讀取

using (StreamReader l_file = new StreamReader(Server.MapPath("sample_tsmc_ecoa.csv"), System.Text.Encoding.Default))
{
    string l_file_txt = l_file.ReadToEnd();
}

寫入

using (System.IO.StreamWriter l_file = new System.IO.StreamWriter(Server.MapPath("coaa.csv"), false, System.Text.Encoding.Default))
{
    l_file.Write("abcd");
}