How to save Textbox data in a file

using System;
using System.IO;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        //
        // This is the button labeled "Save" in the program.
        //
        File.WriteAllText("C:\\demo.html", textBox1.Text);
    }
    }
}

//Use StreamWriter class.
StreamWriter sw = new StreamWriter("E:\\test.html");
 
//Use write method to write the text
sw.Write(textBox1.Text);
 
//always close your stream
sw.Close();