NaN and inf literal constants g++

From: Jon Wilson (jsw_at_fnal.gov)
Date: 12/31/04 

Date: Fri, 31 Dec 2004 02:41:41 GMT

How do I write Not A Number or +/- infinity (floating point values) as
literal constants (I'm using g++)?

I have a function that returns float, and I need a flag value, and for
various reasons one of NaN, +/-inf would be most convenient. But how do
I tell my function to return one of these? The best I can come up with
so far is

float foo()
{
        if(bar)
                return (2 + 2);
        else
                return (0.0 / 0.0);
}

Which works, ( (0.0 / 0.0) == NaN, or (1.0 / 0.0) == inf ), but g++
gives me a divide-by-zero warning when I compile.

Regards,
Jon

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