private void button1_Click(object sender, EventArgs e)
        {
            OpenFileDialog of = new OpenFileDialog();
            of.ShowDialog();
            textBox1.Text = of.FileName;

            file = new FileStream(textBox1.Text, FileMode.OpenOrCreate, FileAccess.Read);

            StreamReader sr = new StreamReader(file);

            string s = sr.ReadToEnd();

            sr.Close();

            file.Close();
                       
        }

        private void button2_Click(object sender, EventArgs e)
        {
            SaveFileDialog of = new SaveFileDialog();
            of.ShowDialog();
            textBox2.Text = of.FileName;

            MessageBox.Show(textBox2.Text);

            FileStream file = new FileStream(textBox2.Text, FileMode.OpenOrCreate, FileAccess.Write);

            StreamWriter sw = new StreamWriter(file);

            sw.Write("Hello file system world!");

            sw.Close();

            file.Close();
      
        }

public static void doWrite()
      {
         FileStream file = new FileStream(@"c:\science\doWrite.txt", FileMode.OpenOrCreate, FileAccess.Write);
         StreamWriter sw = new StreamWriter(file);
         sw.Write("Hello file system world!");
         sw.Close();
         file.Close();
      }

public static void doWrite2()
      {
         StreamWriter sw = new StreamWriter(@"c:\science\doWrite.txt");
         sw.Write("Hello file system world!");
         sw.Close();
      }