using System;
using System.IO;
using System.Text;
class Test
{
public static void Main()
{
string path = @"c:\MyTest.txt";
if (!File.Exists(path))
{
string createText = "Hello " + Environment.NewLine;
File.WriteAllText(path, createText, Encoding.UTF8);
}
string appendText = "extra text" + Environment.NewLine;
File.AppendAllText(path, appendText, Encoding.UTF8);
string readText = File.ReadAllText(path);
Console.WriteLine(readText);
}
}