GetMessage() hanging up

Question

I have read the msdn link, and tried to approach the GetMessage() function in the following keylogger-code .

In my smallest version of a program attached below, why isn't GetMessage() releasing and print "new message" if I press keyboard or resize window?

#include <stdio.h>
#inlcude <stdlib.h>
#inlcude <windows.h>

int main() {
    MSG msg;
    while (GetMessage(&msg, NULL, 0, 0) != 0) {
        printf("\nnew message!");
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return 0;
}

UPDATE: As you mentioned I gave the process a window(handle) and it worked fine during I kept the GetMessage() within the WinMain. Because there should be other functionality I need to outsource the GetMessage() to its own thread as shown below. Unfortunately the GetMessage() function hangs up again, even though I specify the window-handle for which the messages should be recieved within its parameters. Any hints to get me further in understanding this function?

void control(HWND hwnd) {
    MSG msg;
    while (GetMessage(&msg, NULL, 0, 0) != 0) {
        printf("\nnew message!");
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return 0;
}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) {
    // window class creation
    const char window_name[] = "myWindow";
    WNDCLASSEX wc;
    wc.cbSize = sizeof(WNDCLASSEX);
    wc.style = 0;
    wc.lpfnWndProc = WndProc;
    wc.cbClsExtra = 0;
    wc.cbWndExtra = 0;
    wc.hInstance = hInstance;
    wc.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
    wc.lpszMenuName = NULL;
    wc.lpszClassName = window_name;
    wc.hIconSm = LoadIcon(NULL, IDI_APPLICATION);
    // register the class
    if(!RegisterClassEx(&wc)) {
        MessageBox(NULL, "Window Registration Failed!", "Error!", MB_ICONEXCLAMATION | MB_OK);
        return 0;
    }

    // window creation
    HWND hwnd;
    hwnd = CreateWindowEx(WS_EX_CLIENTEDGE, window_name, "The Window Title", WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, 240, 120, NULL, NULL, hInstance, NULL);
    if(hwnd == NULL) {
        MessageBox(NULL, "Window Creation Failed!", "Error!", MB_ICONEXCLAMATION | MB_OK);
        return 0;
    }

    // show window
    ShowWindow(hwnd, nCmdShow);
    UpdateWindow(hwnd);

    // threading
    HANDLE thread
    thread = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE*) control, hwnd, 0, NULL);

    WaitForSingleObject(thread, INFINITE);
    return 0;
    }

Answer 1

Your program has not windows attached to it. As you use printf and main, I assume that it is a console program. In that case, windows messages (like keyboard events) are processed by the console hosting your own program which then feeds your stdin and display what it gets from your stdout/stderr.

To be able to use a message loop, the common way is to first create a window. If you do not, you will only get messages explicitely sent to the thread from another program that would knows about it.

I'm sorry this is only hints, but a complete and detailed explaination would be far beyond a SO answer...