Re: A little unrelated but it's a question about C :)

[Alexandre Fayolle <Alexandre Fayolle logilab fr>]

On Mon, 5 Feb 2001, Marco Quezada wrote:

> Hi,
>
> I'm trying to debug a program and I need to have a printf statement that
> will get called when a float variable turns into NaN.
>
> I tried something like
>
> if(VARIABLE == NULL)
> {
>    printf("%d" , Called_Function_Id);
> }
> But the compiler doesn't like it. Is there a way to catch a NaN value
> like that?

math.h defines a bunch of useful functions:

 int isinf (double value); returns -1 if value is -infinite, +1 if
it is +infinite and 0 otherwise

 int isnan (double value); returns true if value is NaN, and 0
otherwise

 int finite (double value); returns true is value is numeric and finite,
and 0 otherwise.

Check the manpage for one of those three functions for more information.

Alexandre Fayolle
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