Question

I have UINT64 variable. In start it is initialized to 0xF. Now I want this to change on runtime depending on some input. Its value will increase on runtime. But what I want is that it should change from F to FF, from FF to FFF, one F should be appended to it.

Now here is my code.

UINT64 mapFileSize = 0xF;
while (mapFileSize < someUserInput)
    // add one F to mapFileSize;

What should I write there. I am trying left shift operator but it is not working fine.

mapFileSize <<= 1;

I am doing this but this does not give me desired result.

Answer 1

A more succinct way of doing it:

mapFileSize |= (mapFileSize << 4);

Or if you can’t guarantee that the original value always ends in 0xf:

mapFileSize = (mapFileSize << 4) | 0x0f;