Checking if an object is a number in C#

Question

I\'d like to check if an object is a number so that .ToString() would result in a string containing digits and +,-,.

Answer 1

While writing my own object.IsNumeric() extension method based on Saul Dolgin's answer to this question I ran into a potential issue in that you will get an OverflowException if you try it with double.MaxValue or double.MinValue.

My "solution" was to combine the accepted answer from Noldorin with the one from Saul Dolgin and add a pattern matching switch before trying to parse anything (and use some C#7 goodness to tidy up a bit):

public static bool IsNumeric(this object obj)
{
    if (obj == null) return false;

    switch (obj)
    {
        case sbyte _: return true;
        case byte _: return true;
        case short _: return true;
        case ushort _: return true;
        case int _: return true;
        case uint _: return true;
        case long _: return true;
        case ulong _: return true;
        case float _: return true;
        case double _: return true;
        case decimal _: return true;
    }

    string s = Convert.ToString(obj, CultureInfo.InvariantCulture);

    return double.TryParse(s, NumberStyles.Any, NumberFormatInfo.InvariantInfo, out double _);
}