c# write text to existing file code example
Example 1: c# append to file
File.AppendAllText(@"c:\path\file.txt", "text content" + Environment.NewLine);
Example 2: streamwriter append text
using (FileStream fs = new FileStream(fileName,FileMode.Append, FileAccess.Write))
using (StreamWriter sw = new StreamWriter(fs))
{
sw.WriteLine(something);
}