using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Text; using System.Windows.Forms; using System.Runtime.InteropServices; namespace VolumnSet {   public partial class Form1 : Form   {     [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]     static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, uint wParam, uint lParam);     const uint WM_APPCOMMAND = 0x319;     const uint APPCOMMAND_VOLUME_UP = 0x0a;     const uint APPCOMMAND_VOLUME_DOWN = 0x09;     const uint APPCOMMAND_VOLUME_MUTE = 0x08;     public Form1()     {       InitializeComponent();     }     private void button1_Click(object sender, EventArgs e)     {       //加音量       SendMessage(this.Handle, WM_APPCOMMAND, 0x30292, APPCOMMAND_VOLUME_UP * 0x10000);     }     private void button2_Click(object sender, EventArgs e)     {       //減音量       SendMessage(this.Handle, WM_APPCOMMAND, 0x30292, APPCOMMAND_VOLUME_DOWN * 0x10000);     }     private void checkBox1_CheckedChanged(object sender, EventArgs e)     {       //靜音       SendMessage(this.Handle, WM_APPCOMMAND, 0x200eb0, APPCOMMAND_VOLUME_MUTE * 0x10000);     }   } }