Implementation status: to be implemented
wint_t btowc(int c);
The function transforms a single byte to a wide character.
c - a character to be transformed.
The behavior of this function is affected by the
LC_CTYPE category of the current locale.
The wide-character representation of that character c.
WEOF - if c is equal
EOF or if (unsigned char) c does not constitute a valid (one-byte) character in the initial shift state.
btowc() does not return
WEOF if c has a value in the range
No errors are defined.