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NAME

       mbsnrtowcs - convert a multibyte string to a wide-character string

SYNOPSIS

       #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:
               _XOPEN_SOURCE >= 700 || _POSIX_C_SOURCE >= 200809L
           Before glibc 2.10:
               _GNU_SOURCE

DESCRIPTION

       The  mbsnrtowcs()  function  is  like the mbsrtowcs(3) function, except that the number of
       bytes to be converted, starting at *src, is limited to nms.

       If dest is not a NULL pointer, 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.

       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 a NULL pointer, a static anonymous state only known
       to the mbsnrtowcs function is used instead.

       The programmer must ensure that there is room for at least len wide characters at dest.

RETURN VALUE

       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.

CONFORMING TO

       POSIX.1-2008.

NOTES

       The behavior of mbsnrtowcs() depends on the LC_CTYPE category of the current locale.

       Passing NULL as ps is not multithread safe.

SEE ALSO

       iconv(3), mbsrtowcs(3)

COLOPHON

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