How to get the bit removed from the bitwise right shift in c#

Question

I have a int number And I have to shift it to the right a couple of times.

x   = 27 = 11011
x>>1= 13 = 1101
x>>2=  6 = 110
x>>3=  3 = 11

I would like to get the value bit value that has been removed. I would have to get: 1, 1, 0

How can I get the removed value

Just as a matter of interest, what are you doing with those bits after you've determined them? If you're combining them again in some way, there might be a more efficient way of doing the entire operation. — Matthew Watson, Jun 03 '13 at 13:22

score 7 · Answer 1 · answered Jun 03 '13 at 13:10

7

(x & 1) gives you the value of the least significant bit. You should calculate it before you shift.

answered Jun 03 '13 at 13:10

Mark Byers

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Mehmet Ataş · Accepted Answer · 2013-06-03T13:53:21.037

6

For least significant bit you can use x & 1 before each shifting. If you want to get a custom bit at any time without changing the value, you can use below method.

    private static int GetNthBit(int x, int n)
    {
        return (x >> n) & 1;
    }

edited Jun 03 '13 at 13:53

answered Jun 03 '13 at 13:13

Mehmet Ataş

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nice, but why not just `(x >> n) & 1`? – Eren Ersönmez Jun 03 '13 at 13:30
You are right! That was the first came up to my mind, I updated (: – Mehmet Ataş Jun 03 '13 at 13:52

Steve · Answer 3 · 2013-06-03T13:16:17.903

1

Just test the first bit before removing it

int b = x & 1;

See MSDN reference on & operator

edited Jun 03 '13 at 13:16

answered Jun 03 '13 at 13:10

Steve

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How to get the bit removed from the bitwise right shift in c#

3 Answers3