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[There are a few questions on this but none of the answers are particularly definitive and several are out of date with the current C++ standard].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

If your question is "Can I convert this double to int without loss of information?" then I would do something simple like :

template 
bool CanConvert(U u)
{
  return U(T(u)) == u;
}

CanConvert(1.0) -- true
CanConvert(1.5) -- false
CanConvert(1e9) -- true
CanConvert(1e10)-- false