HOW DO YOU EDIT A TEXT FILE?

The easiest way is to read the whole file, make the changes to the text and then write it all back, overwriting the original file. Here's an example.

Suppose you have this textfile, salfile.txt, and you want to interchange the second and fourth lines:

First
Fourth
Third
Second

This console program (.NET 2.0) should achieve this:

using System;
using System.IO;
using System.Collections.Generic;

class Test
{

     static void Main()
     {

        string line = null;
        List lines = new List();      
        StreamReader reader = new StreamReader("salfile.txt");
     
        // read all the lines in the file and store them in the List
        while((line = reader.ReadLine()) != null)
        {
            lines.Add(line);
        }
      
        reader.Close();

        // change the second line
        lines[1] = "Second";
        // change the fourth line
        lines[3] = "Fourth";

        StreamWriter writer = new StreamWriter("salfile.txt");
       
        // write the lines back to the file, overwriting the original one
        for (int i = 0; i < lines.Count; i++)
        {
            if (i < lines.Count - 1)
               Console.WriteLine(lines[i]);
            else
               Console.Write(lines[i]);
        } 
        writer.Close();

        // check it worked
        reader = new StreamReader("salfile.txt");
        while((line = reader.ReadLine()) != null)
        {
            Console.WriteLine(line);
        }

        reader.Close();
      
        Console.WriteLine("\n\nPress any key to end the program");
        Console.ReadKey();
      }
}