Filestream读取或写入文件

 using System.IO;//引用 System.IO
 namespace filestream
 {
     public partial class Form1 : Form
     {
         public Form1()
         {
             InitializeComponent();
         }

         private void btnWrite_Click(object sender, EventArgs e)
         {
             SaveFileDialog sfd = new SaveFileDialog();

             sfd.Filter = "文本文件|*.txt|c#文件|*.cs";

             if (sfd.ShowDialog() == System.Windows.Forms.DialogResult.OK)
             {
                 txtPath.Text = sfd.FileName;//保存的路径
                 using (FileStream fs = new FileStream(txtPath.Text, FileMode.Create))
                 {
                     string txt = txtContent.Text;
                     byte[] buffer = Encoding.UTF8.GetBytes(txt);
                     fs.Write(buffer, , buffer.Length);
                 }
             }
         }

         private void btnRead_Click(object sender, EventArgs e)
         {
             OpenFileDialog ofd = new OpenFileDialog();
             ofd.Filter = "文本文件|*.txt";
             if (ofd.ShowDialog() == System.Windows.Forms.DialogResult.OK)
             {
                 txtPath.Text  = ofd.FileName;
                 using (FileStream fs = new FileStream(txtPath.Text, FileMode.Open))
                 {
                     //byte[] buffer = new byte[fs.Length];
                     //fs.Read(buffer, 0, buffer.Length);

                     //string msg = Encoding.UTF8.GetString(buffer);
                     //txtContent.Text = msg;

                     using (StreamReader sr = new StreamReader(fs,Encoding.UTF8))
                     {
                         string msg = sr.ReadToEnd();
                         txtContent.Text = msg;
                     }
                 }
             }
         }
     }
 }