Question

The code is compiled in VS2008 targeting .NET3.5. This is not reproducible on my system. I suspect some sort of localization setting is at play but I don’t know much about that.

All other valid numbers seem to work fine. The bug is illustrated with this code (which causes the same exception but is not the production code):

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {
            string str = "";
            do
            {
                str = Console.ReadLine();
                Console.WriteLine("\t\"{0}\"", Convert.ToDouble(str));
            }
            while (str != null);
        }
    }
}

At the command line, input of “0” crashes the app on at least one system I have encountered.

Stack trace from user’s PC:

System.FormatException: Input string was not in a correct format.
   at System.Number.StringToNumber(String str, NumberStyles options, NumberBuffer& number, NumberFormatInfo info, Boolean parseDecimal)
   at System.Number.ParseDouble(String value, NumberStyles options, NumberFormatInfo numfmt)
   at System.Double.Parse(String s, NumberStyles style, NumberFormatInfo info)
   at System.Convert.ToDouble(String value)

Answer 1

I remember this problem from a question a while back. The Parse() methods are affected by the user overrides in the Control Panel + Region and Language applet. IIRC, it is especially sensitive to the “Negative sign symbol” setting. Ask your user to correct the settings there.

The reference question is here.