NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ATTRIBUTES | CONFORMING TO | NOTES | SEE ALSO | COLOPHON

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

NAME         top

       mbrtowc - convert a multibyte sequence to a wide character

SYNOPSIS         top

       #include <wchar.h>

       size_t mbrtowc(wchar_t *pwc, const char *s, size_t n, mbstate_t *ps);

DESCRIPTION         top

       The main case for this function is when s is not NULL and pwc is not
       NULL.  In this case, the mbrtowc() function inspects at most n bytes
       of the multibyte string starting at s, extracts the next complete
       multibyte character, converts it to a wide character and stores it at
       *pwc.  It updates the shift state *ps.  If the converted wide
       character is not L'\0' (the null wide character), it returns the
       number of bytes that were consumed from s.  If the converted wide
       character is L'\0', it resets the shift state *ps to the initial
       state and returns 0.

       If the n bytes starting at s do not contain a complete multibyte
       character, mbrtowc() returns (size_t) -2.  This can happen even if n
       >= MB_CUR_MAX, if the multibyte string contains redundant shift
       sequences.

       If the multibyte string starting at s contains an invalid multibyte
       sequence before the next complete character, mbrtowc() returns
       (size_t) -1 and sets errno to EILSEQ.  In this case, the effects on
       *ps are undefined.

       A different case is when s is not NULL but pwc is NULL.  In this
       case, the mbrtowc() function behaves as above, except that it does
       not store the converted wide character in memory.

       A third case is when s is NULL.  In this case, pwc and n are ignored.
       If the conversion state represented by *ps denotes an incomplete
       multibyte character conversion, the mbrtowc() function returns
       (size_t) -1, sets errno to EILSEQ, and leaves *ps in an undefined
       state.  Otherwise, the mbrtowc() function puts *ps in the initial
       state and returns 0.

       In all of the above cases, if ps is NULL, a static anonymous state
       known only to the mbrtowc() function is used instead.  Otherwise, *ps
       must be a valid mbstate_t object.  An mbstate_t object a can be
       initialized to the initial state by zeroing it, for example using

           memset(&a, 0, sizeof(a));

RETURN VALUE         top

       The mbrtowc() function returns the number of bytes parsed from the
       multibyte sequence starting at s, if a non-L'\0' wide character was
       recognized.  It returns 0, if a L'\0' wide character was recognized.
       It returns (size_t) -1 and sets errno to EILSEQ, if an invalid
       multibyte sequence was encountered.  It returns (size_t) -2 if it
       couldn't parse a complete multibyte character, meaning that n should
       be increased.

ATTRIBUTES         top

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

       ┌──────────┬───────────────┬────────────────────────────┐
       │Interface Attribute     Value                      │
       ├──────────┼───────────────┼────────────────────────────┤
       │mbrtowc() │ Thread safety │ MT-Unsafe race:mbrtowc/!ps │
       └──────────┴───────────────┴────────────────────────────┘

CONFORMING TO         top

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

NOTES         top

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

SEE ALSO         top

       mbsinit(3), mbsrtowcs(3)

COLOPHON         top

       This page is part of release 4.07 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/.

GNU                              2015-08-08                       MBRTOWC(3)