int main() { unsigned char a = -1; unsigned char b = -128; unsigned char c = 127; unsigned char d = b | a; // -1 (255) unsigned char e = b & a; // -128 (128) unsigned char f = b & c; // 0 (0) unsigned char g = b | c; // -1 (255) unsigned char h = -1 ^ -1; // 0 (0) unsigned char i = -1 ^ 0; // -1 (255) return d == 255 && e == 128 && f == 0 && g == 255 && h == 0 && i == 255; }