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 inspects 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() 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').

>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 isoC-99.