Most efficient standard-compliant way of reinterpreting int as float

Question

Assume I have guarantees that float is IEEE 754 binary32. Given a bit pattern that corresponds to a valid float, stored in std::uint32_t, how does

Answer 1

If the bitpattern in the integer variable is the same as a valid float value, then union is probably the best and most compliant way to go. And it's actually legal if you read the specification (don't remember the section at the moment).