mbsrtowcs - convert a multibyte string to a wide-character string
size_t mbsrtowcs(wchar_t *dest, const char **src,
size_t len, mbstate_t *ps);
is not NULL, the mbsrtowcs
() function converts the
multibyte string *src
to a wide-character string starting at
. At most len
wide characters are written to dest
The shift state *ps
is updated. The conversion is effectively performed
by repeatedly calling mbrtowc(dest, *src, n, ps)
positive number, as long as this call succeeds, and then incrementing
by one and *src
by the number of bytes consumed. The
conversion can stop for three reasons:
- An invalid multibyte sequence has been encountered. In this case,
*src is left pointing to the invalid multibyte sequence,
(size_t) -1 is returned, and errno is set to
- len non-L'\0' wide characters have been stored at dest. In
this case, *src is left pointing to the next multibyte sequence to
be converted, and the number of wide characters written to dest is
- The multibyte string has been completely converted, including the
terminating null wide character ('\0'), which has the side effect of
bringing back *ps to the initial state. In this case, *src
is set to NULL, and the number of wide characters written to dest,
excluding the terminating null wide character, is returned.
is NULL, len
is ignored, and the conversion proceeds as
above, except that the converted wide characters are not written out to
memory, and that no length limit exists.
In both of the above cases, if ps
is NULL, a static anonymous state known
only to the mbsrtowcs
() function is used instead.
The programmer must ensure that there is room for at least len
characters at dest
() function returns the number of wide characters that make
up the converted part of the wide-character string, not including the
terminating null wide character. If an invalid multibyte sequence was
encountered, (size_t) -1
is returned, and errno
For an explanation of the terms used in this section, see attributes
POSIX.1-2001, POSIX.1-2008, C99.
The behavior of mbsrtowcs
() depends on the LC_CTYPE
the current locale.
Passing NULL as ps
is not multithread safe.