Keep getting "Input string not in correct format" when trying to read data from a text file using StreamReader

Question

I've had the error when I was still using double.parse or int.parse in place of ConvertToDouble and ConvertToInt32, respectively. Here's the code:

         ArrayList Webpages = new ArrayList();
         String FileName = "Medium.txt";
         StreamReader newSR = new StreamReader(FileName);
         while (!newSR.EndOfStream)
         {
             string[] data = (newSR.ReadLine()).Split(',');
             Webpage newEntry = new Webpage();
             newEntry.size = Convert.ToDouble(data[0]);
             newEntry.visitCount = Convert.ToInt32(data[1]);
             newEntry.name = data[2];
             Webpages.Add(newEntry);
         }

And the Textfile:

5.26,46,WebPage1
7.44,76,WebPage2
8.35,42,WebPage3
46.2,9,WebPage4
12.44,124,WebPage5
10.88,99,WebPage6
10.66,984,WebPage7

This is my error message:

An unhandled exception of type 'System.FormatException' occurred in mscorlib.dll

Additional information: Input string was not in a correct format. I'm getting the error message by the line that reads: newEntry.size = Convert.ToDouble(data[0])

Have you debugged to check what the value of data[0] is when it fails? (I'm wondering whether you're reading a blank line at the end of the file.) Is it possible that you're in a culture where the decimal separate is , rather than .? — Jon Skeet
– Jon Skeet, Commented Apr 7, 2018 at 9:52
tried your code, its working except I didnt used your Webpage newentry object, what is it ?? — user9610723
– user9610723, Commented Apr 7, 2018 at 10:03

Adem Catamak · Accepted Answer · 2018-04-07 11:58:52Z

3

Computer culture effect your delimeter types. In this case if delimeter is . you can add InvariantCulture options.

    newEntry.size = Convert.ToDouble(data[0], CultureInfo.InvariantCulture);

Also end of file may leads error if there is empty line. This way can be more secure.

 while (!newSR.EndOfStream)
 {
     string line = newSR.ReadLine();
     if(string.IsNullOrEmpty(line)
         break;
     string[] data = (line).Split(',');
     ............

edited Apr 7, 2018 at 11:58

answered Apr 7, 2018 at 9:59

Adem Catamak

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1 Comment

Mong Zhu Over a year ago

neither double.Parse nor Convert.ToDouble throw a System.FormatException if the delimiter is , or .. They simply parse the value wrong. So culture dependent delimiter cannot be the problem here

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