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MBSRTOWCS(3) Linux Programmer's Manual MBSRTOWCS(3)

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 NULL, 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  mbr-
     towc(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, 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 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 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.

ATTRIBUTES

     For   an   explanation   of   the  terms  used  in  this  section,  see
     attributes(7).

     +------------+---------------+------------------------------+
     |Interface   | Attribute     | Value                        |
     +------------+---------------+------------------------------+
     |mbsrtowcs() | Thread safety | MT-Unsafe race:mbsrtowcs/!ps |
     +------------+---------------+------------------------------+

CONFORMING TO

     POSIX.1-2001, POSIX.1-2008, C99.

NOTES

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

     Passing NULL as ps is not multithread safe.