header file: math.h
int finite(double x);
int finitef(float x);
_finite returns a nonzero value if its argument x is not
infinite; that is, if -INF < x < +INF. It returns 0 if the
argument is infinite or a NAN.
The Windows _finite() function performs in the same manner as
the Unix finite() function working with a double type. There is not
a matching Windows function for the Unix finitef() but it can
handled with a cast as shown in the example section.
Example of Use in Windows
#include <float.h>
double mydouble;
float myfloat;
int answer1, answer2;
answer1 = _finite(mynum); /* was finite() */
answer2 = _finite((double)myfloat); /* was finitef() */