mbrlen3
Get number of bytes in a character (restartable)
Usage
#include <wchar.h>
size_t
mbrlen(const char * restrict s, size_t n, mbstate_t * restrict ps);
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.
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.
Releases
56 releases since FreeBSD 5.0-RELEASE; the text changed 33 times.