I'm trying to listen to events in a third-party app window, in which I don't own the source.

I don't understand this part of the

CodePudding user response：

The message loop needs to be in main, in your case after the call to SetWinEventHook. And since you don't otherwise have a way for your program to exit you'll probably want to create a dialog with an exit button, and in the handler for that buttons BN_CLICKED use a call to MessageBox to confirm that the user wants to exit and if so do a PostQuitMessage). The confirmation is because it would be too easy to exit otherwise.

CodePudding user response：

The message loop you have shown is perfectly fine (after moving it into EventHook()).

The "crash" is not really a crash. It is simply the program terminating itself abruptly because the thread is still running when the std::thread object is destroyed, as you have not called join() or detach() on it before it went out of scope when _tmain() exited.

Per std::thread::~thread:

Destroys the thread object.

If *this has an associated thread (joinable() == true), std::terminate() is called.

Notes

A thread object does not have an associated thread (and is safe to destroy) after

• it was default-constructed
• it was moved from
• join() has been called
• detach() has been called

So, simpy call t1.join() before _tmain() exits:

int _tmain(int argc, _TCHAR* argv[])
{
    std::thread t1(EventHook);
    ... 
    t1.join();
    return 0;
}