Date: 18 Mar 2003 15:54:21 -0000 Message-ID: <20030318155421.8252.qmail@tyr.diku.dk> From: Morten Welinder To: rudd AT cyberoptics DOT com cc: djgpp-workers AT delorie DOT com Subject: isnan Reply-To: djgpp-workers AT delorie DOT com You use the fact that sizeof (float) != sizeof (double). #define isnan(x) (sizeof (x) == sizeof (float) ? isnanf (x) : isnand (x)) -- possibly extended to handle long double also. (And note that even thought "x" occurs three times, it will be evaluated exactly once.) FYI, Solaris just uses a function is double arg. Morten