如何正确摘机？

Question

I made a very simple Hook codes (I'm a beginner).

I opened Notepad and tested.

If I press ANY key it make a beep and printed itself.

Except "x" key, it is a terminator key.

Question :

I do not want to see "x" key printed. I just quit the program. What do I have to do ?

namespace HookingStudy
{
    class HookingClass          
    {
        private const int WM_KEYDOWN = 0x0100;
        private static LowLevelKeyboardProc _proc = hookCallBack;
        private static IntPtr _hookID = IntPtr.Zero;                    
        public static void Main()
        {
            Beep(1111, 222);
            _hookID = SetHook(_proc);
            Application.Run();
        }
        private static IntPtr hookCallBack(int nCode, IntPtr wParam, IntPtr lParam)
        {
            if( nCode >= 0 && wParam == (IntPtr) WM_KEYDOWN )
            {
                int vkCode = Marshal.ReadInt32(lParam);
                if( vkCode.ToString() == "88" )                 //   88 ("x" key)
                {
                    Beep(7777, 222);
                    UnhookWindowsHookEx(_hookID);     
                    Process.GetCurrentProcess().Kill(); 
                }
                Beep(2222, 55);
            }
            return CallNextHookEx(_hookID, nCode, wParam, lParam);  
        }
        private static IntPtr SetHook(LowLevelKeyboardProc proc)
        {
            using( Process curProcess = Process.GetCurrentProcess() )
            using( ProcessModule curModule = curProcess.MainModule )
            {
                return SetWindowsHookEx(13, proc, GetModuleHandle(curModule.ModuleName), 0);
            }                   
        }
        private delegate IntPtr LowLevelKeyboardProc(int nCode, IntPtr wParam, IntPtr lParam);
        [DllImport("KERNEL32.DLL")]                             
        extern public static void Beep(int freq, int dur);      
        [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        private static extern IntPtr SetWindowsHookEx(int idHook, LowLevelKeyboardProc lpfn, IntPtr hMod, uint dwThreadId);
        [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        [return: MarshalAs(UnmanagedType.Bool)]
        private static extern bool UnhookWindowsHookEx(IntPtr hhk);
        [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        private static extern IntPtr CallNextHookEx(IntPtr hhk, int nCode, IntPtr wParam, IntPtr lParam);
        [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        private static extern IntPtr GetModuleHandle(string lpModuleName);
    }  
}

Answer 1

I do not want to see the terminator x printed at Notepad

Then do not call next hook in chain:

return CallNextHookEx(_hookID, nCode, wParam, lParam);

The idea of hooking it to install own handler prior existing handlers (afair from winapi). By intercepting (like you are doing it already) you are not only listening , but still invoking previous handlers with that call.

Try something like (untested):

if( vkCode == 88)
{
    ...
    return 0;
}