c# Convert.ToDouble format exception error

Question

I'm trying to convert this string to double

Convert.ToDouble("1.12");

and this is the output

System.FormatException was unhandled.

Should I do something like this?

    public static double ConvertToDouble(string ParseVersion)
    {
        double NewestVersion;
        try
        {
            NewestVersion = Convert.ToDouble(ParseVersion);
        }
        catch
        {
            ParseVersion = ParseVersion.Replace('.', ',');
            NewestVersion = Convert.ToDouble(ParseVersion);
        }

        return NewestVersion;
    }

    ConvertToDouble("1.12");

Or is there an easier solution?

Answer 1

You don't have to replace . to ,.. however a better way is to use the .net TryParse method like:

double d;
if (double.TryParse("your string data", out d)
{
    Console.WriteLine(d);
}

Edit: Also note that by replacing . by , you are getting a wrong results, for instance 1.12:

double d = double.Parse(1.12);//d will equals to 1.12
double d = double.Parse(1,12);//d will equals to 112.0

Answer 2

double.Parse will use the current culture by default. It sounds like you want the invariant culture:

double d = double.Parse("1.12", CultureInfo.InvariantCulture);

EDIT: Just to be clear, obviously you shouldn't use this if you're trying to parse text entered by a user in a different culture. This is for use when you've received data in the invariant culture (as most machine-to-machine data text-based formats are) and want to enforce that when parsing.

Answer 3

Convert.ToDouble uses Double.Parse internally. If you are unsure of the culture context, you should use an overload of Double.Parse precising the culture:

double d = double.Parse("1.12", CultureInfo.InvariantCulture);

Answer 4

Keep in mind, this problem can depend on where the input string comes from. If it is read from a database as an object, you might solve your problem by keeping it as an object and using Convert.ToDouble() as follows:

public double Double_fromObject(object obj)
    {
      double dNum = 0.0;
      if (obj.ToString() != string.Empty) // the Convert fails when ""
      {
        try
        {
          dNum = Convert.ToDouble(obj);
        }
        catch (SystemException sex)
        {
          // this class's error string
          LastError = sex.Message;
        }
      }

      return (dNum);
    }