Chris Evans

I came across a small issue the other day that I thought was interesting enough to make a post about. One of the methods I was interfacing with that returned a float would occasionally return a value of NaN (depending on the input), whereas I always wanted to use a numeric value.

To get around this I used the following snippet:

if (Float.isNaN(f))
{
    f = 0.0f;
}

But what’s interesting about this problem is that you can’t store a float valued as NaN in your class to compare against the other values by using == because, and I quote from a StackOverflow answer, “Java implements the IEEE-754 floating point standard which guarantees that any comparison against NaN will return false (except != which returns true)”.

This gives rise to the brilliant alternative which is to compare a float to itself! If it returns false, then you know it’s NaN.

if (f != f)
{
    // It's NaN.
}

While I’d be reluctant to actually use it due to lack of intuitiveness, little tricks like this are really interesting.