Does Double.Parse(“NaN”) parse correctly?

Question

Does the C# Double parse "NaN" correctly, ie. does Double.Parse("NaN").ToString() == "NaN" ?

Answer 1

Try it:

PS> $ic = [Globalization.CultureInfo]::InvariantCulture
PS> [double]::parse('NaN', $ic).ToString($ic)
NaN

However, parsing and output of this string is locale-dependent, so either make sure you're always passing a culture or don't make too many assumptions about the format.

Answer 2

var d = Double.Parse("NaN");
Console.WriteLine(d); // prints "NaN"

I'm running under the en-US locale. As Joey notes, be careful around this. I got the same results when I specified the invariant culture (as one often should in these circumstances):

var d = Double.Parse("NaN", CultureInfo.InvariantCulture);
Console.WriteLine(d.ToString(CultureInfo.InvariantCulture)); // prints "NaN"