StreamWriter sw = new StreamWriter(url, “false 覆盖，true 追加”, Encoding.UTF8);

sw.Write(“内容”);

sw.Close();

FileInfo info = new FileInfo("路径");

            FileStream fs = new FileStream(pash, FileMode.OpenOrCreate, FileAccess.Read);

            byte[] b = new byte[info.Length];

            fs.Read(b, ,b.Length);

            UTF8Encoding utf = new UTF8Encoding();

            string st = utf.GetString(b);

            fs.Close();

            //st 文本内容

if (!File.Exists(file))

            {

                FileStream fs1 = new FileStream(file, FileMode.Create, FileAccess.Write);//创建写入文件

                fs1.Close();

            }     

string text = System.IO.File.ReadAllText(file);

            Console.WriteLine(text);

            //从头到尾以流的方式读出文本文件

            //该方法会一行一行读出文本

            using (System.IO.StreamReader sr = new System.IO.StreamReader(file))

            {

                string str;

                while ((str = sr.ReadLine()) != null)

                {

                    Console.WriteLine(str);

                }

            }

            Console.Read();          

System.IO.File.WriteAllText(file, string.Empty);