Sample.cs

using System;
using System.Globalization;

public static class DoubleClass
{
  public static bool CanBeDouble(string numericStr, out double value)
  {
    return double.TryParse(numericStr, NumberStyles.Float, CultureInfo.InvariantCulture, out value);
  }
}

public class Program
{
  static void Main(string[] args)
  {
    string numStr = "-119.4878";
    // string numStr = "-119.48781";

    if (DoubleClass.CanBeDouble(numStr, out double value))
    {
      Console.WriteLine(numStr + " = " +value.ToString("R", CultureInfo.InvariantCulture));
    }
    else
    {
      Console.WriteLine("Failed");
    }
  }
}