-3

I've been working all day trying to convert a string from a text file into a double array but can't figure out why I am getting the error "the file could not be read; input string was not in the correct format".

I currently have a application that reads back the contents of the text file in a string. I want it that when the string is converted into the double array I can then tell the console to print the double array and it will print the values of the text file that was in the string originally.

Here is my code:

double[] x = new double [3501];

This is where I define the double array. I do this first:

try
{
  using (StreamReader sr = new StreamReader("test.txt"))
  {
     String line =  sr.ReadToEnd();
     string[] fields = line.Split(new char[] { ' ' });
     x = new double [fields.Length];

     for (int i = 0; i < fields.Length; i++)
     {
        x[i] = Convert.ToDouble(fields[i]);
        Console.WriteLine(x[i]);
     }

Line is the input string that contains a column full of numbers and is then split. I then tell it to print the contents of x[i] but thats when an exception is thrown:

catch (Exception e)
{
   // Log the exception and quit...                
   Console.WriteLine("The file could not be read:");
   Console.WriteLine(e.Message);
}

Can anyone figure what is wrong with my code and why it's not working?

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11
  • 5
    What is the exact wording of the Message that the exception is returning? Commented Apr 11, 2013 at 20:56
  • 2
    I have the weirdest deja-vu right now Commented Apr 11, 2013 at 20:57
  • Check the value of the string you're trying to convert that's throwing the exception. Commented Apr 11, 2013 at 20:57
  • Instead of e.Message you should capture e.ToString() - this way you get inner exceptions and stacktrace. Commented Apr 11, 2013 at 20:58
  • 2
    Oh, hell. Never mind, it's at the top of your question: input string was not in the correct format. Pretty much says it all; one of your input values could not be parsed by the Convert.ToDouble function. Commented Apr 11, 2013 at 20:58

4 Answers 4

Reset to default
4

One of the strings you're converting can't be parsed with ToDouble

So do this instead (inside your loop):

double parsed = 0;
try 
{
    parsed = Convert.ToDouble(fields[i]);
}
catch (FormatException e) 
{ 
    Console.WriteLine("Couldn't parse '{0}'", fields[i]);
    continue;
}

x[i] = parsed;
Console.WriteLine(parsed);

This will catch the FormatException, print what it couldn't read, and go to the next iteration the loop. If it does not encounter an exception, it will print the parsed double.

You can see the exception is detailed here: http://msdn.microsoft.com/en-us/library/zh1hkw6k.aspx

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4 Comments

Thanks this does work but is there anyway it can work with a double array? I kind on need it be an array.
@TireniDada Forgot to actually set x[i] to the parsed value. See my edit -- right before the last WriteLine
@TireniDada If this is the solution to your answer, would you mind marking my answer as accepted?
Done sorry I took so long to do it.
0

According to MSDN, the parameter to the constructor of the StreamReader must be the complete path to the file, not just a relative path. From the page:

The complete file path is specified by the path parameter. This constructor initializes the encoding to UTF8Encoding and the buffer size to 1024 bytes.

When it was telling you the file could not be read, that looks like it is pointing to an IOException as being the problem.

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2 Comments

The OP is writing the message "The file could not be read" in his own code.
Bah, just re-read the code where you print the exception. I see the file not being read is something you added. Nonetheless, try changing the constructor parameter to the complete path & see if it helps.
0

You must ensure that your StreamReader path is accessible. For instance, try changing the line:

using (StreamReader sr = new StreamReader("test.txt"))

to something along the lines of...

using (StreamReader sr = new StreamReader("C:\\Zach\\Documents\\test.txt"))

That is the only change I made and I can see the console printing every value as a double.

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Comments

-1

Maybe you are reading the last line and there's no value there, so when you try to convert catch the exception. Try with fields.Length-1 in your FOR. Or like @Robert Harvey said, one of your values cold not be parsed.

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1 Comment

Hmm... You would think he'd be getting an "Index out of range" error. That probably still needs to be fixed, but the reported problem is most likely a parsing error occurring before i can get too large. The problem is most likely in the first input line from the file.

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