bitwise stuff

[slatk3y]

Hello, I have a question about bitwise operators, especially shifting.
Suppose we have:

#include <iostream>

using namespace std;

int main() {
    unsigned i = 2;
    i<<=2;
    cout << i << endl;
}

unsigned i = 2 in binary is 0.......00010, if we shift 2 bits to the left we will get 8, which is 0.......01000.

How can we print out or change bits using shift opertars(<<, >>)?

Thanks in advance

[John A]

Perhaps take a look at bitset ?

Or you can do it "manually":
http://faq.cprogramming.com/cgi-bin/smartfaq.cgi?answer=1074727388&id=1073086407

Keep in mind that signed/unsigned, big endian/little endian issues could affect your implementation's portability.

[slatk3y]

ok, so that make sense.
Thanks.

I have another question now. I am trying to set a bit in unsigned, that is what I am doing:

#include <iostream>

using namespace std;

int main(){
    unsigned i = 0;
    unsigned index = 1;
    i >> (31 - index) |= 1;
}

But I am getting this error:
invalid lvalue in assignment at line 8.

Can't figure that out.

Thanks for helping.

[MrSpigot]

ok, so that make sense. Thanks.

I have another question now. I am trying to set a bit in unsigned, that is what I am doing:

#include <iostream>

using namespace std;

int main(){
    unsigned i = 0;
    unsigned index = 1;
    i >> (31 - index) |= 1;
}

But I am getting this error: invalid lvalue in assignment at line 8.

Can't figure that out.

Thanks for helping.

The left hand side of your expression does not compile to a memory address, which is necessary for the assignment to occur.
Set a bit like this:
i |= (1 << index);

[slatk3y]

Thanks for help guys, that works