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.

SEE ALSO

mblen(3), mbrtowc(3), multibyte(3)

STANDARDS

The mbrlen() function conforms to ISO/IEC 9899:1999 (“ISO C99”).