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mbrlen(3)                BSD Library Functions Manual                mbrlen(3)


NAME

     mbrlen, mbrlen_l -- get number of bytes in a character (restartable)


LIBRARY

     Standard C Library (libc, -lc)


SYNOPSIS

     #include <wchar.h>

     size_t
     mbrlen(const char *restrict s, size_t n, mbstate_t *restrict ps);

     #include <wchar.h>
     #include <xlocale.h>

     size_t
     mbrlen_l(const char *restrict s, size_t n, mbstate_t *restrict ps,
         locale_t loc);


DESCRIPTION

     The mbrlen() function inspects at most n bytes, pointed to by s, to
     determine the number of bytes needed to complete the next multibyte char-
     acter.

     The mbstate_t argument, ps, is used to keep track of the shift state.  If
     it is NULL, mbrlen() uses an internal, static mbstate_t object, which is
     initialized to the initial conversion state at program startup.

     It is equivalent to:

           mbrtowc(NULL, s, n, ps);

     Except that, when ps is a NULL pointer, mbrlen() uses its own static,
     internal mbstate_t object to keep track of the shift state.

     Although the mbrlen() function uses the current locale, the mbrlen_l()
     function may be passed a locale directly. See xlocale(3) for more infor-
     mation.


RETURN VALUES

     The mbrlen() functions returns:

     0       The next n or fewer bytes represent the null wide character
             (L'\0').

     >0      The next n or fewer bytes represent a valid character, mbrlen()
             returns the number of bytes used to complete the multibyte char-
             acter.

     (size_t)-2
             The next n contribute to, but do not complete, a valid multibyte
             character sequence, and all n bytes have been processed.

     (size_t)-1
             An encoding error has occurred.  The next n or fewer bytes do not
             contribute to a valid multibyte character.


EXAMPLES

     A function that calculates the number of characters in a multibyte char-
     acter string:

           size_t
           nchars(const char *s)
           {
                   size_t charlen, chars;
                   mbstate_t mbs;

                   chars = 0;
                   memset(&mbs, 0, sizeof(mbs));
                   while ((charlen = mbrlen(s, MB_CUR_MAX, &mbs)) != 0 &&
                       charlen != (size_t)-1 && charlen != (size_t)-2) {
                           s += charlen;
                           chars++;
                   }

                   return (chars);
           }


ERRORS

     The mbrlen() function will fail if:

     [EILSEQ]           An invalid multibyte sequence was detected.

     [EINVAL]           The conversion state is invalid.


SEE ALSO

     mblen(3), mbrtowc(3), multibyte(3), xlocale(3)


STANDARDS

     The mbrlen() function conforms to ISO/IEC 9899:1999 (``ISO C99'').

BSD                              April 7, 2004                             BSD

Mac OS X 10.5 - Generated Sun Oct 28 21:34:56 EDT 2007
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