IdnToUnicode function (winnls.h)
Converts the Punycode form of an internationalized domain name (IDN) or another internationalized label to the normal Unicode UTF-16 encoding syntax.
Syntax
int IdnToUnicode(
[in] DWORD dwFlags,
[in] LPCWSTR lpASCIICharStr,
[in] int cchASCIIChar,
[out, optional] LPWSTR lpUnicodeCharStr,
[in] int cchUnicodeChar
);
Parameters
[in] dwFlags
Flags specifying conversion options. For detailed definitions, see the dwFlags parameter of IdnToAscii.
[in] lpASCIICharStr
Pointer to a string representing the Punycode encoding of an IDN or another internationalized label. This string must consist only of ASCII characters, and can include Punycode-encoded Unicode. The function decodes Punycode values to their UTF-16 values.
[in] cchASCIIChar
Count of characters in the input string indicated by lpASCIICharStr.
[out, optional] lpUnicodeCharStr
Pointer to a buffer that receives a normal Unicode UTF-16 encoding equivalent to the Punycode value of the input string. Alternatively, the function can retrieve NULL for this parameter, if cchUnicodeChar set to 0. In this case, the function returns the size required for this buffer.
[in] cchUnicodeChar
Size, in characters, of the buffer indicated by lpUnicodeCharStr. The application can set the size to 0 to retrieve NULL in lpUnicodeCharStr and have the function return the required buffer size.
Return value
Returns the number of characters retrieved in lpUnicodeCharStr if successful. The retrieved string is null-terminated only if the input string is null-terminated.
If the function succeeds and the value of cchUnicodeChar is 0, the function returns the required size, in characters including a terminating null character if it was part of the input buffer.
The function returns 0 if it does not succeed. To get extended error information, the application can call GetLastError, which can return one of the following error codes:
- ERROR_INSUFFICIENT_BUFFER. A supplied buffer size was not large enough, or it was incorrectly set to NULL.
- ERROR_INVALID_FLAGS. The values supplied for flags were not valid.
- ERROR_INVALID_NAME. An invalid name was supplied to the function. Note that this error code catches all syntax errors.
- ERROR_INVALID_PARAMETER. Any of the parameter values was invalid.
- ERROR_NO_UNICODE_TRANSLATION. Invalid Unicode was found in a string.
Remarks
See Remarks for IdnToAscii.
Requirements
Requirement | Value |
---|---|
Minimum supported client | Windows Vista [desktop apps | UWP apps] |
Minimum supported server | Windows Server 2008 [desktop apps | UWP apps] |
Target Platform | Windows |
Header | winnls.h (include Windows.h) |
Library | Normaliz.lib |
DLL | Normaliz.dll |
Redistributable | Microsoft Internationalized Domain Name (IDN) Mitigation APIs onWindows XP with SP2 and later, orWindows Server 2003 with SP1 |