I've been trying some things with hooks, and I don't understand why hooks must be used with a message queue

hook = SetWindowsHookEx(WH_KEYBOARD_LL, KeyboardProc, NULL, 0);
MSG msg;
while(GetMessage(&msg, NULL, 0, 0) > 0)
{
        TranslateMessage(&msg);
        DispatchMessage(&msg);
}
UnhookWindowsHookEx(hook);

Why doesn't something like this work ?

hook = SetWindowsHookEx(WH_KEYBOARD, KeyboardProc, NULL, 0);
cin >> aKey;
UnhookWindowsHookEx(hook);

Using boost threads, and a barrier doesn't work either. Why can't the waiting between the hook and unhook be done in another manner ?

EDIT:

I did a mistake when I created this sample, I create a WH_KEYBOARD_LL hook, not WH_KEYBOARD, (I don't think it makes a big difference)

Also the loop never executes only waits on the GetMessage function.

The loop executes only when I post the quit message PostThreadMessage(id, WM_QUIT, 2323, NULL); so I don't understand what does it do beside waiting, is there some internal processing ?

RELATED:

C++ SetWindowsHookEx WH_KEYBOARD_LL Correct Setup

How can I set up a CBT hook on a Win32 console window?

c++ hook message-queue
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