negative integers in binary

Question

 5 (decimal) in binary  00000101
-5 (two's complement) in binary 11111011

but 11111011 is also 251 (decimal)!

How does computer discern one from another?? How does it know whether it's -5 or 251??

it's THE SAME 11111011

Thanks in advance!!

Answer 1

Signed bytes have a maximum of 127.

Unsigned bytes cannot be negative.

The compiler knows whether the variable holding that value is of signed or unsigend type, and treats it appropriately.