Unexepected behavior from multiple bitwise shifts on the same line [duplicate]

Answer 1

Yes, the result of the first shift is signed. signed int specifically. Check out the rules for the "integer promotions" in the C spec:

If an int can represent all values of the original type ... the value is converted to an int...

So, since your int - usually a range of [-2³¹, 2³¹) - can represent all the values of unsigned char - usually [0, 255] - it's converted to int, and the << and >> take place on the resulting values.