Bit manipulation right shift operator in C

Asked Jun 22 '21 at 07:11

Active Jun 22 '21 at 07:11

Viewed 27 times

#include<stdio.h>
int main()
{
    printf("%x\n", -1>>1);
    return 0;
}

Output:ffff

My Question is, we are shifting right one time , then we must get the output as 7fff

1111 1111 1111 1111--->ffff

0111 1111 1111 1111--->7fff

But why am I getting the output as ffff?

asked Jun 22 '21 at 07:11

Shyam Prasanna

1

Bitwise operations on signed values are always going to be tricky. – Some programmer dude Jun 22 '21 at 07:13
1

Because the value shifted is `signed`. To get your result, shift an `unsigned` variable. – Weather Vane Jun 22 '21 at 07:13
Also remember that `int` (the default type of `-1`) is commonly 32 bits wide. – Some programmer dude Jun 22 '21 at 07:14
Try `-1>>1` -> `0xffffffff >> 1` – Jabberwocky Jun 22 '21 at 07:15

0 Answers0