Best practices for circular shift (rotate) operations in C++

Question

Left and right shift operators (<< and >>) are already available in C++. However, I couldn\'t find out how I could perform circular shift or rotate operations.

Answer 1

In details you can apply the following logic.

If Bit Pattern is 33602 in Integer

1000 0011 0100 0010

and you need to Roll over with 2 right shifs then: first make a copy of bit pattern and then left shift it: Length - RightShift i.e. length is 16 right shift value is 2 16 - 2 = 14

After 14 times left shifting you get.

1000 0000 0000 0000

Now right shift the value 33602, 2 times as required. You get

0010 0000 1101 0000

Now take an OR between 14 time left shifted value and 2 times right shifted value.

1000 0000 0000 0000
0010 0000 1101 0000
===================
1010 0000 1101 0000
===================

And you get your shifted rollover value. Remember bit wise operations are faster and this don't even required any loop.