mbrlen3

Usage

Library

Standard C Library (libc, -lc)

Overview

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.

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

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.