What is going on with bitwise operators and integer promotion?

Question

I have a simple program. Notice that I use an unsigned fixed-width integer 1 byte in size.

#include 
#include 

        

Answer 1

I tested larger numbers and operator << always gives me positive numbers, while operator ~ always gives me negative numbers. I then used sizeof() and found...

Wrong, test it:

uint8_t v = 1;
for (int i=0; i<32; i++) cout << (v<

gives:

1
2
4
8
16
32
64
128
256
512
1024
2048
4096
8192
16384
32768
65536
131072
262144
524288
1048576
2097152
4194304
8388608
16777216
33554432
67108864
134217728
268435456
536870912
1073741824
-2147483648

uint8_t is an 8-bit long unsigned integer type, which can represent values in the range [0,255], as that range in included in the range of int it is promoted to int (not unsigned int). Promotion to int has precedence over promotion to unsigned.