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

There is an std::isnan if you compiler supports c99 extensions, but I'm not sure if mingw does.

Here is a small function which should work if your compiler doesn't have the standard function:

bool custom_isnan(double var)
{
    volatile double d = var;
    return d != d;
}