What is the C# equivalent of NaN or IsNumeric?

Question

What is the most efficient way of testing an input string whether it contains a numeric value (or conversely Not A Number)? I guess I can use Double.Parse or a

Answer 1

I know this has been answered in many different ways, with extensions and lambda examples, but a combination of both for the simplest solution.

public static bool IsNumeric(this String s)
{
    return s.All(Char.IsDigit);
}

or if you are using Visual Studio 2015 (C# 6.0 or greater) then

public static bool IsNumeric(this String s) => s.All(Char.IsDigit);

Awesome C#6 on one line. Of course this is limited because it just tests for only numeric characters.

To use, just have a string and call the method on it, such as:

bool IsaNumber = "123456".IsNumeric();