C#写入/读出文本文件
public void Page_Load(Object src,EventArgs e)
{
   StreamWriter rw = File.CreateText(Server.MapPath(".")+"//myText.txt");
   rw.WriteLine("追逐理想");
   rw.WriteLine("kzlll");
   rw.WriteLine(".NET笔记");
   rw.Flush();
   rw.Close();
}
打开文本文件
StreamReader sr = File.OpenText(Server.MapPath(".")+"//myText.txt");
StringBuilder output = new StringBuilder();
string rl;
while((rl=sr.ReadLine())!=null)
{
output.Append(rl+"<br>");
}
lblFile.Text = output.ToString();
sr.Close();

C#追加文件
    StreamWriter sw = File.AppendText(Server.MapPath(".")+"//myText.txt");
    sw.WriteLine("追逐理想");
    sw.WriteLine("kzlll");
    sw.WriteLine(".NET笔记");
    sw.Flush();
    sw.Close();