001-檔案處理將字串寫入檔案

FileStream fs;
            StreamWriter sw;
            //1.檔案路徑。必須先建立檔案。        2.開啟檔案        3.執行檔案的寫入
            fs = new FileStream("C:\\test.txt", FileMode.Open, FileAccess.Write);
            sw = new StreamWriter(fs);
            sw.WriteLine("txttest");
            sw.Flush();
            sw.Close();