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 *restrict dest, const char **restrict src,
                        size_t len, mbstate_t *restrict 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 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         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 5.13 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                            2021-03-22                   MBSRTOWCS(3)

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