Converting string to double in C#

Question

I have a long string with double-type values separated by # -value1#value2#value3# etc

I splitted it to string table. Then, I want to convert every single element from this table to double type and I get an error. What is wrong with type-conversion here?

string a = "52.8725945#18.69872650000002#50.9028073#14.971600200000012#51.260062#15.5859949000000662452.23862099999999#19.372202799999250800000045#51.7808372#19.474096499999973#";
string[] someArray = a.Split(new char[] { '#' });
for (int i = 0; i < someArray.Length; i++)
{
    Console.WriteLine(someArray[i]); // correct value
    Convert.ToDouble(someArray[i]); // error
}

Solution 1

There are 3 problems.

1) Incorrect decimal separator

Different cultures use different decimal separators (namely , and .).

If you replace . with , it should work as expected:

Console.WriteLine(Convert.ToDouble("52,8725945"));

You can parse your doubles using overloaded method which takes culture as a second parameter. In this case you can use InvariantCulture (What is the invariant culture) e.g. using double.Parse:

double.Parse("52.8725945", System.Globalization.CultureInfo.InvariantCulture);

You should also take a look at double.TryParse, you can use it with many options and it is especially useful to check wheter or not your string is a valid double.

2) You have an incorrect double

One of your values is incorrect, because it contains two dots:

15.5859949000000662452.23862099999999

3) Your array has an empty value at the end, which is an incorrect double

You can use overloaded Split which removes empty values:

string[] someArray = a.Split(new char[] { '#' }, StringSplitOptions.RemoveEmptyEntries);

Solution 2

Add a class as Public and use it very easily like convertToInt32()

  using System;
  using System.Collections.Generic;
  using System.Linq;
  using System.Web;

  /// <summary>
  /// Summary description for Common
  /// </summary>
  public static class Common
  {
     public static double ConvertToDouble(string Value) {
        if (Value == null) {
           return 0;
        }
        else {
           double OutVal;
           double.TryParse(Value, out OutVal);

           if (double.IsNaN(OutVal) || double.IsInfinity(OutVal)) {
              return 0;
           }
           return OutVal;
        }
     }
  }

Then Call The Function

double DirectExpense =  Common.ConvertToDouble(dr["DrAmount"].ToString());

Solution 3

Most people already tried to answer your questions.
If you are still debugging, have you thought about using:

Double.TryParse(String, Double);

This will help you in determining what is wrong in each of the string first before you do the actual parsing.
If you have a culture-related problem, you might consider using:

Double.TryParse(String, NumberStyles, IFormatProvider, Double);

This http://msdn.microsoft.com/en-us/library/system.double.tryparse.aspx has a really good example on how to use them.

If you need a long, Int64.TryParse is also available: http://msdn.microsoft.com/en-us/library/system.int64.tryparse.aspx

Hope that helps.

Solution 4

private double ConvertToDouble(string s)
    {
        char systemSeparator = Thread.CurrentThread.CurrentCulture.NumberFormat.CurrencyDecimalSeparator[0];
        double result = 0;
        try
        {
            if (s != null)
                if (!s.Contains(","))
                    result = double.Parse(s, CultureInfo.InvariantCulture);
                else
                    result = Convert.ToDouble(s.Replace(".", systemSeparator.ToString()).Replace(",", systemSeparator.ToString()));
        }
        catch (Exception e)
        {
            try
            {
                result = Convert.ToDouble(s);
            }
            catch
            {
                try
                {
                    result = Convert.ToDouble(s.Replace(",", ";").Replace(".", ",").Replace(";", "."));
                }
                catch {
                    throw new Exception("Wrong string-to-double format");
                }
            }
        }
        return result;
    }

and successfully passed tests are:

        Debug.Assert(ConvertToDouble("1.000.007") == 1000007.00);
        Debug.Assert(ConvertToDouble("1.000.007,00") == 1000007.00);
        Debug.Assert(ConvertToDouble("1.000,07") == 1000.07);
        Debug.Assert(ConvertToDouble("1,000,007") == 1000007.00);
        Debug.Assert(ConvertToDouble("1,000,000.07") == 1000000.07);
        Debug.Assert(ConvertToDouble("1,007") == 1.007);
        Debug.Assert(ConvertToDouble("1.07") == 1.07);
        Debug.Assert(ConvertToDouble("1.007") == 1007.00);
        Debug.Assert(ConvertToDouble("1.000.007E-08") == 0.07);
        Debug.Assert(ConvertToDouble("1,000,007E-08") == 0.07);

Solution 5

You can try this example out. A simple C# progaram to convert string to double

class Calculations{

protected double length;
protected double height;
protected double width;

public void get_data(){

this.length = Convert.ToDouble(Console.ReadLine());
this.width  = Convert.ToDouble(Console.ReadLine());
this.height = Convert.ToDouble(Console.ReadLine());

   }
}

View more solutions

Comments

[Dave Bish]

What error? It works fine for me...

[Stefan H]

@DaveBish try looping through all of them, you'll see that index 5 is a bad string to convert to a double.

[Admin]

@StefanH: Of course, but index 0 appears to be good.

[Matt]

One of your input values has two decimal places.

[NominSim]

Look at the bytes of the string tablicaLatLng[0], that should show you what is wrong.

[Jodrell]

If the strings don't meet the formats and bounds described on MSDN then they won't be convertible, I suggest reading MSDN. msdn.microsoft.com/en-us/library/zh1hkw6k.aspx. What exceptions do you get, that will be the clue.

[Admin]

I have compiled your code and I do not have any problems building it. What error are you getting? Is this all the code?

[Admin]

I am voting to close as too localized. This seems like an issue no one can provide a suitable answer for at the moment and it is simply frustrating folks.

[Zbigniew]

@0A0D check my answer, it should fix this problem

[Stefan H]

@Ramhound If it is any consolation it looks as though you were wrong (we both were). The issue was in fact someone trying to parse values from one culture into another. The OP's question had some red herrings in it, but we both made assumptions about what the issue was (due to some bad info on the OP's part) that lead us down the wrong path.

[Adrian Ratnapala]

Perhaps this should not be closed. It is not "only relevant to a small geographic area". It is always a bug to use a locale-dependent function for a locale-independent problem; it's a very common bug. And it's as much a bug in Kansas as in Munich. Only in Kansas it's harder to find. (BTW: I found this question because I had exactly this bug in my code, do I count as a future visitor?)

[Zbigniew]

Thanks for the downvotes and explanations. I have accually tried to convert version with . and it gave me StringFormatException, when I changed it to , it worked (culture: pl_PL). This is also answer for his question (regarding first double).

[whoah]

yea, replacing . with , works fine but I have to get a values with ., not with , (for google api - lat and lng requires '.').

[Rob I]

+1 good catch. Can you tell @whoah how to "change culture" for parsing? Or parse in a different culture?

[Zbigniew]

@Robl sure thing, it has happend to me once so it was first thing in my mind :P

[whoah]

great ! this works perfect :) could you tell me, what means this part? System.Globalization.CultureInfo.InvariantCulture? Big thanks for help, greetings!

[Zbigniew]

@whoah Read this: InvariantCulture and this: What is the Invariant Culture?

[whoah]

@des - wow, great, now understand :) thanks for help! and one simply question - why my first post get "-1"? What is wrong? I think that problem presented in question wasn't so stupid :p

[Stefan H]

@whoah I don't think the question was stupid, but rather due to the other issues in your question, there were a few red herrings which made it difficult to determine what your actual problem was.

[Bengi Besçeli]

But there is not a method named TryParse.

[Syaiful Nizam Yahya]

@Zbigniew Downvotes you say? Here an upvote. Thanks. Solved my problem.

[Zbigniew]

@SyaifulNizamYahya old times, right now this answer has +90/-1 :P Thanks for the upvote though. Because of all the upvotes I decided to edit and expand my answer.