Locking Your Computer with C#

In order to lock your computer, you need to use the following two APIs:

[DllImport("user32.dll")]
        public static extern void LockWorkStation();      
        [DllImport("user32.dll")]
        public static extern int ExitWindowsEx(int uFlags, int dwReason); 

You should implement it as follows:

// Lock computer
      void btnLock_Click(object sender, System.EventArgs e)
      {
         LockWorkStation();
      }
// Log Off
      void btnLogOff_Click(object sender, System.EventArgs e)
      {
         if(DialogResult.Yes==MessageBox.Show("Log Off?","Log Off", MessageBoxButtons.YesNo, MessageBoxIcon.Question, MessageBoxDefaultButton.Button2))
         ExitWindowsEx(0, 0);
      }
   // Shutdown
      void btnShutdown_Click(object sender, System.EventArgs e)
      {
         if(DialogResult.Yes==MessageBox.Show("Shutdown?","Shutdown", MessageBoxButtons.YesNo, MessageBoxIcon.Question, MessageBoxDefaultButton.Button2))
         ExitWindowsEx(1, 0 );