int isnand (double dsrc);
int isnanf (float fsrc);
int finite (double dsrc);
fpclass_t fpclass (double dsrc);
int unordered (double dsrc1, double dsrc2);
int isnan (double dsrc);
isnanf is implemented as a macro included in the ieeefp.h header file.
fpclass returns the class that dsrc belongs to. The 10 possible classes are as follows:
finite returns true (1) if the argument dsrc is neither infinity nor NaN; otherwise it returns false (0).
unordered returns true (1) if one of its two arguments is unordered with respect to the other argument. This is equivalent to reporting whether either argument is NaN. If neither of the arguments is NaN, false (0) is returned.
None of these routines generates exceptions, even for signaling NaNs.