> That sure doesn't sound like numbers are 64 bit floats, according to the spec. It can't be 64 bit floats, because they are represented as decimal numbers, no

> That sure doesn't sound like numbers are 64 bit floats, according to the spec. It can't be 64 bit floats, because they are represented as decimal numbers, not binary. You will be surprised to also hear that most base conversion algorithms used are not exact, and so different implementations might give different results in the LSB(s) for some numbers for performance reasons. Here practicality prevails, because making the standard stricter would make its implementation much harder in many environments. And for many applications it isn't a problem. I am sure btw that most file formats that use decimal representations for floating point numbers have this property, otherwise exact base conversion would be more prominently accessible in more programming languages. I have some hope that this will change in the future, as exact base conversion (lossless round trip) will gain momentum now that it landed in standard C++. Once most common programming languages have this feature, there isn't a big reason to not modify the standard anymore to enforce lossless round-trip.