NaN

I have been lately involved a lot with the recruitment process for my current employer. It has in fact provided me a good platform to learn and hone my skills to the maximum. Anyways, that is not a point of discussion for now.

In my role as an interviewer, I come across many candidates who, when asked, would rate them very highly on Core Java skills. It is not as if a person cannot be very strong with core computing skills, but it is understanding of basic concepts of computing. Take this: One of my favorite startup questions in such a scenario is,

What would be the result of compilation/execution of the following code snippet?

public class NaN {
	public static void main(String[] args) {
		double d = 2.0 / 0.0;
		System.out.println(d);
	}
}

What’s the answer: The code will not compile or will it throw a DivideByZero error? Both are wrong. The code compiles fine and the output is,

Infinity

Let’s check another code snippet,

public class NaN {
	public static void main(String[] args) {
		double d = 0.0 / 0.0;
		System.out.println(d);
	}
}

The output in this case is,

NaN

Surprising! Pick up any JAVA book and the first thing they explain is the concept of NaN, yet, still most of us don’t remember it after a few months.

NaN as defined by Wikipedia, is a value or symbol that is usually produced as the result of an operation on invalid input operands, especially in floating-point calculations.

Time to revise the concepts :)