does not go inside the Windows GetMessage loop on console application

Question

I want to detect keypress in C++ and i need to use Windows System Call. So, i did some research and this is what i got using Hooks and Message:

#include <Windows.h>
#include <iostream>
#include <sstream>
#include <fstream>
#include <ctime>

using namespace std;

LRESULT CALLBACK LowLevelKeyboardProc(int code, WPARAM wParam, LPARAM lParam) {
    if (code == HC_ACTION) {
        switch (wParam) {
        case WM_KEYDOWN:
            PKBDLLHOOKSTRUCT p = (PKBDLLHOOKSTRUCT)lParam;
            char c = char(MapVirtualKey(p->vkCode, MAPVK_VK_TO_CHAR));
            cout << c << endl;
        }
    }
    return CallNextHookEx(NULL, code, wParam, lParam);
}

int main() {    
    HHOOK HKeyboard = SetWindowsHookEx(WH_KEYBOARD_LL, LowLevelKeyboardProc, 0, 0);

    MSG msg;
    BOOL bRet;

    while ((bRet = GetMessage(&msg, NULL, 0, 0)) > 0) {
        cout << "bRet = " << bRet << endl; // I want to do something here, but the program doesn't seem to go in here
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    UnhookWindowsHookEx(HKeyboard);
    return 0;
}

My question is why my program doesn't go inside the loop(and instead stuck on GetMessage function)? I need it to set conditions to terminate after some seconds, so where should i put the conditions? I know the GetMessage function reads Message, but when i press keys on my keyboard it still not going in and the callback function works just fine.

Answer 1

The events are posted to the active window. Console windows are owned by the console subsystem, csrss.exe, and it receives the events, then translates them to characters and puts them in the console object which is your application's stdin.

If you want to process events the Win32 GUI way, you should use a Win32 window (e.g. RegisterClass and CreateWindow), not a console window.

If you just want the callbacks to work for a certain period of time, you can use an alertable wait such as SleepEx or MsgWaitForMultipleObjects, which accept a timeout.