Question

I was just wondering if there was a way to bit shift a number “in place”?
I’ve googled exactly that, and I can’t find anything that pertains to what I want to do.
Say I have the number 0b01001101, and I want to shift it twice to the right “in place”, appending any numbers that fall off to the beginning. So it would look like 0b01010011.
Is there any function in c++ that would allow me to bit shift left or right like that?

Answer 1

You want to implement a rotational shift

Here’s a templatized version that should work with all types of ints (including shorts, chars, ints, and unsigned/signed alike).

template<class T>
T rotate_shift_right(T x, int shift)
{
    if ((shift > 0) && (shift < (sizeof(x)*8)))
    {
        x = ((unsigned)x >> shift) | (x << (sizeof(x) * 8 - shift));
    }
    return x;
}

template<class T>
T rotate_shift_left(T x, int shift)
{
    if ((shift > 0) && (shift < (sizeof(x)*8)))
    {
        x = (x << shift) | (((unsigned)x) >> (sizeof(x) * 8 - shift));
    }
    return x;
}