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| LONG WINAPI MimeDecodeTextEx( |
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UINT nCharacterSet, |
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UINT nEncodingType, |
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DWORD dwReserved, |
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LPCTSTR lpszInput, |
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LONG cchInput, |
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LPTSTR lpszOutput, |
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LONG cchOutput |
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The MimeDecodeTextEx function decodes a string which was
previously encoded using base64 or quoted-printable encoding. This
extended version of the function enables the caller to specify the
character set for the original text.
Parameters
- nCharacterSet
- A numeric identifier which specifies the
character set to use when decoding the input text. A value of zero
specifies the character set is undefined and no Unicode text
conversion is performed when the input string is decoded. If this
value does not match the character set used when the text was
originally encoded, the resulting output text may be invalid.
- nEncodingType
- An integer value that specifies the encoding method used. It may
be zero or one of the following values:
| Constant |
Description |
| MIME_ENCODING_QUOTED |
Quoted-printable encoding is designed for textual messages
where most of the characters are represented by the ASCII
character set and is generally human-readable. Non-printable
characters or 8-bit characters with the high bit set are
encoded as hexadecimal values and represented as 7-bit text.
Quoted-printable encoding is typically used for messages which
use character sets such as ISO-8859-1, as well as those which
use HTML. |
| MIME_ENCODING_BASE64 |
Base64 encoding converts binary or text data to ASCII by
translating it so each base64 digit represents 6 bits of data.
This encoding method is commonly used with messages that contain
binary data (such as binary file attachments), or when text uses
extended characters that cannot be represented by 7-bit ASCII.
It is recommended that you use base64 encoding with Unicode
text. This is the default encoding type used by this function. |
- dwReserved
- An integer value reserved for internal use. This value must
always be zero.
- lpszInput
- A pointer to a null terminated string which contains the encoded
text. This parameter cannot be a NULL pointer.
- cchInput
- An integer value which specifies the number of characters of
text in the input string which should be decoded. If this value is
-1, the entire length of the string up to the terminating null will
be decoded.
- lpszOutput
- A pointer to a string buffer that will contain the decoded text.
This buffer must be large enough to store all of the characters in
the decoded text, including the terminating null character. This
parameter cannot be NULL.
- cchOutput
- An integer value which specifies the maximum number of
characters which can be copied into the output string buffer. The
buffer must be large enough to store all of the decoded text and
terminating null character. This value must be greater than zero.
Return Value
If the input buffer can be successfully decoded, the return value is the
length of the decoded output string. If the function returns zero,
then no text was decoded and the output string buffer will be empty.
If the function fails, the return value is MIME_ERROR. To get
extended error information, call MimeGetLastError.
Remarks
This function provides a means to decode text that was previously
encoded using either base64 or quoted-printable encoding. In most
cases, it is not necessary to use this function because the message
parser will detect which character set and encoding was used, then
automatically decode the message text if necessary.
The value of the nCharacterSet parameter does not affect
the resulting output text, it is only used when decoding the input
text. If the Unicode version of this function is called, the output
text will be converted to UTF-16 and returned to the caller. If the
ANSI version of this function is used, the decoded output will always
be returned to the caller using the UTF-8 character set.
If the nCharacterSet parameter is specified as
MIME_CHARSET_UTF16, the encoding type must be MIME_ENCODING_BASE64.
Other encoding methods are not supported for Unicode strings and will
cause the function to fail. In most cases, it is preferable to use
MIME_ENCODING_BASE64 as the encoding method, with quoted-printable
encoding only used for legacy support.
If an unsupported encoding type is specified, this function will
return MIME_ERROR and the output text string will be empty. This
function cannot be used to decode uuencoded text.
Requirements
Minimum Desktop Platform: Windows 7 (Service Pack 1)
Minimum Server Platform: Windows Server 2008 R2 (Service Pack 1)
Header File: cstools10.h
Import Library: csmsgv10.lib
Unicode: Implemented as Unicode and ANSI versions.
See Also
MimeDecodeText,
MimeEncodeText,
MimeEncodeTextEx,
MimeGetMessageText,
MimeLocalizeText,
MimeSetMessageText
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