netbsd man page for mblen

MBLEN(3)						   BSD Library Functions Manual 						  MBLEN(3)

NAME
     mblen -- get number of bytes in a multibyte character

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <stdlib.h>

     int
     mblen(const char *s, size_t n);

DESCRIPTION
     The mblen() function usually determines the number of bytes in a multibyte character pointed to by s and returns it.  This function shall
     only examine max n bytes of the array beginning from s.

     In state-dependent encodings, s may point the special sequence bytes to change the shift-state.  Although such sequence bytes corresponds to
     no individual wide-character code, the mblen() changes the own state by them and treats them as if they are a part of the subsequent multi-
     byte character.

     Unlike mbrlen(3), the first n bytes pointed to by s need to form an entire multibyte character.  Otherwise, this function causes an error.

     mblen() is equivalent to the following call, except the internal state of the mbtowc(3) function is not affected:

	   mbtowc(NULL, s, n);

     Calling any other functions in Standard C Library (libc, -lc) never changes the internal state of mblen(), except for calling setlocale(3)
     with the LC_CTYPE category changed to that of the current locale.	Such setlocale(3) calls cause the internal state of this function to be
     indeterminate.

     The behaviour of mblen() is affected by the LC_CTYPE category of the current locale.

     These are the special cases:

     s == NULL	 mblen() initializes its own internal state to an initial state, and determines whether the current encoding is state-dependent.
		 This function returns 0 if the encoding is state-independent, otherwise non-zero.

     n == 0	 In this case, the first n bytes of the array pointed to by s never form a complete character.	Thus, mblen() always fails.

RETURN VALUES
     Normally, mblen() returns:

     0		 s points to a nul byte ('').

     positive	 The value returned is a number of bytes for the valid multibyte character pointed to by s.  There are no cases that this value is
		 greater than n or the value of the MB_CUR_MAX macro.

     -1 	 s points to an invalid or incomplete multibyte character.  The mblen() also sets errno to indicate the error.

     When s is equal to NULL, the mblen() returns:

     0		 The current encoding is state-independent.

     non-zero	 The current encoding is state-dependent.

ERRORS
     mblen() may cause an error in the following case:

     [EILSEQ]		s points to an invalid or incomplete multibyte character.

SEE ALSO
     mbrlen(3), mbtowc(3), setlocale(3)

STANDARDS
     The mblen() function conforms to ANSI X3.159-1989 (``ANSI C89'').

BSD
								 February 3, 2002							       BSD