Converting Strings from an Array into Double values in C#

Question

So any entry on my Database has (ID, tag, value, timestamp, status).

I´ll load one entry into 'profilData' and then only concentrate on the "value" row.

DataTable profilData = skzAdapterText.LoadValuesText(time);
String SQLvalues = (String)profilData.Rows[0][2];

The String I get looks similar to this:

NaN#Nan#44.20216139610997#45.35340149990988#45.44329482112824#45.1593428796393#NaN#NaN

I then split that String at each '#' and store the results in an Array.

String[] values;
values = SQLvalues.Split('#');

My aim is to be able to sum those values up. I am currently trying to Parse or Convert the String into a Double but whenever I do so the Double looks like this:

4420216139610997

The point/comma just gets removed.

Since I am in my first year of Education I don´t have much experience on all of this. Any help is appreciated.

Full Code:

String[] values;
List<Double> valueList = new List<Double>();

int profilePosCount = 5;

for (int i = 0; i < profilePosCount; i++)
{
    int n = 0;
    DataTable profilData = skzAdapterText.LoadValuesText(time);
    String SQLvalues = (String)profilData.Rows[0][2];
    n++;

    values = SQLvalues.Split('#');

    double summe = 0;
    int counter = 0;


    foreach (String tmpRow in values)
    {
        try
        {
            Double value = Convert.ToDouble(tmpRow);   //Double.Parse(tmpRow);

            counter++;

            if (!tmpRow.ToString().Equals("NaN"))
            {
                if (!value.ToString().Equals("0"))
                {
                    summe = summe + value;
                }
            }
        }
        catch (Exception ex)
        {
        }
     }

        if (summe != 0 && counter != 0)
            valueList.Add(summe / counter);
   }

A DataTable is quite capable of storing typed data - double elements stored as double. So you can skip the step of casting to string and get doubles directly. An empty catch is another bad idea. — Ňɏssa Pøngjǣrdenlarp
– Ňɏssa Pøngjǣrdenlarp, Commented Aug 9, 2022 at 13:18
Probably your regional settings for the decimal separator is a comma, not a dot. Try Double.Parse(tmpRow, CultureInfo.InvariantCulture) — Klaus Gütter
– Klaus Gütter, Commented Aug 9, 2022 at 13:23

Markus · Accepted Answer · 2022-08-10 06:57:02Z

1

When using double.Parse or Convert.ToDouble without any culture info, the current culture of the thread is used (usually this is based on the regional settings of your computer). You can also specify the regional settings to use when parsing the double, so that your code can use exactly the settings that were used when the double was converted to a string. This way, your code does not depend on regional settings from your computer anymore.

The doubles in the string use the dot as the decimal separator. If you do not know the exact culture, you can use the InvariantCulture when parsing the doubles.

The following sample uses TryParse instead of Parse in order to cope with strings that cannot be parsed:

foreach (String tmpRow in values)
{
  Double value;
  if (double.TryParse(
        tmpRow, 
        NumberStyles.Float | NumberStyles.AllowThousands, 
        CultureInfo.InvariantCulture, 
        out value)
      && !double.IsNaN(value))
  {
    counter++;
    summe = summe + value;
  }
}

In order for the sum to work I added a check against NaN to the condition.

edited Aug 10, 2022 at 6:57

answered Aug 9, 2022 at 13:41

Markus

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4 Comments

Klaus Gütter Over a year ago

double.Parse("NaN") works just fine.

Astirak Over a year ago

Thanks for the explaination, now that I implemented this Code it is working just the way I wanted it to work. Appreciate it!

Astirak Over a year ago

@Markus could I also just have replaced the dot with a comma and it would have been parsed correctly?

Markus Over a year ago

I assume you are running on german regional settings. This would have solved the parsing problem - as long as there would not have been thousand separators in the numbers (often commas in other regional settings / InvariantCulture). So specifying the culture is definitely the safer approach.

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