Re: isnanl, printf, and non-IEEE values

[Ben Pfaff]

Rich Felker <address@hidden> writes:

> On Mon, Jun 18, 2012 at 10:21:34AM -0700, Ben Pfaff wrote:
>> Bruno Haible <address@hidden> writes:
>> 
>> > In theory you would be right that data should be validated at the 
>> > boundaries
>> > of the program, that is, when they are read from outside sources. But no
>> > program I know of does this for unconstrained floating-point numbers.
>> 
>> That's an interesting point.  GNU PSPP reads unconstrained
>> "double"s from SPSS data files without validating them[*], since
>
> This is not a problem. As long as you're assuming IEEE, all 64-bit
> patterns are valid long double values. The issue only occurs for long
> double, a type that's very different in both arithmetic properties and
> representation between systems. On typical systems, it has padding
> bits (which might or might not be required to be all-zero) as well as
> bit combinations that are completely invalid.

OK, thanks for the information.  Never mind, then.