C#创建txt文件并写入内容

        //注册
        public string registered(string username,string password)
        {
            //判断是否已经有了这个文件
            if (!System.IO.File.Exists("c:\\users\\administrator\\desktop\\webapplication1\\webapplication1\\testtxt.txt"))
            {
               //没有则创建这个文件
                FileStream fs1 = new FileStream("c:\\users\\administrator\\desktop\\webapplication1\\webapplication1\\testtxt.txt", FileMode.Create, FileAccess.Write);//创建写入文件 
               //设置文件属性为隐藏
                System.IO.File.SetAttributes(@"c:\\users\\administrator\\desktop\\webapplication1\\webapplication1\\testtxt.txt",  FileAttributes.Hidden);    
                StreamWriter sw = new StreamWriter(fs1);
                sw.WriteLine(username.Trim() + "+" + password.Trim());//开始写入值
                sw.Close();
                fs1.Close();
                return "注册成功";
            }
            else
            {
                FileStream fs = new FileStream("c:\\users\\administrator\\desktop\\webapplication1\\webapplication1\\testtxt.txt", FileMode.Open, FileAccess.Write);
                System.IO.File.SetAttributes(@"c:\\users\\administrator\\desktop\\webapplication1\\webapplication1\\testtxt.txt", FileAttributes.Hidden);
                StreamWriter sr = new StreamWriter(fs);
                sr.WriteLine(username.Trim() + "+" + password.Trim());//开始写入值
                sr.Close();
                fs.Close();
                return "注册成功";
            }

        }

        //登录
        public string Logins(string username, string password)
        {
            string flag = null;
             //循环读取文件的内容
            string[] lines = System.IO.File.ReadAllLines("c:\\users\\administrator\\desktop\\webapplication1\\webapplication1\\testtxt.txt", Encoding.Default);
            if (username != null&& password!=null)
            {
                string[] str;//定义一个数组
                if (lines != null)
                {
                    for (int i = 0; i