The behavior of the multibyte functions are affected by the
LC_CTYPE in the location
int mblen(const char *str
Returns the length of a multibyte character pointed to by the
argument str. At most n bytes will be examined.
If str is a null pointer, then zero is returned if
multibyte characters are not state-dependent (shift state).
Otherwise a nonzero value is returned if multibyte character are
If str is not null, then the number of bytes that are
contained in the multibyte character pointed to by str
are returned. Zero is returned if str points to a null
character. A value of -1 is returned if str does not
point to a valid multibyte character.