不能double.Parse字符串

Question

I have a problem with parsing a string to a double. I have a StreamWriter reading lines from a text file. The text file has the following lines:

17-09-2012: (100,98)
17-09-2012: (50,57)

Now, I want to use the values from inside the parantheses, add them together and display them in a textbox. So far I have the following:

int counter = 0;
double res = 0;
string line;

System.IO.StreamReader file = new System.IO.StreamReader("d:\\test.txt");
while ((line = file.ReadLine()) != null)
{
    string par = Regex.Match(line, @"\(([^)]*)\)").Value;
    double par2 = double.Parse(par);
    res += par2;

    counter++;
}
file.Close();
textBox1.Text = res.ToString();

However, apparently the input string is not in a correct format, which I find rather odd, since the regex should remove everything but the numbers inside the parantheses. I have even checked for this by writing the string to the textbox without first adding them together, and it showed "100,9850,57" . So truly, I do not understand, why it cannot convert the string to a double.

I hope you can tell me, what I am doing wrong.

Answer 1

你的“par”变量包含一个看起来像这样的字符串：“（100,98）”这就是它无法解析的原因。

Answer 2

将你的正则表达式改为(?<=\\()(([^)]*))(?=\\))

Answer 3

You can try with - based on InvariantCulture

 var culture = CultureInfo.InvariantCulture;
 double result = double.Parse(par , culture);

Answer 4

You can force double.Parse to use a culture that uses , as a decimal separator, like this:

CultureInfo culture = new CultureInfo("de-DE");
double d = double.Parse(par, culture);

That's a good idea anyway, if you want your program to work also on computers with different regional settings.

Answer 5

Setting your regex to (?<=\\()(([^)]*))(?=\\)) and using this helper should solve your problems:

        public static double ParseDouble(string input)
        {
            // unify string (no spaces, only . )
            string output = input.Trim().Replace(" ", "").Replace(",", ".");

            // split it on points
            string[] split = output.Split('.');

            if (split.Count() > 1)
            {
                // take all parts except last
                output = String.Join("", split.Take(split.Count() - 1).ToArray());

                // combine token parts with last part
                output = String.Format("{0}.{1}", output, split.Last());
            }

            // parse double invariant
            double d = Double.Parse(output, CultureInfo.InvariantCulture);
            return d;
        }

Answer 6

I made it work, by making a try, catch:

string par = Regex.Match(line, @"(?<=\()(([^)]*))(?=\))").Value;
                try
                {
                    double par2 = double.Parse(par);
                    res += par2;
                }
                catch
                {
                }

Thanks, everyone for your help.