C - Serialization of the floating point numbers (floats, doubles)

Question

How to convert a floating point number into a sequence of bytes so that it can be persisted in a file? Such algorithm must be fast and highly portable. It must allow also th

Answer 1

What do you mean, "portable"?

For portability, remember to keep the numbers within the limits defined in the Standard: use a single number outside these limits, and there goes all portability down the drain.

double planck_time = 5.39124E-44; /* second */

---

5.2.4.2.2 Characteristics of floating types

[...]
10   The values given in the following list shall be replaced by constant
     expressions with implementation-defined values [...]
11   The values given in the following list shall be replaced by constant
     expressions with implementation-defined values [...]
12   The values given in the following list shall be replaced by constant
     expressions with implementation-defined (positive) values [...]
[...]

Note the implementation-defined in all these clauses.