How to save Text file using Filter property in c# visual studio

Saving Text files in C#

Step 1- we need to add  Textbox & Button.
Step 2-Here is the code copy & paste to the button1 click event.

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

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

        private void button1_Click(object sender, EventArgs e)
        {
            SaveFileDialog sfd = new SaveFileDialog();
            sfd.Filter = "Text file (*.txt)|*.txt|C# file (*.cs)|*.cs";
            sfd.ShowDialog();
            File.WriteAllText(sfd.FileName, textBox1.Text);
           MessageBox.Show("Details saved");
         
        }
    }