Generate a beep in the PC speaker using C# and an unmanaged call to the Beep() function that is part of the Windows kernel.

1. using System;
2. using System.Collections.Generic;
3. using System.ComponentModel;
4. using System.Data;
5. using System.Windows.Forms;
6. using System.Runtime.InteropServices;
7. 
8. namespace Sample
9. {
10.    public partial class Form1 : Form
11.    {
12.        public Form1()
13.       {
14.            InitializeComponent();
15.        }
16. 
17.        [DllImport("kernel32.dll")]
18.        public static extern bool Beep(int BeepFreq, int BeepDuration);
19. 
20.        private void button1_Click(object sender, EventArgs e)
21.        {
22.            Beep(500, 100);
23.        }
24.    }
25.}