Whatever data-type you choose, ~077
will set the rightmost 6 bits to 0
and all others to 1
.
Assuming 16-bit int
s and 32-bit long
s, there are 4 cases:
Case 1
unsigned int x = 077; // x = 0000 0000 0011 1111
x = ~x; // x = 1111 1111 1100 0000
unsigned long y = ~x; // y = 0000 0000 0000 0000 1111 1111 1100 0000
Case 2
unsigned int x = 077; // x = 0000 0000 0011 1111
x = ~x; // x = 1111 1111 1100 0000
long y = ~x; // y = 0000 0000 0000 0000 1111 1111 1100 0000
Case 3
int x = 077; // x = 0000 0000 0011 1111
x = ~x; // x = 1111 1111 1100 0000
unsigned long y = ~x; // y = 1111 1111 1111 1111 1111 1111 1100 0000
Case 4
int x = 077; // x = 0000 0000 0011 1111
x = ~x; // x = 1111 1111 1100 0000
long y = ~x; // y = 1111 1111 1111 1111 1111 1111 1100 0000
See code here. This means the sign extension is done when the source is signed
. When the source is unsigned
, sign bit is not extended and the left bits are set to 0
.