DragonFly On-Line Manual Pages

MBRLEN(3)             DragonFly 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 <xlocale.h>

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

DESCRIPTION
     The mbrlen() and mbrlen_l() functions inspect at most n bytes pointed to
     by s to determine the number of bytes needed to complete the next
     multibyte character.

     The mbstate_t argument, ps, is used to keep track of the shift state.  If
     it is NULL, mbrlen() and mbrlen_l() use 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() and mbrlen_l() use their
     own static, internal mbstate_t object to keep track of the shift state.

     The mbrlen_l() function takes an explicit locale argument, whereas the
     mbrlen() function uses the current global or per-thread locale.

RETURN VALUES
     The mbrlen() and mbrlen_l() functions return:

     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()
             and mbrlen_l() return the number of bytes used to complete the
             multibyte character.

     (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
     character 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() and mbrlen_l() functions 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'').

DragonFly 3.7                  December 26, 2013                 DragonFly 3.7