Thread: Trying to understand Files better

Nothing really jumps out at me unfortunately.

Well, it could be as simple as the StreamWriter needing to be flushed. There is a StreamWriter.Flush() method for that, but I think a using block would make things easier. Using blocks also really make things easier from an RAII standpoint; ensuring that files are flushed/closed, and it's a good habit to get into now, since when you get to a bit of a higher level you will be dealing with exceptions and will want a neat approach.

In general, paying attention to scope really helps.

Code:

using (StreamReader sr = File.OpenText(INPUT))
{
   for(int i = 0; i < data + 1; i++)
   {
      words[i] = sr.ReadLine();
   }
}

using (StreamWriter sw = File.CreateText(OUTPUT))
{
   foreach(string word in words)
   {
      sw.WriteLine(word);
   }
}

If code like this doesn't help then the next likely suspect is the file location. I suggest getting the environment to help you pick a good folder for your stuff.
Environment.GetFolderPath()

Define "doesn't work".

Is your words[] array populated with the right number of lines? Are any of them written to the output file? Do you get any exceptions?

I see several possible problems - mainly related to how you are coding the number of lines into the file, and you use this for output, but not for input - i.e. your input could overrun your array, or it could only partially fill it. If you actually needed to read the file into an array (rather than just immediately echo each line from input to output) you should at the very least have error checking in case I give your code a 10 line file, or a 2 line file.

Add some debug code?

Code:

using System;
using System.IO;

namespace FileExperiment
{
    class Program
    {
        const string INPUT = "\\Projects\\FileExperiment\\FileExperiment\\Test.txt";
        const string OUTPUT = "\\Projects\\FileExperiment\\FileExperiment\\outfile.txt";

        static int data = 4;
        static string[] words = new string[data + 1]; //use the +1 string to hold an error code

        static StreamReader fileIn;
        static StreamWriter fileOut;

        static void Main()
        {
            fileIn = File.OpenText(INPUT);
            fileOut = File.CreateText(OUTPUT);

	    //init the array so we know if any line is empty
	    for (int i = 0; i < data; i++)
	    {
	         words[i] = string.Format("No input into line number {0}.",i.ToString());
	    }
        
            InputData();

            for (int i = 0; i < data; i++)
                fileOut.WriteLine("{0}",words[i]);

	    //if there was an error code then display it (write to the file?)
	   if(words[data].Length() > 0)
	   {
			fileOut.WriteLine("{0}",words[data]);	
	   }

            Console.ReadLine();


        }



        static void InputData()
        {
            string word;

            int i = 0;

            while ((word = fileIn.ReadLine()) != null)
            {
		
		//check for too much input
		if(i == data)
		{
			words[data] = string.Format("Too many lines ({0}) in input file!", data.ToString() );
			return;
		}

                words[i] = word;
                i++;

            }

  	     //check we got some input
	     if(i == 0)
	    {
		words[data] = string.Format("No lines in input file!");
	    }
      }


    }
}