mbsnrtowcs - convert a multibyte string to a wide-character string
#include <wchar.h>
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)):
mbsnrtowcs():
- Since glibc 2.10:
- _POSIX_C_SOURCE >= 200809L
- Before glibc 2.10:
- _GNU_SOURCE
The
mbsnrtowcs() function is like the
mbsrtowcs(3) function,
except that the number of bytes to be converted, starting at
*src, is
limited to at most
nms bytes.
If
dest is not NULL, the
mbsnrtowcs() function converts at most
nms bytes from the multibyte string
*src to a wide-character
string starting 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,
excluding the terminating null wide character, is returned.
According to POSIX.1, if the input buffer ends with an incomplete character, it
is unspecified whether conversion stops at the end of the previous character
(if any), or at the end of the input buffer. The glibc implementation adopts
the former behavior.
If
dest 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 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 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 set to
EILSEQ.
For an explanation of the terms used in this section, see
attributes(7).
| Interface |
Attribute |
Value |
| mbsnrtowcs () |
Thread safety |
MT-Unsafe race:mbsnrtowcs/!ps |
POSIX.1-2008.
The behavior of
mbsnrtowcs() depends on the
LC_CTYPE category of
the current locale.
Passing NULL as
ps is not multithread safe.
iconv(3),
mbrtowc(3)
mbsinit(3),
mbsrtowcs(3)