size_t mbsnrtowcs(wchar_t *dest, const char **src,
size_t nms, size_t len, mbstate_t *ps);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
Since glibc 2.10:
_XOPEN_SOURCE >= 700 || _POSIX_C_SOURCE >= 200809L
Before glibc 2.10:
The mbsnrtowcs() function is like the mbsrtowcs(3) function, except
that the number of bytes to be converted, starting at *src, is limited
If dest is not NULL, the mbsnrtowcs() function converts at most nms
bytes from the multibyte string *src to a wide-character string start-
ing at dest. 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) where n is some positive
number, as long as this call succeeds, and then incrementing dest by
one and *src by the number of bytes consumed. The conversion can stop
for three reasons:
1. 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 EILSEQ.
2. The nms limit forces a stop, or 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 returned.
3. 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, exclud-
ing the terminating null wide character, is returned.
If dest is NULL, len is ignored, and the conversion proceeds as above,
except that the converted wide characters are not written out to mem-
ory, and that no destination length limit exists.
In both of the above cases, if ps is NULL, a static anonymous state
known only to the mbsnrtowcs() function is used instead.
The programmer must ensure that there is room for at least len wide
characters at dest.
The mbsnrtowcs() function returns the number of wide characters that
The behavior of mbsnrtowcs() depends on the LC_CTYPE category of the
Passing NULL as ps is not multithread safe.
iconv(3), mbrtowc(3) mbsinit(3), mbsrtowcs(3)
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