The MultiByteToWideChar function maps a character string to a wide-character (Unicode) string. The character string mapped by this function is not necessarily from a multibyte character set.
int MultiByteToWideChar(
UINT CodePage, // code page
DWORD dwFlags, // character-type options
LPCSTR lpMultiByteStr, // address of string to map
int cchMultiByte, // number of bytes in string
LPWSTR lpWideCharStr, // address of wide-character buffer
int cchWideChar // size of buffer
);
Value | Meaning |
---|---|
CP_ACP | ANSI code page |
CP_MACCP | Macintosh code page |
CP_OEMCP | OEM code page |
CP_SYMBOL | Symbol code page (42) |
CP_THREAD_ACP | The current thread's ANSI code page |
CP_UTF7 | Translate using UTF-7 |
CP_UTF8 | Translate using UTF-8 |
Value | Meaning |
---|---|
MB_PRECOMPOSED | Always use precomposed characters — that is, characters in which a base character and a nonspacing character have a single character value. This is the default translation option. Cannot be used with MB_COMPOSITE. |
MB_COMPOSITE | Always use composite characters — that is, characters in which a base character and a nonspacing character have different character values. Cannot be used with MB_PRECOMPOSED. |
MB_ERR_INVALID_CHARS | If the function encounters an invalid input character, it fails and GetLastError returns ERROR_NO_UNICODE_TRANSLATION. |
MB_USEGLYPHCHARS | Use glyph characters instead of control characters. |
A composite character consists of a base character and a nonspacing character, each having different character values. A precomposed character has a single character value for a base/non-spacing character combination. In the character è, the e is the base character and the accent grave mark is the nonspacing character.
The function's default behavior is to translate to the precomposed form. If a precomposed form does not exist, the function attempts to translate to a composite form.
The flags MB_PRECOMPOSED and MB_COMPOSITE are mutually exclusive. The MB_USEGLYPHCHARS flag and the MB_ERR_INVALID_CHARS can be set regardless of the state of the other flags.
If the function succeeds, and cchWideChar is nonzero, the return value is the number of wide characters written to the buffer pointed to by lpWideCharStr.
If the function succeeds, and cchWideChar is zero, the return value is the required size, in wide characters, for a buffer that can receive the translated string.
If the function fails, the return value is zero. To get extended error information, call GetLastError. GetLastError may return one of the following error codes:
ERROR_INSUFFICIENT_BUFFER
ERROR_INVALID_FLAGS
ERROR_INVALID_PARAMETER
ERROR_NO_UNICODE_TRANSLATION
The lpMultiByteStr and lpWideCharStr pointers must not be the same. If they are the same, the function fails, and GetLastError returns the value ERROR_INVALID_PARAMETER.
The function fails if MB_ERR_INVALID_CHARS is set and it encounters an invalid character in the source string. An invalid character is one that would translate to the default character if MB_ERR_INVALID_CHARS was not set, but is not the default character in the source string, or when a lead byte is found in a string and there is no valid trail byte for DBCS strings. When an invalid character is found, and MB_ERR_INVALID_CHARS is set, the function returns 0 and sets GetLastError with the error ERROR_NO_UNICODE_TRANSLATION.
Windows CE: Windows CE does not support the CP_UTF7 and CP_UTF8 values for the CodePage parameter.
Windows NT: Requires version 3.1 or later.
Windows: Requires Windows 95 or later.
Windows CE: Requires version 1.0 or later.
Header: Declared in winnls.h.
Import Library: Use kernel32.lib.
Unicode and Character Sets Overview, Unicode and Character Set Functions, WideCharToMultiByte