Best way of checking if a floating point is an integer

Question

[There are a few questions on this but none of the answers are particularly definitive and several are out of date with the current C++ standard].

My research shows

Answer 1

Some other options to consider (different compilers / libraries may produce different intrinsic sequences for these tests and be faster/slower):

bool is_int(float f) { return floor(f) == f; }

This is in addition to the tests for overflow you have...

If you are looking to really optimize, you could try the following (works for positive floats, not thoroughly tested): This assumes IEEE 32-bit floats, which are not mandated by the C++ standard AFAIK.

bool is_int(float f)
{
    const float nf = f + float(1 << 23);
    const float bf = nf - float(1 << 23);
    return f == bf;
}