mbsrtowcs(3) — Linux manual page


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

NAME         top

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

SYNOPSIS         top

       #include <wchar.h>

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

DESCRIPTION         top

       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

       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

       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         top

       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         top

       For an explanation of the terms used in this section, see

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

CONFORMING TO         top

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

NOTES         top

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

       Passing NULL as ps is not multithread safe.

SEE ALSO         top

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

COLOPHON         top

       This page is part of release 5.09 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

GNU                              2019-03-06                     MBSRTOWCS(3)

Pages that refer to this page: mbrtowc(3)mbsinit(3)mbsnrtowcs(3)mbstowcs(3)unicode(7)utf-8(7)utf8(7)UTF-8(7)