freebsd man page for mbrlen

MBRLEN(3)						   BSD Library Functions Manual 						 MBRLEN(3)

NAME
     mbrlen -- 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);

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 charac-
     ter.

     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.

RETURN VALUES
     The mbrlen() functions returns:

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

     >0      The next n or fewer bytes represent a valid character, mbrlen() returns 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() 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)

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

BSD
								   April 7, 2004							       BSD