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NAME

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

SYNOPSIS

       #include <wchar.h>

       size_t mbsrtowcs(wchar_t *dest, const char **src,
                         size_t len, mbstate_t *ps);

DESCRIPTION

       If dest is not a NULL pointer, the mbsrtowcs() function converts 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. 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 length limit exists.

       In  both  of the above cases, if ps is a NULL pointer, a static anonymous state only known
       to the mbsrtowcs() function is used instead.

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

RETURN VALUE

       The mbsrtowcs() 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

       C99.

NOTES

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

       Passing NULL as ps is not multithread safe.

SEE ALSO

       iconv(3), mbsnrtowcs(3), mbstowcs(3)

COLOPHON

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