Portability of binary serialization of double/float type in C++

Question

The C++ standard does not discuss the underlying layout of float and double types, only the range of values they should represent. (This is also true for signed types, is i

Answer 1

What's wrong with a human readable format.

It has a couple of advantages over binary:

• It's readable
• It's portable
• It makes support really easy
  (as you can ask the user to look at it in their favorite editor even word)
• It's easy to fix
  (or adjust files manually in error situations)

Disadvantage:

• It's not compact
  If this a real problem you can always zip it.
• It may be slightly slower to extract/generate
  Note a binary format probably needs to be normalized as well (see htonl())

To output a double at full precision:

double v = 2.20;
std::cout << std::setprecision(std::numeric_limits::digits) << v;

OK. I am not convinced that is exactly precise. It may lose precision.