mblen—minimal multibyte length function #include <stdlib.h>
int mblen(const char *s, size_t n);
Description
When _MB_CAPABLE is not defined, this is a minimal ANSI-conforming
implementation of mblen. In this case, the
only “multi-byte character sequences” recognized are single bytes,
and thus 1 is returned unless s is the null pointer or
has a length of 0 or is the empty string.
When _MB_CAPABLE is defined, this routine calls _mbtowc_r to perform
the conversion, passing a state variable to allow state dependent
decoding. The result is based on the locale setting which may
be restricted to a defined set of locales.
Returns
This implementation of mblen returns 0 if
s is NULL or the empty string; it returns 1 if not _MB_CAPABLE or
the character is a single-byte character; it returns -1
if the multi-byte character is invalid; otherwise it returns
the number of bytes in the multibyte character.
Portability
mblen is required in the ANSI C standard. However, the precise
effects vary with the locale.
mblen requires no supporting OS subroutines.