Open Source Software

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
   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 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.

SEE ALSO

   iconv(3), mbrtowc(3), mbsinit(3), mbsnrtowcs(3), mbstowcs(3)

COLOPHON

   This  page  is  part of release 4.09 of the Linux man-pages project.  A
   description of the project, information about reporting bugs,  and  the
   latest     version     of     this    page,    can    be    found    at
   https://www.kernel.org/doc/man-pages/.



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