Does NumberBox.Value NaN not equal to double.NaN?

Question

When I use NumberBox (WinUI2), I have trouble as follows:

if (NumberBox.Value == double.NaN) // It keeps false.
{
     // Some action codes.
}

Is there any bug about this equation?

I would appreciate it if anyone could solve this problem.

Answer 1

Hello,

Welcome to Microsoft Q&A!

The reason for this behavior is the Double.NaN itself. Based on the document- Double.NaN Field, it is mentioned that: The Equality operator considers two NaN values to be unequal to one another. In general, Double operators cannot be used to compare Double.NaN with other Double values. And it is suggested to use the IsNaN method.

Like:

if (double.IsNaN(NumberBox.Value)) 
{
    // Some action codes.
}

Thank you.

---

If the answer is the right solution, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Answer 2

The equality check between NumberBox.Value and double.NaN will always return false. This is because double.NaN is not equal to any value, including itself. Instead, you can use the double.IsNaN() method to check if a value is NaN. Here's an example:

if (double.IsNaN(NumberBox.Value))
{
    // Some action codes.
}

This should solve the problem you're experiencing.

---

References:

• Number.IsNaN - Syntax
• Number.IsNaN - About
• Number.NaN - About
• NumberBox - UWP and WinUI 2