The signed integer is int, because there are positive and negative points, so the first bit of 16 means positive and negative, 0 means positive, and 1 means negative.

So it can be expressed in the range of-32768 ~+32767 (-2e15 ~ 2e15-1).

Unsigned integer is defined as unsigned int, because the first bit doesn't mean positive or negative, and it is all positive, so 16 bits are all significant bits, so the value range is 0 ~ 65535 (0 ~ 2E 16- 1).