int mbtowc(whcar_t *pwc
const char *str
Examines the multibyte character pointed to by the argument
str. The value is converted and stored in the argument
pwc if pwc is not null. It scans at most n
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.