interpret signed as unsigned

Question

I have a value like this:

int64_t s_val = SOME_SIGNED_VALUE;

How can I get a

uint64_t u_val

that has exactly

Answer 1

I agree static_cast is appropriate in this case, but no one has mentioned a very similar looking case where static_cast wouldn't preserve bits as might be expected.

char x = -1; // 255
unsigned int x2 = static_cast(x); // 4294967295
unsigned int x3 = static_cast(static_cast(x)); // 255

Watch out for sign extension when you are casting from a small signed value to a large unsigned value. Possibly other combinations are vulnerable too - I haven't thought it all the way through.