mbtowc - convert multi-byte character to wide character

Syntax	#include <stdlib.h> int mbtowc(wchar_t *pwc, const char *s, size_t n);
Description	mbtowc() converts a multi-byte character in s to the corresponding wchar_t value and stores this value in the area pwc. A maximum of n bytes in s are evaluated. The wchar_t value (type long) stored by mbtowc() in the area pwc corresponds to the value of the byte in s. No assignment takes place if: pwc or s is a null pointer, or n = 0.
Return val.	-1 0 1	if n = 0. if s is a null pointer or points to a null byte. in all other cases.
Notes	No characters consisting of multiple bytes are implemented in this version. Multi-byte characters always have a length of 1 byte, and wchar_t values are always of type long.
See also	mblen(), mbstowcs(), wcstombs(), wctomb(), stdlib.h.