Checking if a double (or float) is NaN in C++

Question

Is there an isnan() function?

PS.: I\'m in MinGW (if that makes a difference).

I had this solved by using isnan() from , which doe

Answer 1

This detects infinity and also NaN in Visual Studio by checking it is within double limits:

//#include 
double x, y = -1.1; x = sqrt(y);
if (x >= DBL_MIN && x <= DBL_MAX )
    cout << "DETECTOR-2 of errors FAILS" << endl;
else
    cout << "DETECTOR-2 of errors OK" << endl;