MBRLEN(3) | FreeBSD 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 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.
STANDARDS
The mbrlen() function conforms to ISO/IEC 9899:1999 (“ISO C99”).April 7, 2004 | FreeBSD |