7.12.3.2 The isfinite macro
Synopsis
#include <math.h>
int isfinite(real-floating x);
Description
The isfinite macro determines whether its argument has a finite value (zero, subnormal, or normal, and not infinite or NaN). First, an argument represented in a format wider than its semantic type is converted to its semantic type. Then determination is based on the type of the argument.
Returns
The isfinite macro returns a nonzero value if and only if its argument has a finite value.