode

(PHP 5, PHP 7)

iconv_mime_encode — Composes a MIME header field

### 说明

iconv_mime_encode ( string `$field_name` , string `$field_value` [, array `$preferences` = `NULL` ] ) : string

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.

### 参数

`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.

  Configuration items supported by iconv_mime_encode()
  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

### 返回值

Returns an encoded MIME field on success, or `FALSE` if an error occurs during the encoding.

### 范例

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);
    ?>

### 参见

- imap_binary() - Convert an 8bit string to a base64 string
- mb_encode_mimeheader() - 为 MIME 头编码字符串
- imap_8bit() - Convert an 8bit string to a quoted-printable string
- quoted_printable_encode() - 将 8-bit 字符串转换成 quoted-printable 字符串