MultipleWindowThreads.c

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

enum {
	threadCnt = 3,
};

HINSTANCE gInst;
HANDLE gThreads[threadCnt];

LRESULT CALLBACK WndHandler(HWND wnd, UINT msg, WPARAM wp, LPARAM lp)
{
	switch (msg) {
	case WM_CREATE: {
		char str[256];
		sprintf(str, "Thread: %d", GetCurrentThreadId());
		SetWindowText(wnd, str);
		break;
	}
	case WM_DESTROY:
		PostQuitMessage(0);
		break;
	default:
		return DefWindowProc(wnd, msg, wp, lp);
	}
	return 0;
}

DWORD WINAPI ThreadEntry(void *arg)
{
	MSG msg;
	CreateWindow("Window", "Minimal Application", WS_VISIBLE | WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, 320, 240, NULL, NULL, gInst, NULL);
	while (GetMessage(&msg, NULL, 0, 0)) {
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}
	return 0;
}

int WINAPI WinMain(HINSTANCE inst, HINSTANCE prevInst, LPSTR cmdLine, int showCmd)
{
	gInst = inst;
	DWORD threadId;
	WNDCLASS wc = {0, WndHandler, 0, 0, inst, LoadIcon(NULL, IDI_APPLICATION), LoadCursor(NULL, IDC_ARROW), (HBRUSH)(COLOR_BTNFACE+1), 0, "Window"};
	RegisterClass(&wc);
	for (int i = 0; i < threadCnt; i++) {
		gThreads[i] = CreateThread(NULL, 0, ThreadEntry, NULL, 0, &threadId);
	}
	WaitForMultipleObjects(threadCnt, gThreads, TRUE, INFINITE);
	for (int i = 0; i < threadCnt; i++) {
		CloseHandle(gThreads[i]); gThreads[i] = 0;
	}
	return 0;
}