nantest
nantest is a simple demo program that shows how to test for calculations resulting in Not a Number (nan), positive infinity (inf), and negative infinity (-inf) in c++. nantest uses the finite() function call. sqrt(-1.0) would result in nan. 1/0 would result in inf. -1/0 would result in -inf.
//nantest.cpp
//simple program to demonstrate testing of non-finite values
//built and tested with
//g++ -o nantest nantest.cpp
//on Red Hat Linux gcc 3.2.2 kernel 2.4.22 on i686
#include <iostream>
using namespace std;
int main(){
float denominator = 0;
float plusinfinity = 1/denominator;
float minusinfinity = -1/denominator;
float nanumber = sqrt(-1.0);
cout << "denominator: " << denominator;
if(!finite(denominator))
cout << " is not finite.\n";
else
cout << " is finite.\n";
cout << "plusinfinity: " << plusinfinity;
if(!finite(plusinfinity))
cout << " is not finite.\n";
else
cout << " is finite.\n";
cout << "minusinfinity: " << minusinfinity;
if(!finite(minusinfinity))
cout << " is not finite.\n";
else
cout << " is finite.\n";
cout << "nanumber: " << nanumber;
if(!finite(nanumber))
cout << " is not finite.\n";
else
cout << " is finite.\n";
return 0;
}//end main
