MBRLEN(3)

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

LIBRARY
libc

SYNOPSIS
#include <wchar.h>
size_t
mbrlen(const char * restrict s, size_t n, mbstate_t * restrict ps);

DESCRIPTION
The mbrlen() function determines the number of bytes constituting the multibyte character sequence pointed to by s, examining at most n bytes.

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.

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 first n or fewer bytes of s represent the null wide character (L'\0').

>0  The first n or fewer bytes of s represent a valid character, mbrtowc() returns the length (in bytes) of the multibyte sequence.

(size_t)-2
    The first n bytes of s are an incomplete multibyte sequence.

(size_t)-1
    The byte sequence pointed to by s is an invalid multibyte sequence.

EXAMPLES
A function which 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.

SEE ALSO
mblen(3), mbrtowc(3)

STANDARDS
The mbrlen() function conforms to isoC-99.

BUGS
The current implementation does not support shift states.