# V6038. Comparison with 'double.NaN' is meaningless. Use 'double.isNaN()' method instead.

The analyzer detected that a variable of type float or double is compared with a Float.NaN or Double.NaN value. As stated in the documentation (15.21.1), if two Double.NaN values are tested for equality by using the '==' operator, the result is false. So, no matter what value of 'double' type is compared with Double.NaN, the result is always false.

Consider the following example:

    void Func(double d) {
      if (d == Double.NaN) {
        ....
      }
    }

It's incorrect to test the value for NaN using operators '==' and '!= '. Instead, method Float.isNaN() or Double.isNaN() should be used. The fixed version of the code:

    void Func(double d) {
      if (Double.isNaN(d)) {
        ....
      }
    }

This diagnostic is classified as:

CWE-570 CWE-571 CERT-NUM07-J