mbrtowc

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



NAME
       mbrtowc - convert a multibyte sequence to a wide character

SYNOPSIS
       #include <wchar.h>

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

DESCRIPTION
       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 multi-
       byte 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', 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  char-
       acter,  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, excepts 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 a NULL pointer, a static  anonymous
       state  only  known 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
       The mbrtowc function returns the number of bytes parsed from the multi-
       byte sequence starting at s, if a non-L'\0' wide character  was  recog-
       nized.   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.

CONFORMING TO
       ISO/ANSI C, UNIX98

SEE ALSO
       mbsrtowcs(3)

NOTES
       The behaviour of mbrtowc depends on the LC_CTYPE category of  the  cur-
       rent locale.



GNU                               2001-11-22                        MBRTOWC(3)